Honors & Awards

  • Understanding severe disruptive behaviors in adolescents with fragile X syndrome (R21), NICHD (2013-2015)
  • Evaluating an Intensive Behavioral Intervention for Children with Fragile X Syndrome (K08), NIMH (2008-2013)
  • Environmental, physiological and neural correlates of skin-picking in Prader-Willi syndrome, Foundation for Prader-Willi Research (2011-2012)

Boards, Advisory Committees, Professional Organizations

  • BCBA-D, Behavior Analyst Certification Board (2002 - Present)

Professional Education

  • PhD, Institute of Psychiatry, Psychology (1997)

Research & Scholarship

Current Research and Scholarly Interests

My primary area of interest is understanding the pathogenesis of problem behaviors shown by individuals diagnosed with neurogenetic disorders such as fragile X syndrome, Cornelia de Lange syndrome and Prader-Willi syndrome. I study methods for determining how environmental and biological factors can affect the development of aberrant behaviors in these syndromes. The end goal of my research is to create patient-specific methods for treating the symptoms of these disorders.


2013-14 Courses


Journal Articles

  • High rates of comorbid depressive and anxiety disorders among women with premutation of the FMR1 gene. American journal of medical genetics. Part B, Neuropsychiatric genetics : the official publication of the International Society of Psychiatric Genetics Kenna, H. A., Tartter, M., Hall, S. S., Lightbody, A. A., Nguyen, Q., de los Angeles, C. P., Reiss, A. L., Rasgon, N. L. 2013; 162 (8): 872-878


    Phenotypic variations are emerging from investigations of carriers of the fragile X mental retardation 1 (FMR1) premutation gene (55 to 200 CGG repeats). Initial studies suggest elevated psychiatric and reproductive system dysfunction, but have largely used self-reports for assessment of psychiatric history. The present study used diagnostic psychiatric interviews and assessed reproductive and menstrual history in women with FMR1 premutation. History of psychiatric diagnoses and data on reproductive functioning were collected in 46 women with FMR1 premutation who were mothers of at least one child with the fragile X full mutation. Results showed a significantly earlier age of menopause (mean age = 45.6 years) relative to the national average age of menopause (mean age = 51 years) and a high rate (76%) of lifetime depressive or anxiety history, with 43% of the overall sample reporting a comorbid history of both diagnoses. Compared to those free of psychiatric history, significantly longer premutation length was observed among women with psychiatric history after adjusting for age, with comorbid women having the highest number of CGG repeats (mean = 95.8) compared to women free of psychiatric history (mean = 79.9). Psychiatric history did not appear significantly related to reproductive system dysfunction, though results may have been obscured by the high rates of psychiatric dysfunction in the sample. These data add to the growing evidence base that women with the FMR1 premutation have an increased risk of psychiatric illness and risk for early menopause. Future investigations may benefit from inclusion of biochemical reproductive markers and longitudinal assessment of psychiatric and reproductive functioning. © 2013 Wiley Periodicals, Inc.

    View details for DOI 10.1002/ajmg.b.32196

    View details for PubMedID 24003006

  • Examining the Relationship Between Heart Rate and Problem Behavior: A Case Study of Severe Skin Picking in Prader-Willi Syndrome AJIDD-AMERICAN JOURNAL ON INTELLECTUAL AND DEVELOPMENTAL DISABILITIES Hall, S. S., Hammond, J. L., Hustyi, K. M. 2013; 118 (6): 460-474


    Abstract Few studies have examined the relationship between heart rate and self-injurious behavior (SIB) shown by individuals with IDD (intellectual and developmental disabilities). In this single-case study, we simultaneously monitored heart rate and activity levels during a functional analysis of severe skin picking behavior exhibited by a young man with Prader-Willi syndrome (PWS). Results of the functional analysis indicated that the participant's skin picking was maintained by automatic reinforcement. A within-session analysis of the data indicated that skin picking bouts resulted in an increase in heart rate, suggesting a positive- automatic reinforcement function. These data indicate that inclusion of heart rate and activity-level monitoring during a functional analysis may provide important additional information concerning the determinants of SIB.

    View details for DOI 10.1352/1944.7558-118.6.460

    View details for Web of Science ID 000330185500007

    View details for PubMedID 24432859

  • Identifying large-scale brain networks in fragile x syndrome. JAMA psychiatry Hall, S. S., Jiang, H., Reiss, A. L., Greicius, M. D. 2013; 70 (11): 1215-1223


    Fragile X syndrome (FXS) is an X-linked neurogenetic disorder characterized by a cognitive and behavioral phenotype resembling features of autism spectrum disorder. Until now, research has focused largely on identifying regional differences in brain structure and function between individuals with FXS and various control groups. Very little is known about the large-scale brain networks that may underlie the cognitive and behavioral symptoms of FXS.To identify large-scale, resting-state networks in FXS that differ from control individuals matched on age, IQ, and severity of behavioral and cognitive symptoms.Cross-sectional, in vivo neuroimaging study conducted in an academic medical center. Participants (aged 10-23 years) included 17 males and females with FXS and 16 males and females serving as controls.Univariate voxel-based morphometric analyses, fractional amplitude of low-frequency fluctuations (fALFF) analysis, and group-independent component analysis with dual regression.Patients with FXS showed decreased functional connectivity in the salience, precuneus, left executive control, language, and visuospatial networks compared with controls. Decreased fALFF in the bilateral insular, precuneus, and anterior cingulate cortices also was found in patients with FXS compared with control participants. Furthermore, fALFF in the left insular cortex was significantly positively correlated with IQ in patients with FXS. Decreased gray matter density, resting-state connectivity, and fALFF converged in the left insular cortex in patients with FXS.Fragile X syndrome results in widespread reductions in functional connectivity across multiple cognitive and affective brain networks. Converging structural and functional abnormalities in the left insular cortex, a region also implicated in individuals diagnosed with autism spectrum disorder, suggests that insula integrity and connectivity may be compromised in FXS. This method could prove useful in establishing an imaging biomarker for FXS.

    View details for DOI 10.1001/jamapsychiatry.2013.247

    View details for PubMedID 24068330

  • An analysis of the topography, severity, potential sources of reinforcement, and treatments utilized for skin picking in Prader-Willi syndrome RESEARCH IN DEVELOPMENTAL DISABILITIES Hustyi, K. M., Hammond, J. L., Rezvani, A. B., Hall, S. S. 2013; 34 (9): 2890-2899


    We examined the topography, severity, potential sources of reinforcement, and treatments utilized for skin-picking behavior shown by individuals with Prader-Willi syndrome (PWS). The parents of 55 individuals with PWS, aged 6-25 years, were interviewed about their child's skin-picking behavior using the Self-Injury Trauma Scale (SIT; Iwata, Pace, Kissel, Nau, & Farber, 1990) and the Functional Analysis Screening Tool (FAST; Iwata, DeLeon, & Roscoe, 2013). Results showed that skin picking in PWS occurred on the extremities (i.e., arms, legs, hands, and feet) for 75% of cases and resulted in bodily injury for 83.7% cases. Skin picking posed a high risk to the individual concerned in 41.8% of cases. Automatic sensory stimulation was identified as a potential source of reinforcement in the majority of cases (52.7%) followed by access to social attention or preferred items (36.4%). Treatments utilized by parents were primarily behavioral strategies (56.3%) followed by basic first aid (54.5%). There were no differences in the topography, severity or potential source of reinforcement between those with the deletion (DEL) subtype and those with the uniparental disomy (UPD) subtype. Taken together, these data indicate that skin picking shown by individuals with PWS is a particularly severe and intractable behavioral issue that may be maintained by (as yet unknown) sensory consequences. Further studies to identify the determinants of skin picking in PWS are therefore needed. The implications for interventions are discussed.

    View details for DOI 10.1016/j.ridd.2013.06.014

    View details for Web of Science ID 000322423200049

    View details for PubMedID 23810929

  • Delineating the Profile of Autism Spectrum Disorder Characteristics in Cornelia de Lange and Fragile X Syndromes AJIDD-AMERICAN JOURNAL ON INTELLECTUAL AND DEVELOPMENTAL DISABILITIES Moss, J., Oliver, C., Nelson, L., Richards, C., Hall, S. 2013; 118 (1): 55-73


    An atypical presentation of autism spectrum disorder is noted in Cornelia de Lange and Fragile X syndromes, but there are few detailed empirical descriptions. Participants in this study were individuals with Cornelia de Lange syndrome (n  =  130, M age  =  17.19), Fragile X syndrome (n  =  182, M age  =  16.94), and autism spectrum disorder (n  =  142, M age  =  15.19), who were comparable on chronological age. Using the Social Communication Questionnaire, the proportion meeting cutoff for autism spectrum disorder and autism was 78.6%, and 45.6%, respectively, in Cornelia de Lange syndrome and 83.6% and 48.6% in Fragile X syndrome. Domain and item analyses indicate differing, atypical autism spectrum disorder profiles in Fragile X and Cornelia de Lange syndromes. A limited association between adaptive behavior and autism spectrum disorder was identified in all groups. The findings have implications for intervention in genetic syndromes and conceptualization of autism spectrum disorder in the wider population.

