Patterns of neural activity associated with honest and dishonest moral decisions

Abstract

What makes people behave honestly when confronted with opportunities for dishonest gain? Research on the interplay between controlled and automatic processes in decision making suggests 2 hypotheses: According to the "Will" hypothesis, honesty results from the active resistance of temptation, comparable to the controlled cognitive processes that enable the delay of reward. According to the "Grace" hypothesis, honesty results from the absence of temptation, consistent with research emphasizing the determination of behavior by the presence or absence of automatic processes. To test these hypotheses, we examined neural activity in individuals confronted with opportunities for dishonest gain. Subjects undergoing functional magnetic resonance imaging (fMRI) gained money by accurately predicting the outcomes of computerized coin-flips. In some trials, subjects recorded their predictions in advance. In other trials, subjects were rewarded based on self-reported accuracy, allowing them to gain money dishonestly by lying about the accuracy of their predictions. Many subjects behaved dishonestly, as indicated by improbable levels of "accuracy." Our findings support the Grace hypothesis. Individuals who behaved honestly exhibited no additional control-related activity (or other kind of activity) when choosing to behave honestly, as compared with a control condition in which there was no opportunity for dishonest gain. In contrast, individuals who behaved dishonestly exhibited increased activity in control-related regions of prefrontal cortex, both when choosing to behave dishonestly and on occasions when they refrained from dishonesty. Levels of activity in these regions correlated with the frequency of dishonesty in individuals.

Fig. 1.

Task sequence: The subject (1) observes the trial's monetary value and privately predicts the outcome of the upcoming coin flip, (2) records this prediction by pressing 1 of 2 buttons (No Opportunity condition) or presses one of these buttons randomly (Opportunity condition), (3) observes the outcome of the coin flip, (4) indicates whether the prediction was accurate, (5) observes the amount of money won/lost based on the recorded prediction (No Opportunity) or the reported accuracy (Opportunity), and (6) waits for the next trial. Op, opportunity. Button presses in response to screen 2 in the Opportunity condition and screen 4 in the No Opportunity condition control for motor activity.

Fig. 2.

Distribution of self-reported percent Wins in the Opportunity condition. Subjects were classified into 3 groups based on the probability that they behaved dishonestly. Mean percent Wins in the No Opportunity condition was 50%. See Table 1 for reaction time data.

Fig. 3.

Brain regions exhibiting increased activity in the Opportunity condition, as compared with the No Opportunity condition, broken down by group (honest vs. dishonest) and outcome type (win vs. loss). BA, Brodmann area. fMRI data are projected onto a reference anatomical image. (A) Increased activity in bilateral DLPFC is associated with decisions to lie (Opportunity Wins > No-Opportunity Wins) in dishonest subjects. (B) Increased activity in bilateral ACC/SMA, DLFPC, VLPFC, DMPFC, and right parietal lobe is associated with decisions to refrain from lying (Opportunity Losses > No-Opportunity Losses) in dishonest subjects. (C) Increased activity in bilateral VLPFC is associated with decisions to accept honest wins (Opportunity Wins > No-Opportunity Wins) in honest subjects. No significant effects were observed in association with decisions to refrain from lying (Opportunity Losses > No-Opportunity Losses) in honest subjects.

Fig. 4.

A stepwise regression model accounts for the frequency of dishonest behavior in individuals (as indexed by percent Wins in the Opportunity condition) based on fMRI BOLD signal in 5 brain regions (L DLPFC, DMPFC, R parietal lobe, and bilateral VLPFC). Model R² = 0.79; Adj. R² = 0.74, r = 0.89, n = 35, P < 0.0001 (See Table S3).