Summary: A new study reports the reward system in our brains may affect our judgments.
Source: Max Planck Institute.
We make judgements quite rationally or “by the gut”. Not only experience and relevant information play an important role, but also our preferences. A study by the Max Planck Institute for Metabolism Research in Cologne shows how the reward system in the brain conveys judgements affected by one’s own desires.
“In complex, confusing situations, we run the risk of making a biased judgement as soon as we prefer one conclusion over another,” explains Bojana Kuzmanovic, a scientist at the Max Planck Institute for Metabolism Research in Cologne. In her work, she investigated how people’s judgment is influenced by their wishful thinking.
In the study, volunteers were asked to estimate the average and personal risk of different negative events. They then learned the actual average risk and were able to adjust their own risk estimates accordingly. If the actual average risks were desirable (i.e. lower than initially estimated by the respondents), they were considered more than undesirable statistics.
Using an example, Kuzmanovic explains the phenomenon as follows: “By ignoring unpleasant information, we avoid drawing threatening conclusions. For example, we could neglect federal statistics, which indicate a higher risk of heart attack, because we think we have a particularly healthy lifestyle.
Desires activate reward system
During the survey the scientists recorded their brain activity using magnetic resonance tomography. They found that preferred judgements activate brain regions that otherwise react particularly strongly to rewards such as food or money. In addition, the scientists were able to show for the first time that the reward system in turn influenced other brain regions that are involved in conclusion processes. The stronger this neuronal influence was, the stronger the judgements of the study participants were determined by their wishes.
So, our desires and preferences influence our judgment without us consciously realizing it. The same brain systems that reinforce our efforts to maximize rewards such as food and money would also reinforce specific strategies for constructing judgements. Marc Tittgemeyer, who led the study, adds: “The influence of preferences is independent of expertise. We can benefit from this pleasant self-strengthening effect as long as our judgements do not have serious consequences. However, when making important decisions, we should be aware of our tendency to distort judgement and apply strategies to increase objectivity.”
Next, the researchers will investigate whether these and other reward-dependent behaviours are different in patients with metabolic diseases than in healthy individuals. Reward dependent brain circuits are closely linked to homeostatic circuits that regulate energy demand and metabolism based on saturation and hunger signals. Thus, if homeostatic networks are altered by disease, this could also affect reward-dependent brain areas and lead to more impulsive behaviour, for example.
Source: Dr. Marc Tittgemeyer – Max Planck Institute
Publisher: Organized by NeuroscienceNews.com.
Image Source: NeuroscienceNews.com image is in the public domain.
Original Research: Abstract for “Influence of vmPFC on dmPFC Predicts Valence-Guided Belief Formation” by Bojana Kuzmanovic, Lionel Rigoux and Marc Tittgemeyer in Journal of Neuroscience. Published September 12 2018.
Influence of vmPFC on dmPFC Predicts Valence-Guided Belief Formation
When updating beliefs about their future prospects, people tend to disregard bad news. By combining fMRI with computational and dynamic causal modeling, we identified neurocircuitry mechanisms underlying this optimism bias to test for valence-guided belief formation. In each trial of the fMRI task, participants (n = 24, 10 male) estimated the base rate (eBR) and their risks of experiencing negative future events, were confronted with the actual BR, and finally had the opportunity to update their initial self-related risk estimate. We demonstrated an optimism bias by revealing greater belief updates in response to good over bad news (i.e., learning that the actual BR is lower or higher than expected) while controlling for confounds (estimation error and personal relevance of the new information). Updating was favorable when the final belief about risks improved (or at least did not worsen) relative to the initial risk estimate. This valence of updating was encoded by the ventromedial prefrontal cortex (vmPFC) associated with the valuation of rewards. Within the updating circuit, the vmPFC filtered the incoming signal in a valence-dependent manner and influenced the dorsomedial prefrontal cortex (dmPFC). Both the valence-encoding activity in the vmPFC and its influence on the dmPFC predicted individual magnitudes of the optimism bias. Our results indicate that updating was biased by the motivation to maximize desirable beliefs, mediated by the influence of the valuation system on further cognitive processing. Therefore, although it provides the very basis for human reasoning, belief formation is essentially distorted to promote desired conclusions.
The question of whether human reasoning is biased by desires and goals is crucial for everyday social, professional, and economic decisions. How much our belief formation is influenced by what we want to believe is, however, still debated. Our study confirms that belief updates are indeed optimistically biased. Critically, the bias depends on the recruitment of the brain valuation system and the influence of this system on neural regions involved in reasoning. These neurocircuit interactions support the notion that the motivation to maximize pleasant beliefs reinforces those cognitive processes that are most likely to yield the desired conclusion.