    View details for DOI 10.1352/1944-7558-118.1.55

    View details for Web of Science ID 000317912500006

    View details for PubMedID 23301903

  • A 'learning platform' approach to outcome measurement in fragile X syndrome: a preliminary psychometric study JOURNAL OF INTELLECTUAL DISABILITY RESEARCH Hall, S. S., Hammond, J. L., Hirt, M., Reiss, A. L. 2012; 56 (10): 947-960


    Clinical trials of medications to alleviate the cognitive and behavioural symptoms of individuals with fragile X syndrome (FXS) are now underway. However, there are few reliable, valid and/or sensitive outcome measures available that can be directly administered to individuals with FXS. The majority of assessments employed in clinical trials may be suboptimal for individuals with intellectual disability (ID) because they require face-to-face interaction with an examiner, taxing administration periods, and do not provide reinforcement and/or feedback during the test. We therefore examined the psychometric properties of a new computerised 'learning platform' approach to outcome measurement in FXS.A brief computerised test, incorporated into the Discrete Trial Trainer©- a commercially available software program designed for children with ID - was administered to 13 girls with FXS, 12 boys with FXS and 15 matched ID controls aged 10 to 23 years (mental age = 4 to 12 years). The software delivered automated contingent access to reinforcement, feedback, token delivery and prompting procedures (if necessary) on each trial to facilitate responding. The primary outcome measure was the participant's learning rate, derived from the participant's cumulative record of correct responses.All participants were able to complete the test and floor effects appeared to be minimal. Learning rates averaged approximately five correct responses per minute, ranging from one to eight correct responses per minute in each group. Test-retest reliability of the learning rates was 0.77 for girls with FXS, 0.90 for boys with FXS and 0.90 for matched ID controls. Concurrent validity with raw scores obtained on the Arithmetic subtest of the Wechsler Intelligence Scale for Children-III was 0.35 for girls with FXS, 0.80 for boys with FXS and 0.56 for matched ID controls. The learning rates were also highly sensitive to change, with effect sizes of 1.21, 0.89 and 1.47 in each group respectively following 15 to 20, 15-min sessions of intensive discrete trial training conducted over 1.5 days.These results suggest that a learning platform approach to outcome measurement could provide investigators with a reliable, valid and highly sensitive measure to evaluate treatment efficacy, not only for individuals with FXS but also for individuals with other ID.

    View details for DOI 10.1111/j.1365-2788.2012.01560.x

    View details for Web of Science ID 000308872200003

    View details for PubMedID 22533667

  • Psychometric Study of the Aberrant Behavior Checklist in Fragile X Syndrome and Implications for Targeted Treatment JOURNAL OF AUTISM AND DEVELOPMENTAL DISORDERS Sansone, S. M., Widaman, K. F., Hall, S. S., Reiss, A. L., Lightbody, A., Kaufmann, W. E., Berry-Kravis, E., Lachiewicz, A., Brown, E. C., Hessl, D. 2012; 42 (7): 1377-1392


    Animal studies elucidating the neurobiology of fragile X syndrome (FXS) have led to multiple controlled trials in humans, with the Aberrant Behavior Checklist-Community (ABC-C) commonly adopted as a primary outcome measure. A multi-site collaboration examined the psychometric properties of the ABC-C in 630 individuals (ages 3-25) with FXS using exploratory and confirmatory factor analysis. Results support a six-factor structure, with one factor unchanged (Inappropriate Speech), four modified (Irritability, Hyperactivity, Lethargy/Withdrawal, and Stereotypy), and a new Social Avoidance factor. A comparison with ABC-C data from individuals with general intellectual disability and a list of commonly endorsed items are also reported. Reformulated ABC-C scores based on this FXS-specific factor structure may provide added outcome measure specificity and sensitivity in FXS clinical trials.

    View details for DOI 10.1007/s10803-011-1370-2

    View details for Web of Science ID 000305231000009

    View details for PubMedID 21972117

  • Effects of intranasal oxytocin on social anxiety in males with fragile X syndrome PSYCHONEUROENDOCRINOLOGY Hall, S. S., Lightbody, A. A., McCarthy, B. E., Parker, K. J., Reiss, A. L. 2012; 37 (4): 509-518


    Fragile X syndrome (FXS) is a rare inherited genetic disorder causing severe intellectual disability and autistic-like symptoms. Individuals with FXS, males in particular, often exhibit extreme eye gaze avoidance and hyperarousal when they encounter stressful social situations. We investigated whether oxytocin (OT), a hormone with prosocial and anxiolytic effects, could alleviate symptoms of social anxiety in this population. A randomized double-blind placebo-controlled single-dose trial was performed with intranasal administration of placebo, 24 IU OT and 48 IU OT. Measures of eye gaze frequency, heart rate, respiratory sinus arrhythmia (RSA), heart rate variability (HRV) and salivary cortisol were obtained during a structured social challenge conducted 50 min following OT administration. Ten low-functioning males with FXS (aged 13-28 years) traveled to Stanford for the initial visit: 8 completed the study. Eye gaze frequency improved significantly in response to the 24 IU OT dose and salivary cortisol levels decreased significantly in response to the 48 IU OT dose. There was no effect of OT on heart rate, RSA or HRV although individual plots of the heart rate data suggested that OT increased heart rate in some participants and decreased heart rate in others. These findings suggest that intranasal administration of OT may ameliorate some symptoms of social anxiety in patients with FXS. Further double-blind placebo-controlled studies of OT, conducted in combination with behavioral treatment programs, may be warranted.

    View details for DOI 10.1016/j.psyneuen.2011.07.020

    View details for Web of Science ID 000302044800007

    View details for PubMedID 21862226

  • Effects of computerized match-to-sample training on emergent fraction-decimal relations in individuals with fragile X syndrome RESEARCH IN DEVELOPMENTAL DISABILITIES Hammond, J. L., Hirt, M., Hall, S. S. 2012; 33 (1): 1-11


    Individuals diagnosed with fragile X syndrome (FXS), the most common known form of inherited intellectual disability, are reported to exhibit considerable deficits in mathematical skills that are often attributed to brain-based abnormalities associated with the syndrome. We examined whether participants with FXS would display emergent fraction-decimal relations following brief, intensive match-to-sample training on baseline relations. The performance profiles on tests of symmetry and transitivity/equivalence of 11 participants with FXS, aged 10-23 years, following baseline match-to-sample training were compared to those of 11 age- and IQ-matched controls with idiopathic developmental disability. The results showed that both groups of participants showed significant improvements in the baseline (trained) relations, as expected. However, participants with FXS failed to show significant improvements in the (untrained) symmetry and transitivity/equivalence relations compared to those in the control group. A categorical analysis of the data indicated that five participants with FXS and eight controls showed at least "intermediate" emergence of symmetry relations, whereas one individual with FXS and three controls showed at least intermediate emergence of transitivity/equivalence relations. A correlation analysis of the data indicated that improvements in the symmetry relations were significantly associated with improvements in the transitivity/equivalence relations in the control group (r=.69, p=.018), but this was not the case in the FXS group (r=.34, p>.05). Participant IQ was significantly associated with improvements in the symmetry relations in individuals with FXS (r=.60, p=.049), but not in controls (r=.21, p>.05). Taken together, these results suggest that brief, computerized match-to-sample training may produce emergent mathematical relations for a subset of children with FXS and developmental disabilities. However, the ability of individuals with FXS to form transitivity/equivalence relations may be impaired relative to those with idiopathic developmental disabilities, which may be attributed to neurodevelopmental variables associated with the syndrome.

    View details for DOI 10.1016/j.ridd.2011.08.021

    View details for Web of Science ID 000297661500001

    View details for PubMedID 22093642

  • Aberrant Frontal Lobe Maturation in Adolescents with Fragile X Syndrome is Related to Delayed Cognitive Maturation BIOLOGICAL PSYCHIATRY Bray, S., Hirt, M., Jo, B., Hall, S. S., Lightbody, A. A., Walter, E., Chen, K., Patnaik, S., Reiss, A. L. 2011; 70 (9): 852-858


    Fragile X syndrome (FXS) is the most common known heritable cause of intellectual disability. Prior studies in FXS have observed a plateau in cognitive and adaptive behavioral development in early adolescence, suggesting that brain development in FXS may diverge from typical development during this period.In this study, we examined adolescent brain development using structural magnetic resonance imaging data acquired from 59 individuals with FXS and 83 typically developing control subjects aged 9 to 22, a subset of whom were followed up longitudinally (1-5 years; typically developing: 17, FXS: 19). Regional volumes were modeled to obtain estimates of age-related change.We found that while structures such as the caudate showed consistent volume differences from control subjects across adolescence, prefrontal cortex (PFC) gyri showed significantly aberrant maturation. Furthermore, we found that PFC-related measures of cognitive functioning followed a similarly aberrant developmental trajectory in FXS.Our findings suggest that aberrant maturation of the PFC during adolescence may contribute to persistent or increasing intellectual deficits in FXS.

    View details for DOI 10.1016/j.biopsych.2011.05.038

    View details for Web of Science ID 000296228000012

    View details for PubMedID 21802660

  • Insular volume reduction in fragile X syndrome INTERNATIONAL JOURNAL OF DEVELOPMENTAL NEUROSCIENCE Cohen, J. D., Nichols, T., Brignone, L., Hall, S. S., Reiss, A. L. 2011; 29 (4): 489-494


    Fragile X syndrome (FraX) is the most common form of inherited mental deficit and is caused by mutations of the Fragile X Mental Retardation 1 (FMR1) gene on the X chromosome. While males and females with the full FMR1 mutation are affected differently because the disorder is X-linked, both suffer from varying degrees of cognitive impairment, attention deficits and social anxiety. The insula is a sensory integrative region that has been increasingly suggested as a critical area involved in anxiety manifestation. The current study was designed to examine possible changes in insular volume in FraX compared to age- and gender-matched typically developing healthy controls (HC) as well as age-, gender-, and intelligence-matched developmentally delayed controls (DD). An established native-space, manual morphometry method was utilized to quantify total and regional insular volumes using structural magnetic resonance imaging. Total, anterior and posterior insular volumes were found to be reduced in FraX compared to both HC and DD. The current data add to a growing literature concerning brain abnormalities in FraX and suggests that significant volume reduction of the insula is a component of the FraX neuroanatomical phenotype. This finding also provides an intriguing potential neural correlate for hyperarousal and gaze aversion, which are prominent behavioral symptoms of FraX.

