Frontal brain damage makes decisions less biased

Learning from reinforcement is a classic way to study how brain areas contribute to adaptive behaviour. The most frontal parts of the brain probably contribute at a very high, abstract level. In this study (Manohar et al. Cortex 2021), we asked how confident people are in what they have learned.

Underside of a human brain showing a part of the ventromedial prefrontal cortex.

Healthy people are biased by previous choices, and by competing information, when making these “meta-cognitive” estimates. However, patients with selective damage to the medial prefrontal cortex lacked these biases. They were effectively better at this.

One patient had lesions on both the left and the right side, and he outperformed all the 47 other people in the study!