Recently, Anneli Jefferson reported a behavioral study investigating the optimism bias by using a belief update paradigm inspired by Sharot et al. (2011). The findings show that when confronted with new information, people adjusted their initial risk estimates for undesirable future events to a greater extent when this information supported more positive outlooks than when it suggested a higher risk for future hazards (Kuzmanovic et al., under revision). Moreover, this asymmetry in updating was greater for judgments relating to oneself than for those relating to similar others, and was moderated by individual differences in trait optimism.
While this result shows that a biased use of information provides individuals with a way of maintaining optimism in the face of conflicting evidence, thereby protecting them from unwelcome expectations, the purely behavioural study does not tell us much about what mechanisms underlie the differential information use we see in the optimism bias. We learn little about the exact psychological process underlying judgement formation. Theoretical accounts assume that both cognitive and motivational mechanisms underlie optimistic thinking and reasoning, but empirical evidence is scarce. These covert processes can be elucidated by using functional magnetic resonance imaging to identify brain regions that are specifically involved in forming optimistically biased judgements.
We expected that the outcome of the update itself, and not only the consideration of estimation errors, should have an affective value for the judging subject. Specifically, we expected that updates after desirable information resulting in more positive future outlooks would be associated with pleasure, but not so updates after undesirable information leading to more negative future outlooks. Thus, we correlated the whole brain activity with the size of updates in the course of the experiment separately for desirable and undesirable information and for estimations relating to self and other. The main finding was that the activity in the ventromedial prefrontal cortex (vmPFC) increased both with larger favourable updates and with smaller unfavourable updates. The involvement of this region therefore reflects the positive value of a favourable future outlook that is generated both by large updates after desirable information and refraining from updates after undesirable information. In good accordance with this finding, the vmPFC has been consistently associated with the subjective value of emotional stimuli and rewards in previous studies (D'Argembeau, 2013; Levy and Glimcher, 2012; Winecoff et al., 2013).
The differential activity pattern in the vmPFC thus supports the assumption that optimistic expectations towards the future entail a hedonic value that may interact with and influence other domains of cognition leading to differential information use within the judgment formation.
D'Argembeau, A. (2013). On the role of the ventromedial prefrontal cortex in self-processing: the valuation hypothesis. Front Hum Neurosci 7, 372.
Kuzmanovic, B., Jefferson, A., Timmermanns, B., and Vogeley, K. (in preparation). Ventromedial prefrontal activity reflects the emotional value of self-related optimistic belief updates.
Kuzmanovic, B., Jefferson, A., and Vogeley, K. (under revision). Self-specific optimism bias in belief updating is associated with high trait optimism. Journal of Behavioral Decision Making.
Levy, D.J., and Glimcher, P.W. (2012). The root of all value: a neural common currency for choice. Curr Opin Neurobiol 22, 1027-1038.
Sharot, T., Korn, C.W., and Dolan, R.J. (2011). How unrealistic optimism is maintained in the face of reality. Nat Neurosci 14, 1475-1479.
Winecoff, A., Clithero, J.A., Carter, R.M., Bergman, S.R., Wang, L., and Huettel, S.A. (2013). Ventromedial prefrontal cortex encodes emotional value. J Neurosci 33, 11032-11039.