    View details for DOI 10.1016/j.ijdevneu.2011.01.003

    View details for Web of Science ID 000291506000016

    View details for PubMedID 21291994

  • Behavioural Excesses and Deficits Associated with Dementia in Adults who have Down Syndrome JOURNAL OF APPLIED RESEARCH IN INTELLECTUAL DISABILITIES Oliver, C., Kalsy, S., McQuillan, S., Hall, S. 2011; 24 (3): 208-216
  • Functional analysis and treatment of aggressive behavior following resection of a craniopharyngioma DEVELOPMENTAL MEDICINE AND CHILD NEUROLOGY Hammond, J. L., Hall, S. S. 2011; 53 (4): 369-374


    Craniopharyngioma is a relatively rare, benign tumor that most often affects pre-adolescent children. Surgical resection is a common form of treatment, which may result in adverse physical, neurological, and behavioral effects, most notably, aggressive behavior. In this case study we describe a typically developing 6 year old female who had resection of a craniopharyngioma and subsequently developed severe aggressive behavior that interfered significantly with her recovery and functioning. Results of a functional analysis indicated that her aggression was maintained by contingent escape from task demands and access to preferred food items. A highly structured behavioral intervention, consisting of differential reinforcement of alternative behaviors, together with extinction targeted to each function of the behavior, was effective in reducing her aggression to below 88% of baseline levels. Her adaptive behaviors also increased significantly. These results suggest that assessment and treatment utilizing principles of applied behavior analysis can ameliorate the occurrence of problem behavior following craniopharyngioma resection.

    View details for DOI 10.1111/j.1469-8749.2010.03887.x

    View details for Web of Science ID 000288380600019

    View details for PubMedID 21232057

  • Autism in Fragile X Syndrome: A Category Mistake? JOURNAL OF THE AMERICAN ACADEMY OF CHILD AND ADOLESCENT PSYCHIATRY Hall, S. S., Lightbody, A. A., Hirt, M., Rezvani, A., Reiss, A. L. 2010; 49 (9): 921-933


    Many investigators now routinely classify children with fragile X syndrome (FXS) according to whether or not they also meet diagnostic criteria for autism. To determine whether this classification is appropriate, we examined the profiles of autistic behaviors shown by boys and girls with FXS.Individuals with FXS, aged 5 to 25 years, were assessed on two established measures of autism, the Social Communication Questionnaire (SCQ) and the Autism Diagnostic Observation Schedule (ADOS).We found that 35.1% of boys and 4.3% of girls with FXS scored in the "autism" category on both instruments. Analysis of the symptom profile indicated that both boys and girls with FXS showed lower rates of impairment on communication and reciprocal social interaction items than the reference autism samples on the measures. Furthermore, a regression model showed that IQ was significantly negatively associated with the SCQ total score in both boys and girls with FXS, when controlling for age, medication use, and FMRP levels.These data suggest that there are significant differences in the profile of social and communicative symptomatology in FXS compared with individuals diagnosed with idiopathic autism. Given these differences, the implementation of standard autism interventions for individuals with FXS may not be optimal. Maintaining the conceptual distinction between FXS (an established biological disease) and idiopathic autism (a phenomenologically defined behavioral disorder) may also facilitate the development of more targeted and thus effective interventions for individuals with FXS in the future.

    View details for DOI 10.1016/j.jaac.2010.07.001

    View details for Web of Science ID 000281331400006

    View details for PubMedID 20732628

  • Self-injurious behaviour in Cornelia de Lange syndrome: 2. association with environmental events JOURNAL OF INTELLECTUAL DISABILITY RESEARCH Sloneem, J., Arron, K., Hall, S. S., Oliver, C. 2009; 53: 590-603


    Self-injurious behaviour is commonly seen in Cornelia de Lange syndrome (CdLS). However, there has been limited research into the aetiology of self-injury in CdLS and whether environmental factors influence the behaviour.We observed the self-injury of 27 individuals with CdLS and 17 participants who did not have CdLS matched for age, gender, level of intellectual disability and mobility. Descriptive analyses were used to determine the extent to which environmental events were associated with self-injury.Lag sequential analysis of the association between self-injurious behaviour and environmental events revealed no differences between the two groups in terms of either the number or degree of environmental associations.The results suggest that the associations between the environment and self-injury in CdLS do not differ from those seen in the broader population of people with intellectual disability. By implication the social reinforcement hypothesis is equally applicable to both groups.

    View details for DOI 10.1111/j.1365-2788.2009.01183.x

    View details for Web of Science ID 000266923600002

    View details for PubMedID 19533839

  • Self-injurious behaviour in Cornelia de Lange syndrome: 1. Prevalence and phenomenology JOURNAL OF INTELLECTUAL DISABILITY RESEARCH Oliver, C., Sloneem, J., Hall, S., Arron, K. 2009; 53: 575-589


    Self-injurious behaviour is frequently identified as part of the behavioural phenotype of Cornelia de Lange syndrome (CdLS). We conducted a case-control study of the prevalence and phenomenology of self-injurious behaviour (SIB) in CdLS.A total of 54 participants with CdLS were compared with 46 individuals who were comparable on key variables including age, degree of intellectual disability and wheelchair use, using questionnaire and observational measures.Clinically significant self-injury was not more prevalent in the CdLS group (55.6%), nor was it different in presentation from that seen in the comparison group. Hyperactivity, stereotyped and compulsive behaviours predicted clinically significant self-injury in all participants. Hand directed, mild self-injury was more prevalent in CdLS.The results show that clinically significant self-injury may not be part of the behavioural phenotype of CdLS but a specific body target for proto-SIB is more common.

    View details for DOI 10.1111/j.1365-2788.2009.01179.x

    View details for Web of Science ID 000266923600001

    View details for PubMedID 19522788



    Aversion to eye contact is a common behavior of individuals diagnosed with Fragile X syndrome (FXS); however, no studies to date have attempted to increase eye-contact duration in these individuals. In this study, we employed a percentile reinforcement schedule with and without overcorrection to shape eye-contact duration of 6 boys with FXS. Results showed that although aversion to eye contact is often thought to be unamenable to change in FXS, it can be shaped in some individuals using percentile schedules either alone or in combination with overcorrection.

    View details for DOI 10.1901/jaba.2009.42-171

    View details for Web of Science ID 000263982700013

    View details for PubMedID 19721738

  • A solution to limitations of cognitive testing in children with intellectual disabilities: the case of fragile X syndrome JOURNAL OF NEURODEVELOPMENTAL DISORDERS Hessl, D., Nguyen, D. V., Green, C., Chavez, A., Tassone, F., Hagerman, R. J., Senturk, D., Schneider, A., Lightbody, A., Reiss, A. L., Hall, S. 2009; 1 (1): 33-45


    Intelligence testing in children with intellectual disabilities (ID) has significant limitations. The normative samples of widely used intelligence tests, such as the Wechsler Intelligence Scales, rarely include an adequate number of subjects with ID needed to provide sensitive measurement in the very low ability range, and they are highly subject to floor effects. The IQ measurement problems in these children prevent characterization of strengths and weaknesses, poorer estimates of cognitive abilities in research applications, and in clinical settings, limited utility for assessment, prognosis estimation, and planning intervention. Here, we examined the sensitivity of the Wechsler Intelligence Scale for Children (WISC-III) in a large sample of children with fragile X syndrome (FXS), the most common cause of inherited ID. The WISC-III was administered to 217 children with FXS (age 6-17 years, 83 girls and 134 boys). Using raw norms data obtained with permission from the Psychological Corporation, we calculated normalized scores representing each participant's actual deviation from the standardization sample using a z-score transformation. To validate this approach, we compared correlations between the new normalized scores versus the usual standard scores with a measure of adaptive behavior (Vineland Adaptive Behavior Scales) and with a genetic measure specific to FXS (FMR1 protein or FMRP). The distribution of WISC-III standard scores showed significant skewing with floor effects in a high proportion of participants, especially males (64.9%-94.0% across subtests). With the z-score normalization, the flooring problems were eliminated and scores were normally distributed. Furthermore, we found correlations between cognitive performance and adaptive behavior, and between cognition and FMRP that were very much improved when using these normalized scores in contrast to the usual standardized scores. The results of this study show that meaningful variation in intellectual ability in children with FXS, and probably other populations of children with neurodevelopmental disorders, is obscured by the usual translation of raw scores into standardized scores. A method of raw score transformation may improve the characterization of cognitive functioning in ID populations, especially for research applications.

    View details for DOI 10.1007/s11689-008-9001-8

    View details for Web of Science ID 000274727000004

    View details for PubMedID 19865612

  • The neural basis of auditory temporal discrimination in girls with fragile X syndrome JOURNAL OF NEURODEVELOPMENTAL DISORDERS Hall, S. S., Walter, E., Sherman, E., Hoeft, F., Reiss, A. L. 2009; 1 (1): 91-99


    Fragile X syndrome (FXS) is a common genetic disorder in which temporal processing may be impaired. To our knowledge however, no studies have examined the neural basis of temporal discrimination in individuals with FXS using functional magnetic resonance imaging (fMRI). Ten girls with fragile X syndrome and ten developmental age-matched typically developing controls performed an auditory temporal discrimination task in a 3T scanner. Girls with FXS showed significantly greater brain activation in a left-lateralized network, comprising left medial frontal gyrus, left superior and middle temporal gyrus, left cerebellum, and left brainstem (pons), when compared to a developmental age-matched typically developing group of subjects who had similar in-scanner task performance. There were no regions that showed significantly greater brain activation in the control group compared to individuals with FXS. These data indicate that networks of brain regions involved in auditory temporal processing may be dysfunctional in FXS. In particular, it is possible that girls with FXS employ left hemispheric resources to overcompensate for relative right hemispheric dysfunction.

