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Reward learning, decision-making, dopamine function

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Journal Articles


  • The neural basis of cultural differences in delay discounting PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES Kim, B., Sung, Y. S., McClure, S. M. 2012; 367 (1589): 650-656

    Abstract

    People generally prefer to receive rewarding outcomes sooner rather than later. Such preferences result from delay discounting, or the process by which outcomes are devalued for the expected delay until their receipt. We investigated cultural differences in delay discounting by contrasting behaviour and brain activity in separate cohorts of Western (American) and Eastern (Korean) subjects. Consistent with previous reports, we find a dramatic difference in discounting behaviour, with Americans displaying much greater present bias and elevated discount rates. Recent neuroimaging findings suggest that differences in discounting may arise from differential involvement of either brain reward areas or regions in the prefrontal and parietal cortices associated with cognitive control. We find that the ventral striatum is more greatly recruited in Americans relative to Koreans when discounting future rewards, but there is no difference in prefrontal or parietal activity. This suggests that a cultural difference in emotional responsivity underlies the observed behavioural effect. We discuss the implications of this research for strategic interrelations between Easterners and Westerners.

    View details for DOI 10.1098/rstb.2011.0292

    View details for Web of Science ID 000299897700003

    View details for PubMedID 22271781

  • A MECHANISM FOR REDUCING DELAY DISCOUNTING BY ALTERING TEMPORAL ATTENTION JOURNAL OF THE EXPERIMENTAL ANALYSIS OF BEHAVIOR Radu, P. T., Yi, R., Bickel, W. K., Gross, J. J., McClure, S. M. 2011; 96 (3): 363-385

    Abstract

    Rewards that are not immediately available are discounted compared to rewards that are immediately available. The more a person discounts a delayed reward, the more likely that person is to have a range of behavioral problems, including clinical disorders. This latter observation has motivated the search for interventions that reduce discounting. One surprisingly simple method to reduce discounting is an "explicit-zero" reframing that states default or null outcomes. Reframing a classical discounting choice as "something now but nothing later" versus "nothing now but more later" decreases discount rates. However, it is not clear how this "explicit-zero" framing intervention works. The present studies delineate and test two possible mechanisms to explain the phenomenon. One mechanism proposes that the explicit-zero framing creates the impression of an improving sequence, thereby enhancing the present value of the delayed reward. A second possible mechanism posits an increase in attention allocation to temporally distant reward representations. In four experiments, we distinguish between these two hypothesized mechanisms and conclude that the temporal attention hypothesis is superior for explaining our results. We propose a model of temporal attention whereby framing affects intertemporal preferences by modifying present bias.

    View details for DOI 10.1901/jeab.2011.96-363

    View details for Web of Science ID 000297609500005

    View details for PubMedID 22084496

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