How unrealistic optimism is maintained in the face of reality

Abstract

Unrealistic optimism is a pervasive human trait that influences domains ranging from personal relationships to politics and finance. How people maintain unrealistic optimism, despite frequently encountering information that challenges those biased beliefs, is unknown. We examined this question and found a marked asymmetry in belief updating. Participants updated their beliefs more in response to information that was better than expected than to information that was worse. This selectivity was mediated by a relative failure to code for errors that should reduce optimism. Distinct regions of the prefrontal cortex tracked estimation errors when those called for positive update, both in individuals who scored high and low on trait optimism. However, highly optimistic individuals exhibited reduced tracking of estimation errors that called for negative update in right inferior prefrontal gyrus. These findings indicate that optimism is tied to a selective update failure and diminished neural coding of undesirable information regarding the future.

Figure 1

Task design. (a) On each trial participants were presented with a short description of one of 80 adverse life events and asked to estimate how likely this event was to occur to them. They were then presented with the average probability of that event occurring to a person like themselves, living in the same socio-cultural environment. For each event an estimation error term was calculated as the difference between the participant’s estimation and the information provided. The second session was the same as the first session. For each event an update term was calculated as the difference between the participant’s first and second estimations. (b,c) Examples of trials for which the participant’s estimate was (b) higher or (c) lower than the average probability. Here, for illustration purposes, the blue and red frames denote the participant’s response (either an overestimation or underestimation, respectively). The blue and red filled boxes denote information that calls for an adjustment in an (b) optimistic (desirable) or (c) pessimistic (undesirable) direction.

Figure 2

Behaviorally observed bias. (a) After receiving (desirable) information that presented an opportunity to adopt a more optimistic outlook, participants updated their estimations to a greater extent than after receiving (undesirable) information that called for a more pessimistic estimate. This asymmetric update was observed in 15 out of 19 participants. For group means see Supplementary Fig. 1a. (b) Betas indicating the association between update and estimation errors on an individual basis showed that estimation errors predicted update to a greater extent when participants received desirable information than when they received undesirable information. This asymmetry is observed in all 19 participants. For group means see Supplementary Fig. 1d.

Figure 3

Brain activity tracking estimation errors. Regions where BOLD signal tracked participants’ estimation errors on a trial by trial basis in response to desirable information regarding future likelihoods included (a) the left IFG and (b) bilateral MFC/SFG; (P < 0.05, cluster level corrected). (c) BOLD signal tracking participants’ estimation errors in response to undesirable information was found in the right IFG/precentral gyrus (P < 0.05, cluster level corrected). (d) Parameter estimates of the parametric regressors in both the left IFG and bilateral MFC/SFG did not differ between individuals who scored high or low on trait optimism. In contrast, in the right IFG a stronger correlation between BOLD activity and undesirable errors was found for individuals who scored low on trait optimism relative to those who scored high. Error bars (s.e.m.). * = P < 0.05, two-tailed independent sample t-test.

Figure 4

Optimism and brain activity tracking undesirable estimation errors. (a) Across individuals, the extent of the update bias (difference in update in response to desirable errors minus undesirable errors) correlated with how strong the peak voxel in the right IFG ROI correlated with undesirable errors (r₁₂ = 0.45). Participants showing the greatest optimistic bias in updating showed the weakest tracking of undesirable estimation errors. (d) Furthermore, participants who updated their estimates more in response to undesirable information showed a greater reduction in activity in the right IFG ROI the second time desirable information was presented, relative to the first (r = −0.47).