    View details for DOI 10.1007/s11689-009-9007-x

    View details for Web of Science ID 000274727000008

    View details for PubMedID 19890439

  • Physiological Correlates of Social Avoidance Behavior in Children and Adolescents With Fragile X Syndrome JOURNAL OF THE AMERICAN ACADEMY OF CHILD AND ADOLESCENT PSYCHIATRY Hall, S. S., Lightbody, A. A., Huffman, L. C., Lazzeroni, L. C., Reiss, A. L. 2009; 48 (3): 320-329


    To investigate whether eye-gaze avoidance, a striking phenotypic feature in fragile X syndrome (FXS), is associated with high levels of "hyperarousal" during social interactions with others. To date, almost all studies in this area have been confounded by inclusion of task demands in addition to social demands.We monitored the cardiovascular activity and eye-gaze avoidance of 50 boys and girls with FXS aged 5 to 20 years during a 25-minute intensive social interaction session with an unfamiliar experimenter. To control for possible family and genetic factors in cardiovascular activity, we compared each child with FXS with their same-sex typically developing biological sibling.Participants with FXS obtained significantly higher heart rates, lower vagal tone, and lower heart rate variability estimates both at baseline and during the social interaction session compared with their typically developing siblings. Although eye-gaze avoidance occurred at significantly higher levels in the children with FXS, this behavior decreased slightly over the course of the session (a "warm-up" effect) and did not seem to be associated with cardiovascular activity. In the girls with FXS, higher levels of the fragile X mental retardation protein were associated with higher (and more typical) heart rate variability.These data suggest that both sympathetic and parasympathetic nervous systems are dysregulated in FXS. However, given that prolonged exposure to social demands does not inevitably lead to increased anxiety or "hyperarousal," professionals should not be deterred from providing much needed social skills interventions for individuals with FXS.

    View details for DOI 10.1097/CHI.0b013e318195bd15

    View details for Web of Science ID 000263742100011

    View details for PubMedID 19182690



    Research into the determinants and developmental course of fragile X syndrome (FXS) has made remarkable progress over the last 25 years. However, treatments to ameliorate the symptoms of FXS have been less forthcoming. While there is optimism in the field that the pace of intervention research is quickening, there has been a bias toward psychopharmacological approaches to treatment. A closer look at the data from those investigations reveals a paucity of evidence that medications can improve intellectual and adaptive functioning in FXS, or decrease associated behavioral and/or emotional issues. Work in other related disorders (e.g., autism) has shown that dramatic improvements in intellectual and adaptive functioning, as well as behavioral and emotional problems, can occur if intensive behavioral treatment is begun early in the child's life. It is hoped that future research efforts will evaluate these intensive early intervention strategies in children with FXS, perhaps in combination with pharmacological approaches.

    View details for DOI 10.1002/ddrr.78

    View details for Web of Science ID 000273207500011

    View details for PubMedID 20014373

  • Behavioural phenotype of Cornelia de Lange syndrome: case-control study BRITISH JOURNAL OF PSYCHIATRY Oliver, C., Arron, K., Sloneem, J., Hall, S. 2008; 193 (6): 466-470


    Cornelia de Lange syndrome is associated with abnormalities on chromosomes 5, 10 and X.To delineate the behavioural phenotype of Cornelia de Lange syndrome with specific reference to autistic-spectrum disorder.A total of 54 individuals with Cornelia de Lange syndrome (mean age 13.88 years; s.d.=8.58) and 46 comparable individuals with intellectual disability (mean age 13.74 years; s.d.=7.99) were assessed on measures of autistic-spectrum disorder, and adaptive, compulsive and disordered behaviour.There was no difference between the groups in global behaviour disorder. Severe autism was significantly more prevalent in the syndrome group (32.1%) than the comparison group (7.1%). In addition, the syndrome group also evidenced significantly higher levels of compulsive behaviour.These data suggest that autistic-spectrum disorder is part of the behavioural phenotype of Cornelia de Lange syndrome and that compulsive behaviours are evident. Future research should investigate this behavioural phenotype using contemporary diagnostic algorithms for autism with detailed examination of the phenomenology of compulsive behaviours.

    View details for DOI 10.1192/bjp.bp.107.044370

    View details for Web of Science ID 000261574600008

    View details for PubMedID 19043149

  • Aberrant Brain Activation During Gaze Processing in Boys With Fragile X Syndrome ARCHIVES OF GENERAL PSYCHIATRY Watson, C., Hoeft, F., Garrett, A. S., Hall, S. S., Reiss, A. L. 2008; 65 (11): 1315-1323


    Eye contact is a fundamental component of human social behavior. Individuals with fragile X syndrome (fraX), particularly male subjects, avoid eye contact and display other social deficits. To date (to our knowledge), this behavior in fraX has been studied only in female subjects, who show lesser degrees of gaze aversion.To determine the neural correlates of the perception of direct eye gaze in adolescent boys with fraX using functional magnetic resonance imaging.Cross-sectional study.Academic medical center.Thirteen adolescent boys with fraX, 10 boys with developmental delay, and 13 typically developing control subjects.Behavioral performance and brain activation during functional magnetic resonance imaging were evaluated during the presentation of faces with eye gaze directed to or averted away from subjects and during successive presentations of stimuli with eye gaze directed toward the subject. Whole-brain and region of interest analyses and regression analyses with task performance were performed.Significantly greater activation was observed in prefrontal cortices in controls compared with boys having fraX, who (in contrast) demonstrated elevated left insula activation to direct eye gaze stimuli. Furthermore, compared with controls, boys with fraX showed greater sensitization in the left amygdala with successive exposure to direct gaze.Compared with controls, boys with fraX display distinct patterns of brain activation in response to direct eye gaze. These results suggest that aberrant neural processing of direct eye gaze in subjects with fraX may be related to the associated avoidant response.

    View details for Web of Science ID 000260600300009

    View details for PubMedID 18981343

  • Longitudinal changes in intellectual development in children with Fragile X syndrome JOURNAL OF ABNORMAL CHILD PSYCHOLOGY Hall, S. S., Burns, D. D., Lightbody, A. A., Reiss, A. L. 2008; 36 (6): 927-939


    Structural equation modeling (SEM) was used to examine the development of intellectual functioning in 145 school-age pairs of siblings. Each pair included one child with Fragile X syndrome (FXS) and one unaffected sibling. All pairs of children were evaluated on the Wechsler Intelligence Scale for Children-Third Edition (WISC-III) at time 1 and 80 pairs of children received a second evaluation at time 2 approximately 4 years later. Compared to their unaffected siblings, children with FXS obtained significantly lower percentage correct scores on all subtests of the WISC at both time points. During the time between the first and second assessments, the annual rate of intellectual development was approximately 2.2 times faster in the unaffected children compared to the children with FXS. Levels of the fragile X mental retardation protein (FMRP) were highly associated with intellectual ability scores of the children with FXS at both time points (r=0.55 and 0.64 respectively). However, when gender, age, and the time between assessments were included as covariates in the structural equation model, FMRP accounted for only 5% of the variance in intellectual ability scores at time 1 and 13% of the variance at time 2. The results of this study suggest that slower learning contributes to the low and declining standardized IQ scores observed in children with FXS.

    View details for DOI 10.1007/s10802-008-9223-y

    View details for Web of Science ID 000257726600010

    View details for PubMedID 18347972

  • Health and sleep problems in Cornelia de Lange Syndrome: a case control study JOURNAL OF INTELLECTUAL DISABILITY RESEARCH Hall, S. S., Arron, K., Sloneem, J., Oliver, C. 2008; 52: 458-468


    Self-injury, sleep problems and health problems are commonly reported in Cornelia de Lange Syndrome (CdLS) but there are no comparisons with appropriately matched participants. The relationship between these areas and comparison to a control group is warranted.54 individuals with CdLS were compared with 46 participants with intellectual disability (ID) of mixed aetiology who were similar in terms of degree of ID, mobility, age and gender using informant-based measures of health problems, sleep and self-injury.Participants with CdLS experienced significantly more current and lifetime health problems with eye problems and gastrointestinal disorders prominent. Although 55% of those with CdLS experienced sleep problems this prevalence was not different from the comparison group. Sleep disorder was not associated with self-injury in the CdLS group, skin problems were associated with severity of self-injury but not presence.People with CdLS experience a range of significant health problems and have more health concerns than others with the same degree of ID. Although this has been well documented in the past, the current high prevalence of health concerns indicates the need for regular health assessment and appropriate intervention.

