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Brain correlates of cognitive processes underlying intertemporal choice for self and other

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Albrecht,  Konstanze
Department Cognitive Neurology, MPI for Human Cognitive and Brain Sciences, Max Planck Society;

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Albrecht, K. (2009). Brain correlates of cognitive processes underlying intertemporal choice for self and other. PhD Thesis, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig.


Cite as: http://hdl.handle.net/11858/00-001M-0000-0010-A21F-C
Abstract
Offered the choice between two monetary rewards, most people would prefer $10 today over $12 in a week, while only few would prefer $10 in a year over $12 in a year and a week. Many behavioral studies so far found that humans behave dynamically inconsistent and irrationally when making such monetary decisions called intertemporal choices. Psychological theories assume that special cognitive processes take place only when immediate gratification is possible, leading to such preference reversals. Self-theories suggest that these processes are special in decision making for oneself. Choices made for another person should not elicit the same processes and thus are assumed to be made in a more consistent manner regardless of immediacy. If this assumption holds true, it would have a high impact on explaining mechanisms important in decision delegation processes. In our first experiment, we investigated brain activation and choice behavior when intertemporal choices were made for oneself and for another, unknown person. We found that when an immediate reward was included in the choice set, intertemporal choices made for oneself were accompanied by activation in highly emotion- and reward-related areas, such as the pregenual anterior cingulate cortex, and the ventral striatum. However, none of these areas showed elevated activation when making such choices for another person. While this is in accordance with our hypothesis concerning the brain correlates of intertemporal choices for self and other, we did not find any behavioral differences in the choices the participants made for themselves and others: In both cases subjects inconsistently chose the smaller, but sooner, reward more often if it was available immediately. To investigate these discrepancies between choice and neural activation in detail, we splitted our sample into two groups, depending on subjects' individual discount values. Within the group of subjects who discounted future rewards more strongly, we could find the same differences in brain activation patterns between self and other as before. In accordance with 128 these brain activation differences, we also found behavioral differences between decisions for self and other in this group of strongly discounting subjects: They more often chose the larger, later reward for the other person than for themselves. This shows that at least subjects who discounted future rewards very strongly for themselves chose less impulsively for others. In our second study we investigated another variable influencing brain activation during such intertemporal choices: passivity. Can humans keep a “cool head” while watching what is decided for them without having any possibility to intervene? We used the same paradigm, this time letting our participants only observe choices being made for them or for another person. We found greater activity in the inferior frontal junction, intraparietal sulcus, and precuneus when participants observed choices yielding immediate compared to delayed rewards, for both self and other. A conjunction analysis with experiment 1 yielded that contrary to experiment 1, neither when making choices for oneself nor when making choices for another person, activation differences in the pregenual anterior cingulate cortex (pACC) and ventral striatum were found, indicating no differential involvement of these areas in today and delay trials when choices were observed. We concluded that immediate rewards were also special here, but relying on a more general mechanism, because their reception could not be actively influenced.