    View details for DOI 10.1111/j.1365-2788.2008.01047.x

    View details for Web of Science ID 000254990800009

    View details for PubMedID 18341525

  • Compulsive, self-injurious, and autistic behavior in children and adolescents with fragile X syndrome AMERICAN JOURNAL ON MENTAL RETARDATION Hall, S. S., Lightbody, A. A., Reiss, A. L. 2008; 113 (1): 44-53


    Compulsive, self-injurious, and autistic behaviors were examined in 31 boys and 29 girls with fragile X syndrome aged 5 to 20 years. Self-injurious behavior occurred in 58% of boys and 17% of girls, whereas compulsive behavior occurred in 72% of boys and 55% of girls and did not appear to be associated with self-injurious behavior. Fifty percent of boys and 20% of girls met diagnostic criteria for autism on the ADOS-G. Girls who showed compulsive behavior had lower levels of FMRP than girls who did not show compulsive behavior, and boys with autistic symptoms had lowered levels of cortisol. Taken together, these data suggest that autistic and compulsive behaviors are highly prevalent in fragile X syndrome and that lowered levels of FMRP and cortisol may be biological markers for these behaviors.

    View details for Web of Science ID 000252702800004

    View details for PubMedID 18173299

  • Neuroanatomy of fragile X syndrome is associated with aberrant behavior and the fragile X mental retardation protein (FMRP) ANNALS OF NEUROLOGY Gothelf, D., Furfaro, J. A., Hoeft, F., Eckert, M. A., Hall, S. S., O'Hara, R., Erba, H. W., Ringel, J., Hayashi, K. M., Patnaik, S., Golianu, B., Kraemer, H. C., Thompson, P. M., Piven, J., Reiss, A. L. 2008; 63 (1): 40-51


    To determine how neuroanatomic variation in children and adolescents with fragile X syndrome is linked to reduced levels of the fragile X mental retardation-1 protein and to aberrant cognition and behavior.This study included 84 children and adolescents with the fragile X full mutation and 72 typically developing control subjects matched for age and sex. Brain morphology was assessed with volumetric, voxel-based, and surface-based modeling approaches. Intelligence quotient was evaluated with standard cognitive testing, whereas abnormal behaviors were measured with the Autism Behavior Checklist and the Aberrant Behavior Checklist.Significantly increased size of the caudate nucleus and decreased size of the posterior cerebellar vermis, amygdala, and superior temporal gyrus were present in the fragile X group. Subjects with fragile X also demonstrated an abnormal profile of cortical lobe volumes. A receiver operating characteristic analysis identified the combination of a large caudate with small posterior cerebellar vermis, amygdala, and superior temporal gyrus as distinguishing children with fragile X from control subjects with a high level of sensitivity and specificity. Large caudate and small posterior cerebellar vermis were associated with lower fragile X mental retardation protein levels and more pronounced cognitive deficits and aberrant behaviors.Abnormal development of specific brain regions characterizes a neuroanatomic phenotype associated with fragile X syndrome and may mediate the effects of FMR1 gene mutations on the cognitive and behavioral features of the disorder. Fragile X syndrome provides a model for elucidating critical linkages among gene, brain, and cognition in children with serious neurodevelopmental disorders.

    View details for DOI 10.1002/ana.21243

    View details for Web of Science ID 000253008700007

    View details for PubMedID 17932962

  • Fragile X syndrome: Assessment and treatment implications CHILD AND ADOLESCENT PSYCHIATRIC CLINICS OF NORTH AMERICA Reiss, A. L., Hall, S. S. 2007; 16 (3): 663-?


    Fragile X syndrome (FraX) is the most common known cause of inherited mental impairment. FMR1 gene mutations, the cause of FraX, lead to reduced expression of FMR1 protein and an increased risk for a particular profile of cognitive, behavioral, and emotional dysfunction. The study of individuals with FraX provides a unique window of understanding into important disorders such as autism, social phobia, cognitive disability, and depression. This review highlights the typical phenotypic features of individuals with FraX, discussing the apparent strengths and weaknesses in intellectual functioning, as evidenced from longitudinal follow-up studies. It also discusses recent neuroanatomic findings that may pave the way for more focused disease-specific pharmacologic and behavioral interventions. This article describes the results of recent medication trials designed to target symptoms associated with FraX. It also describes some recent behavioral interventions that were conducted in our laboratory.

    View details for DOI 10.1016/j.chc.2007.03.001

    View details for Web of Science ID 000247944400010

    View details for PubMedID 17562585

  • Fronto-striatal dysfunction and potential compensatory mechanisms in male adolescents with fragile X syndrome HUMAN BRAIN MAPPING Hoeft, F., Hernandez, A., Parthasarathy, S., Watson, C. L., Hall, S. S., Reiss, A. L. 2007; 28 (6): 543-554


    Response inhibition is an important facet of executive function. Fragile X syndrome (FraX), with a known genetic etiology (fragile X mental retardation-1 (FMR1) mutation) and deficits in response inhibition, may be an ideal condition for elucidating interactions among gene-brain-behavior relationships. Functional magnetic resonance imaging (fMRI) studies have shown evidence of aberrant neural activity when individuals with FraX perform executive function tasks, though the specific nature of this altered activity or possible compensatory processes has yet to be elucidated. To address this question, we examined brain activation patterns using fMRI during a go/nogo task in adolescent males with FraX and in controls. The critical comparison was made between FraX individuals and age, gender, and intelligent quotient (IQ)-matched developmentally delayed controls; in addition to a control group of age and gender-matched typically developing individuals. The FraX group showed reduced activation in the right ventrolateral prefrontal cortex (VLPFC) and right caudate head, and increased contralateral (left) VLPFC activation compared with both control groups. Individuals with FraX, but not controls, showed a significant positive correlation between task performance and activation in the left VLPFC. This potential compensatory activation was predicted by the interaction between FMR1 protein (FMRP) levels and right striatal dysfunction. These results suggest that right fronto-striatal dysfunction is likely an identifiable neuro-phenotypic feature of FraX and that activation of the left VLPFC during successful response inhibition may reflect compensatory processes. We further show that these putative compensatory processes can be predicted by a complex interaction between genetic risk and neural function.

    View details for DOI 10.1002/hbm.20406

    View details for Web of Science ID 000246628900009

    View details for PubMedID 17437282

  • 3D pattern of brain abnormalities in Fragile X syndrome visualized using tensor-based morphometry NEUROIMAGE Lee, A. D., Leow, A. D., Lu, A., Reiss, A. L., Hall, S., Chiang, M., Toga, A. W., Thompson, P. M. 2007; 34 (3): 924-938


    Fragile X syndrome (FraX), a genetic neurodevelopmental disorder, results in impaired cognition with particular deficits in executive function and visuo-spatial skills. Here we report the first detailed 3D maps of the effects of the Fragile X mutation on brain structure, using tensor-based morphometry. TBM visualizes structural brain deficits automatically, without time-consuming specification of regions-of-interest. We compared 36 subjects with FraX (age: 14.66+/-1.58 S.D., 18 females/18 males), and 33 age-matched healthy controls (age: 14.67+/-2.2 S.D., 17 females/16 males), using high-dimensional elastic image registration. All 69 subjects' 3D T1-weighted brain MRIs were spatially deformed to match a high-resolution single-subject average MRI scan in ICBM space, whose geometry was optimized to produce a minimal deformation target. Maps of the local Jacobian determinant (expansion factor) were computed from the deformation fields. Statistical maps showed increased caudate (10% higher; p = 0.001) and lateral ventricle volumes (19% higher; p = 0.003), and trend-level parietal and temporal white matter excesses (10% higher locally; p = 0.04). In affected females, volume abnormalities correlated with reduction in systemically measured levels of the Fragile X mental retardation protein (FMRP; Spearman's r < -0.5 locally). Decreased FMRP correlated with ventricular expansion (p = 0.042; permutation test), and anterior cingulate tissue reductions (p = 0.0026; permutation test) supporting theories that FMRP is required for normal dendritic pruning in fronto-striatal-limbic pathways. No sex differences were found; findings were confirmed using traditional volumetric measures in regions of interest. Deficit patterns were replicated by performing statistics after logarithmic transformation, which may be more appropriate for tensor-valued data. Investigation of how these anomalies emerge over time will accelerate our understanding of FraX and its treatment.

    View details for DOI 10.1016/j.neuroimage.2006.09.043

    View details for Web of Science ID 000243758700007

    View details for PubMedID 17161622

  • Modeling family dynamics in children with fragile X syndrome JOURNAL OF ABNORMAL CHILD PSYCHOLOGY Hall, S. S., Burns, D. D., Reiss, A. L. 2007; 35 (1): 29-42


    Few studies have examined the impact of children with genetic disorders and their unaffected siblings on family functioning. In this study, the reciprocal causal links between problem behaviors and maternal distress were investigated in 150 families containing a child with fragile X syndrome (FXS) and an unaffected sibling. Both children's behavior problems appeared to have strong, direct effects on maternal distress, but maternal distress did not appear to have any reciprocal causal effects on either child's behavior problems. Surprisingly, there were no significant differences in the effects of the two children's behavior problems on maternal distress. These data suggest that the problem behaviors of children with FXS, as well as their unaffected siblings, can have a substantial and additive impact on maternal depression and anxiety. Future research efforts should employ longitudinal research designs to confirm these findings.

    View details for DOI 10.1007/s10802-006-9081-4

    View details for Web of Science ID 000244835500003

    View details for PubMedID 17165142

  • Social escape behaviors in children with fragile X syndrome JOURNAL OF AUTISM AND DEVELOPMENTAL DISORDERS Hall, S., DeBernardis, M., Reiss, A. 2006; 36 (7): 935-947


    Social escape behavior is a common behavioral feature of individuals with fragile X syndrome (fraX). In this observational study, we examined the effect of antecedent social and performance demands on problem behaviors in four conditions: face-to-face interview, silent reading, oral reading and a singing task. Results showed that problem behaviors were significantly more likely to occur during the interview and singing conditions. Higher levels of salivary cortisol were predictive of higher levels of fidgeting behavior and lower levels of eye contact in male participants. There were no associations between level of FMRP expression and social escape behaviors. These data suggest that specific antecedent biological and environmental factors evoke social escape behaviors in fragile X syndrome.

    View details for DOI 10.1007/s10803-006-0132-z

    View details for Web of Science ID 000241171600011

    View details for PubMedID 16897394

  • The acquisition of stimulus equivalence in individuals with fragile X syndrome JOURNAL OF INTELLECTUAL DISABILITY RESEARCH Hall, S. S., DeBernardis, G. M., Reiss, A. L. 2006; 50: 643-651


    Few studies have employed stimulus equivalence procedures to teach individuals with intellectual disabilities (IDs) new skills. To date, no studies of stimulus equivalence have been conducted in individuals with fragile X syndrome (FXS), the most common known cause of inherited ID.Five adolescents with FXS were taught basic math and geography skills by using a computerized stimulus equivalence training programme administered over 2 days in 2-h sessions.Four of the five participants learned the math relations, with one participant demonstrating stimulus equivalence at post-test. Three of the five participants learned the geography relations, with all three of these participants demonstrating stimulus equivalence at post-test.These data indicate that computerized stimulus equivalence procedures, conducted in time-limited sessions, may help individuals with FXS learn new skills. Hypotheses concerning the failure of some participants to learn the training relations and to demonstrate stimulus equivalence at post-test are discussed.

    View details for DOI 10.1111/j.1365-2788.2006.00814.x

    View details for Web of Science ID 000239258100003

    View details for PubMedID 16901291

  • Chronological age, but not FMRP levels, predicts neuropsychological performance in girls with fragile X syndrome AMERICAN JOURNAL OF MEDICAL GENETICS PART B-NEUROPSYCHIATRIC GENETICS Lightbody, A. A., Hall, S. S., Reiss, A. L. 2006; 141B (5): 468-472


    The effect of FMRP levels and chronological age on executive functioning, visual-spatial abilities ,and verbal fluency tasks were examined in 46 school-age girls with fragile X syndrome (FXS). Results indicated that FMRP levels were not predictive of outcome on the neuropsychological tests but that performance on the executive functioning task tended to worsen with chronological age. This age effect was not observed on the tests of visual-spatial abilities or verbal fluency. These data indicate that relative deficits in executive functioning in girls with FXS become more pronounced with age. In contrast, the relative deficits in spatial and verbal abilities of these girls did not appear to increase with age, suggesting that these abilities may be spared.

    View details for DOI 10.1002/ajmg.b.30307

    View details for Web of Science ID 000238622300006

    View details for PubMedID 16741913

  • Effects of social context on social interaction and self-injurious behavior in Cornelia de Lange syndrome AMERICAN JOURNAL ON MENTAL RETARDATION Oliver, C., Arron, K., Hall, S., Sloneem, J., Forman, D., McClintock, K. 2006; 111 (3): 184-192


    Cornelia de Lange syndrome is reported to be associated with self-injurious behavior (SIB) and social avoidance. We used analog methodology to examine the effect of manipulating adult social contact on social communicative behaviors and SIB in 16 children with this syndrome. For 9 participants engagement behavior was related to levels of adult attention, and SIB showed significant variability across conditions for 3 participants. These findings indicate that SIB can be affected by environmental factors, even though it is thought to be part of the behavioral phenotype of Cornelia de Lange syndrome and suggest that individuals with this syndrome show socially motivated attention-soliciting behaviors. The implications for gene-environment interactions are discussed.

    View details for Web of Science ID 000237836200003

    View details for PubMedID 16597185

  • Comparing descriptive, experimental and informant-based assessments of problem behaviors RESEARCH IN DEVELOPMENTAL DISABILITIES Hall, S. S. 2005; 26 (6): 514-526


    In this study, the outcomes of descriptive, experimental and informant-based methods of functional assessment were compared in four individuals with developmental disabilities who showed problem behaviors. Results indicated that the descriptive and experimental assessments were concordant in only one of the four cases whilst informant-based and experimental assessments were concordant in three of the four cases. The descriptive assessment identified thin schedules of attention in all cases. These results appear to question the usefulness of employing descriptive assessments for problem behaviors either as an adjunct or replacement for experimental assessments, particularly given their time-consuming nature.

    View details for DOI 10.1016/j.ridd.2004.11.004

    View details for Web of Science ID 000234062600002

    View details for PubMedID 16303582

  • Effects of increasing task load on memory impairment in adults with Down syndrome AMERICAN JOURNAL ON MENTAL RETARDATION Oliver, C., Holland, T., Hall, S., Crayton, L. 2005; 110 (5): 339-345


    The effect of increasing the number of stimuli to be recalled was investigated to evaluate whether sensitivity for memory impairment was enhanced in adults with Down syndrome when using higher task load. Three levels of load were compared across three groups of adults: those with cognitive deterioration, no cognitive deterioration over age 40, and no cognitive-deterioration under 40. The cognitive-deterioration group showed impaired performance in comparison to the no cognitive-deterioration-40+ group at all levels of task load, with performance declining over 4 years. The no cognitive-deterioration-40+ group showed no impairment in performance compared to no cognitive-deterioration-under 40 group, except when task load was high. Implications for identification of dementia and age-related cognitive change are discussed.

    View details for Web of Science ID 000231766200002

    View details for PubMedID 16080772

  • The early development of self-injurious behaviour: evaluating the role of social reinforcement JOURNAL OF INTELLECTUAL DISABILITY RESEARCH Oliver, C., Hall, S., Murphy, G. 2005; 49: 591-599


    The potential role of social reinforcement in the development of self-injury has not yet been subjected to empirical analysis. In this 2-year prospective study, the pattern of social interactions related to the early presentation of self-injury were examined to identify a potential association with an increase in self-injury.The self-injurious behaviour and social contact with adults of 16 children with intellectual disability (ID) with self-injury of recent onset were observed at 3-month intervals over 2 years.Increase in self-injury over a 2-year period was positively correlated with a distribution of social contact relative to episodes of self-injury that is consistent with a mutual social reinforcement paradigm. When this paradigm was operative, self-injury was evoked under stable antecedent conditions over time but tended to evoke increasing levels of social interaction.These results support the hypothesis that increases in the frequency of early self-injury in children with ID may be determined by social reinforcement with implications for early intervention and proactive identification of children at risk for increases in self-injury.

    View details for DOI 10.1111/j.1365-2788.2005.00694.x

    View details for Web of Science ID 000230290100002

    View details for PubMedID 16011552

  • The association between environmental events and self-injurious behaviour in Cornelia de Lange syndrome JOURNAL OF INTELLECTUAL DISABILITY RESEARCH Moss, J., Oliver, C., Hall, S., Arron, K., Sloneem, J., Petty, J. 2005; 49: 269-277


    There has been limited empirical research into the environmental causes of self-injury in Cornelia de Lange syndrome. The present study examined the variability of self-injurious behaviour in Cornelia de Lange syndrome across environmental setting events. Additionally, the association between setting events and more specific environmental events was examined.A descriptive analysis of observational data on eight children with Cornelia de Lange syndrome aged between 4 and 14 years was carried out. The association between self-injurious behaviour and four environmental setting events and between specific environmental events and setting events was examined using established statistical methods for observational data.Seven out of eight of the participants showed at least one form of self-injurious behaviour that was associated with a particular setting event. The study also demonstrated that the relationship between setting events and environmental events is extremely variable across individuals.Self-injurious behaviour in some individuals with Cornelia de Lange syndrome is associated with environmental events although the precise nature of the association warrants clarification. Using broad setting events as a methodological tool in isolation provides some insight into the role of specific environmental factors in maintaining self-injurious behaviour but the integrity of setting events must be established.

    View details for Web of Science ID 000227721500006

    View details for PubMedID 15816814

  • Structural and environmental characteristics of stereotyped behaviors AMERICAN JOURNAL ON MENTAL RETARDATION Hall, S., Thorns, T., Oliver, C. 2003; 108 (6): 391-402


    Structural and environmental characteristics of multiple topographies of stereotypic behaviors shown by 8 individuals with developmental disabilities are described. Analysis of structural characteristics show that the parameters of stereotyped behavior (percentage of time, bout length, and bout length variability) were highly correlated. Analysis of the influence of environmental variables indicated that topographies of stereotyped behaviors were more likely to occur under conditions of low stimulation and less likely during conditions involving social contact. Individuals whose stereotyped behaviors were less influenced by environmental factors were more likely to engage in them for greater periods of time. Results suggest that an examination of individual topographies of stereotyped behaviors and their structural and environmental characteristics may provide useful insights for understanding the origins of these behaviors.

    View details for Web of Science ID 000186297000003

    View details for PubMedID 14561109

  • Descriptive functional analysis of behavioral excesses shown by adults with Down syndrome and dementia INTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY Millichap, D., Oliver, C., McQuillan, S., Kalsy, S., Lloyd, V., Hall, S. 2003; 18 (9): 844-854


    The study examined the hypothesis that a functional relationship exists between social environmental events and behavioral excesses in individuals with Down syndrome and dementia.A case-series design was employed (n = 4) using an direct observation-based descriptive functional assessment procedure.Observations were conducted in the natural environments of four participants over periods ranging from 11 to 15.4 hours. Data were collected on non-verbal and verbal behavioral excesses, appropriate engagement and verbal interaction with others. Social environmental events observed including both staff and peer behavior.Analysis of co-occurrence for behavioral excesses and social environmental events indicated significant relationships for some behaviours consistent with operant reinforcement processes. Sequential analysis showed that changes in the probability of social contact occurred in the period directly preceding and following verbal behaviors.Results support the hypothesis that, consistent with literature for older adults with dementia in the general population, some behavioral excesses were functional in nature and not randomly occurring events. No relationship was found between appropriate engagement and staff contact. Evidence of the functional nature of target behavioral excesses indicates that behavioral interventions have potential for this client group.

    View details for DOI 10.1002/gps.930

    View details for Web of Science ID 000185363100011

    View details for PubMedID 12949853

  • Risk markers associated with challenging behaviours in people with intellectual disabilities: a meta-analytic study JOURNAL OF INTELLECTUAL DISABILITY RESEARCH McClintock, K., Hall, S., Oliver, C. 2003; 47: 405-416


    A meta-analysis of prevalence and cohort studies conducted over the last 30 years was carried out to identify risk markers for challenging behaviour shown by individuals with intellectual disabilities (IDs). A total of 86 potential studies was identified from the review, with 22 (25.6%) containing sufficient data to enable a statistical analysis to be conducted. Results indicated that males were significantly more likely to show aggression than females, and that individuals with a severe/profound degree of ID were significantly more likely to show self-injury and stereotypy than individuals with a mild/moderate degree of ID. Individuals with a diagnosis of autism were significantly more likely to show self-injury, aggression and disruption to the environment whilst individuals with deficits in receptive and expressive communication were significantly more likely to show self-injury. In most cases, tests for heterogeneity were statistically significant, as expected. The meta-analysis highlighted the paucity of methodologically robust studies of risk markers for challenging behaviours and the lack of data on incidence, prevalence and chronicity of challenging behaviour in this population.

    View details for Web of Science ID 000185203500001

    View details for PubMedID 12919191

  • Assessing the severity of challenging behaviour: Psychometric properties of the challenging behaviour interview JOURNAL OF APPLIED RESEARCH IN INTELLECTUAL DISABILITIES Oliver, C., McClintock, K., Hall, S., Smith, M., Dagnan, D., Stenfert-Kroese, B. 2003; 16 (1): 53-61
  • Phenomenology of self-restraint AMERICAN JOURNAL ON MENTAL RETARDATION Oliver, C., Murphy, G., Hall, S., Arron, K., Leggett, J. 2003; 108 (2): 71-81


    Self-restraint is often reported in individuals with mental retardation who show self-injurious behavior (SIB). In this study, the phenomenology and prevalence of self-restraint in individuals showing self-injury and wearing protective devices and those showing self-injury but not wearing protective devices were compared. A high prevalence of self-restraint in the whole sample of individuals showing self-injury was identified (67/88, 76.1%), and self-restraint was more prevalent in a group showing self-injury but not wearing protective devices (43/47, 91.5%) than in a group showing self-injury and wearing protective devices (24/41, 58.5%). Individuals not wearing protective devices showed a greater number of topographies of self-restraint than those who did wear them. Results are discussed with reference to the purely topographical definition of self-restraint employed and the potential equivalence of protective devices and self-restraint.

    View details for Web of Science ID 000181562900001

    View details for PubMedID 12564940

  • Transitions between cooperative and non-cooperative responding in the 'Pigeon's Dilemma' Behavioural processes Hall, S. S. 2003; 60 (3): 199-208


    Two pigeons played Iterated Prisoner's Dilemma (IPD) against a simulated opponent pre-programmed to play 'Tit-For-Tat' (TFT) and 'Random' (RND) strategies. Each pigeon received differential amounts of access to food following choices of either 'cooperate' or 'defect' on a trial. After 1000 trials against TFT and 500 trials against RND, results indicated that choice allocation was optimal when the birds played against RND but was sub-optimal when the birds played against TFT. In order to determine why the pigeons responded suboptimally against TFT, a trial-by-trial analysis of the data was conducted. The analysis revealed that once a pigeon had received the 'Sucker's' payoff (S), it was more likely to defect and receive the 'Temptation' payoff (T) than to cooperate and receive the 'Reward' (R) payoff. Local reinforcement contingencies appear to determine suboptimal responding against TFT in the iterated Pigeon's Dilemma.

    View details for PubMedID 12505173

  • Molecular analyses of the principal components of response strength JOURNAL OF THE EXPERIMENTAL ANALYSIS OF BEHAVIOR Killeen, P. R., Hall, S. S., Reilly, M. P., Kettle, L. C. 2002; 78 (2): 127-160


    Killeen and Hall (2001) showed that a common factor called strength underlies the key dependent variables of response probability, latency, and rate, and that overall response rate is a good predictor of strength. In a search for the mechanisms that underlie those correlations, this article shows that (a) the probability of responding on a trial is a two-state Markov process; (b) latency and rate of responding can be described in terms of the probability and period of stochastic machines called clocked Bernoulli modules, and (c) one such machine, the refractory Poisson process, provides a functional relation between the probability of observing a response during any epoch and the rate of responding. This relation is one of proportionality at low rates and curvilinearity at higher rates.

    View details for Web of Science ID 000177850900001

    View details for PubMedID 12216975

  • Effects of environmental events on smiling and laughing behavior in Angelman syndrome AMERICAN JOURNAL ON MENTAL RETARDATION Oliver, C., Demetriades, L., Hall, S. 2002; 107 (3): 194-200


    Angelman syndrome is a neurogenetic disorder associated with unique behaviors and characteristics, including an unusually happy expression, inability to speak, ataxia, mental retardation, and abnormal EEG. Previous research has suggested that smiling and laughing behaviors in Angelman syndrome are inappropriate, excessive, and dissociated from contextual events. In the present study, the variability of smiling and laughing behaviors of 3 individuals with Angelman syndrome was examined across typical social contexts. Results indicate that laughing and smiling increased during social situations and occurred at low levels during non-social situations. The behaviors, therefore, did not occur totally inappropriately, as has been suggested. The findings illustrate the need to divert attention to the examination of environmental influences on purported phenotypic behavior in genetic syndromes.

    View details for Web of Science ID 000175518200004

    View details for PubMedID 11966332

  • Self-injurious behavior, self-restraint, and compulsive Behaviors in Cornelia de Lange syndrome AMERICAN JOURNAL ON MENTAL RETARDATION Hyman, P., Oliver, C., Hall, S. 2002; 107 (2): 146-154


    Researchers have argued that individuals who show self-restraint are more likely to show self-injurious behavior (SIB) that is compulsive. Self-injurious behavior, self-restraint, and compulsive behaviors have been described as features of Cornelia de Lange syndrome. We examined whether individuals with this syndrome displaying SIB and self-restraint exhibit more compulsive behaviors than do those without SIB and self-restraint. Main caregivers of individuals with the syndrome completed questionnaires. A significant association was found between SIB and self-restraint, and those displaying both behaviors displayed significantly more compulsions than did those not exhibiting them. Findings extend the compulsive behavior theory and highlight areas for further research.

    View details for Web of Science ID 000174135100008

    View details for PubMedID 11853532

  • Descriptive analysis of self-injurious behaviour and self-restraint JOURNAL OF APPLIED RESEARCH IN INTELLECTUAL DISABILITIES Forman, D., Hall, S., Oliver, C. 2002; 15 (1): 1-7
  • Self-injurious behaviour in young children with Lesch-Nyhan syndrome DEVELOPMENTAL MEDICINE AND CHILD NEUROLOGY Hall, S., Oliver, C., Murphy, G. 2001; 43 (11): 745-749


    The early development of self-injurious behaviour in three young boys (aged 17, 25, and 30 months at start of study) with Lesch-Nyhan syndrome was examined by means of parental interviews and by direct observations completed at 3 to 4 monthly intervals over an 18-month period. Results suggest that the self-injury began in a different way from that of other young children with autism and/or developmental disabilities in that, from the start, self-injurious responses were sudden and violent, rather than emerging gradually over time. Drastic measures, such as removal of the teeth or provision of tooth guards, were often taken to prevent further tissue damage. Direct observations showed that the boys' self-injury occurred at lower rates, but their carers were highly concerned about the behaviour. Sequential analysis of the observational data indicated that on some occasions the children were more likely to self-injure during periods of low social interaction, suggesting that their self-injury may have been influenced by environmental factors. The theoretical and practical implications of these findings are discussed.

    View details for Web of Science ID 000172366500005

    View details for PubMedID 11730148

  • Effects of social proximity on multiple aggressive behaviors JOURNAL OF APPLIED BEHAVIOR ANALYSIS Oliver, C., Oxener, G., Hearn, M., Hall, S. 2001; 34 (1): 85-88


    We systematically manipulated social proximity to examine its influence on multiple topographies of aggression. Aggression occurred at high levels during close-proximity sessions and at low levels during distant-proximity sessions even though social contact was presented continuously during both conditions. Topographies of aggression emerged sequentially across the close-proximity sessions, and all topographies were reduced to zero following extended sessions of this condition.

    View details for Web of Science ID 000167649500011

    View details for PubMedID 11317994

  • The principal components of response strength JOURNAL OF THE EXPERIMENTAL ANALYSIS OF BEHAVIOR Killeen, P. R., Hall, S. S. 2001; 75 (2): 111-134


    As Skinner (1938) described it, response strength is the "state of the reflex with respect to all its static properties" (p. 15), which include response rate, latency, probability, and persistence. The relations of those measures to one another was analyzed by probabilistically reinforcing, satiating, and extinguishing pigeons' key pecking in a trials paradigm. Reinforcement was scheduled according to variable-interval, variable-ratio, and fixed-interval contingencies. Principal components analysis permitted description in terms of a single latent variable, strength, and this was validated with confirmatory factor analyses. Overall response rate was an excellent predictor of this state variable.

    View details for Web of Science ID 000168966500001

    View details for PubMedID 11394483

  • Early development of self-injurious behavior: An empirical study AMERICAN JOURNAL ON MENTAL RETARDATION Hall, S., Oliver, C., Murphy, G. 2001; 106 (2): 189-199


    The early development of SIB in young children with developmental disabilities was examined by tracking over an 18-month period 16 school-age children who had recently started to show early SIB. Naturalistic observations were conducted in each child's classroom every 3 months, and the association between early SIB and environmental events was examined. Results showed that for the 4 children whose early SIB had escalated over this period, there was a significant association between early SIB and low levels of social contact across observation points, supporting models of the development of SIB. This association might be considered as a risk marker for the exacerbation of SIB. Implications of this finding for targeting early interventions for SIB are discussed.

    View details for Web of Science ID 000167861400008

    View details for PubMedID 11321609

  • Cognitive deterioration in adults with Down syndrome: Effects on the individual, caregivers, and service use AMERICAN JOURNAL ON MENTAL RETARDATION Oliver, C., Crayton, L., Holland, A., Hall, S. 2000; 105 (6): 455-465


    Individuals with Down syndrome (N = 49) who had participated in serial neuropsychological assessments were assigned to one of three groups comparable in level of premorbid mental retardation: those showing cognitive deterioration, those comparable in age but not showing cognitive deterioration, and those not showing cognitive deterioration but younger. Those experiencing cognitive deterioration were less likely to receive day services, had more impoverished life experiences, and required more support compared to groups without cognitive deterioration. When age was controlled for, cognitive deterioration was significantly positively associated with caregiver difficulties and service use and negatively associated with life experiences for the individual. Results suggest a potential role for caregiver difficulties in influencing life experiences of adults with Down syndrome showing cognitive decline.

    View details for Web of Science ID 000165585400002

    View details for PubMedID 11958199

  • Aggression and the termination of "rituals": a new variant of the escape function for challenging behavior? RESEARCH IN DEVELOPMENTAL DISABILITIES Murphy, G., MacDonald, S., Hall, S., Oliver, C. 2000; 21 (1): 43-59


    Aggression and stereotyped behaviors are not uncommon among people with intellectual disabilities and they are often treated separately as operant behaviors. In this single case study, it is argued that the function of a young woman's aggressive behavior appeared to be that of avoiding or escaping the termination of a chain of complex stereotyped behavior (or "ritual"). She became aggressive only when this chain of stereotyped behavior was terminated and the aggression appeared to extinguish when it no longer led to escape from the termination of the "ritual". It is suggested that this is an example of a complex interaction between two behaviors and that it illustrates the need for very careful analysis of the functions of challenging behavior. Furthermore, it is proposed that the lengthening list of variables already documented as determinants of challenging behavior (provision of attention (verbal and physical), mechanical restraint, sensory or tangible events, escape from demands or from social attention, denials, escape from intrusive medical procedures, escape from task difficulty) be lengthened to include the possibility of escape from (or avoidance of) the interruption of a chain of complex stereotyped behavior or "ritual".

    View details for Web of Science ID 000086123500004

    View details for PubMedID 10750165

  • Identification of early self-injurious behaviour in young children with intellectual disability JOURNAL OF INTELLECTUAL DISABILITY RESEARCH Murphy, G., Hall, S., Oliver, C., Kissi-Debra, R. 1999; 43: 149-163


    Very little is known about the early stages of self-injurious behaviour (SIB) in young children with developmental disabilities, even though there has been a great deal of research into the prevalence, assessment and treatment of well-established SIB in older individuals. In the present initial study, teachers in special schools for children under II years of age with severe intellectual disability and/or autism were asked to identify children who were beginning to show early self-injury (the index group). These children were then matched to classroom controls (of the same ability level and mobility), and teachers were interviewed about the children's behaviours and skills. The index children showed significantly more potential SIB than the control group children, but there was overlap between the groups in terms of percentage duration of potential SIB, suggesting that teachers do not find it easy to identify children with 'early' SIB. The index children's skills and problem behaviours, their sensory impairments and degree of autism did not differ significantly from those of the control group. When all the children showing any potential SIB were pooled together, it transpired that developmental age and degree of mobility were significantly correlated with percentage duration of SIB, suggesting that these characteristics may be important risk markers. The index children were also observed at 3-month intervals at school over the following 18 months and self-injury clearly escalated for some of the index children, while it did not do so for others. Using regression analysis, increases in SIB were shown to be associated only with the degree of concern expressed about the child's behaviour at time I by the teacher, no other variables predicting increases in SIB.

    View details for Web of Science ID 000081098200002

    View details for PubMedID 10392602

  • A molecular to molar analysis of communicative and problem behaviors RESEARCH IN DEVELOPMENTAL DISABILITIES Oliver, C., Hall, S., Nixon, L. 1999; 20 (3): 197-213


    Few studies have examined the relationship between communicative and problem behaviors that are already present in a behavioral repertoire. In this study, a detailed microanalysis of the antecedents and consequences of aggressive and communicative behavior of a 7-year-old boy was conducted. By using both descriptive and experimental methodologies, the data suggested that problem and communicative behavior were maintained on thin concurrent schedules of social negative reinforcement. A molar analysis of the descriptive data showed that the relative amount of time allocated to each behavior was a function of the relative amount of reinforcement that each behavior accrued. The implications of these findings are discussed in terms of conducting descriptive analyses and for enhancing the efficacy of interventions for problem behavior.

    View details for Web of Science ID 000080741800002

    View details for PubMedID 10372412

  • A clock not wound runs down BEHAVIOURAL PROCESSES Killeen, P. R., Hall, S., Bizo, L. A. 1999; 45 (1-3): 129-139
  • Watching the clock BEHAVIOURAL PROCESSES Fetterman, J. G., Killeen, P. R., Hall, S. 1998; 44 (2): 211-224
  • A four year prospective study of age-related cognitive change in adults with Down's syndrome PSYCHOLOGICAL MEDICINE Oliver, C., Crayton, L., Holland, A., Hall, S., Bradbury, J. 1998; 28 (6): 1365-1377


    While neuropathological studies indicate a high risk for Alzheimer's disease in adults with Down's syndrome, neuropsychological studies suggest a lower prevalence of dementia. In this study, cognitive deterioration in adults with Down's syndrome was examined prospectively over 4 years to establish rates and profiles of cognitive deterioration.Fifty-seven people with Down's syndrome aged 30 years or older were assessed using a battery of neuropsychological tests on five occasions across 50 months. Assessments of domains of cognitive function known to change with the onset of Alzheimer related dementia were employed. These included tests of learning, memory, orientation, agnosia, apraxia and aphasia. The individual growth trajectory methodology was used to analyse change over time.Severe cognitive deterioration, such as acquired, apraxia and agnosia, was evident in 28.3% of those aged over 30 and a higher prevalence of these impairments was associated with older age. The rate of cognitive deterioration also increased with age and degree of pre-existing cognitive impairment. Additionally, deterioration in memory, learning and orientation preceded the acquisition of aphasia, agnosia and apraxia.The prevalence of cognitive impairments consistent with the presence of Alzheimer's disease is lower than that suggested by neuropathological studies. The pattern of the acquisition of cognitive impairments in adults with Down's syndrome is similar to that seen in individuals with Alzheimer's disease who do not have Down's syndrome.

    View details for Web of Science ID 000077362600012

    View details for PubMedID 9854278

  • The treatment of severe self-injurious behavior by the systematic fading of restraints: Effects on self-injury, self-restraint, adaptive behavior, and behavioral correlates of affect RESEARCH IN DEVELOPMENTAL DISABILITIES Oliver, C., Hall, S., Hales, J., Murphy, G., WATTS, D. 1998; 19 (2): 143-165


    Severe self-injurious behavior (SIB) in people with mental retardation is difficult to treat when dangerously frequent or intense responding rules out functional analysis and interventions that permit free responding. This situation is common when restrictive devices, such as straight arm splints, are used. In this study, the effects of introducing flexion into a straight-arm splint, on SIB, self-restraint, adaptive behavior, and behavioral correlates of affect were examined for three individuals with severe mental retardation. Using single-case design methodology, for two individuals self-injury was reduced to zero, while the overall level of restriction was also significantly reduced. From the observed behavioral correlates of affect, there was no evidence of an increase in negative affect with the introduction of the new splint and the fading procedure, but there was evidence of an increase in positive vocalizations. Engagement in activities and social contact were not affected by the introduction of the new splint. The reasons for a decrease in SIB with a corresponding decrease in restriction in the absence of any manipulation of contingencies for SIB are discussed, with particular reference to stimulus control.

    View details for Web of Science ID 000072502600004

    View details for PubMedID 9547526

  • The neuropsychological assessment of age related cognitive deficits in adults with Down's syndrome JOURNAL OF APPLIED RESEARCH IN INTELLECTUAL DISABILITIES Crayton, L., Oliver, C., Holland, A., Bradbury, J., Hall, S. 1998; 11 (3): 255-272
  • A graphical method to aid the sequential analysis of observational data BEHAVIOR RESEARCH METHODS INSTRUMENTS & COMPUTERS Hall, S., Oliver, C. 1997; 29 (4): 563-573
  • Self-injurious behaviour and people with intellectual disabilities: Assessing the behavioural knowledge and causal explanations of care staff JOURNAL OF APPLIED RESEARCH IN INTELLECTUAL DISABILITIES Oliver, C., Hall, S., Hales, J., Head, D. 1996; 9 (3): 229-239

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