Freiburg scientist decodes brain processes behind subconscious social evaluation
People form quick social judgments—often within milliseconds—about whether someone seems likeable or not. Dr. Bastian Schiller, a psychologist and neuroscientist affiliated with the University of Freiburg, together with a research team at the University of Basel, has identified the subconscious brain processes and their precise timing that underlie those split-second social evaluations. Their results, which reveal how the brain sequences discrete processing steps when evaluating in-group and out-group information, were published in the U.S. journal Proceedings of the National Academy of Sciences (PNAS).
The study used the Implicit Association Test (IAT) to probe rapid, unconscious social preferences. Participants were asked to respond to positive and negative words as well as to names linked to their own social group versus an opposing group. In one exemplar sample, soccer fans judged words such as “love” or “death” and accepted player names from their own team or the rival team while their brain activity was recorded with electroencephalography (EEG).
Schiller and collaborators—including Prof. Daria Knoch and Dr. Lorena Gianotti—focused on short-lived functional brain states known as microstates. Microstates are millisecond-scale intervals during which specific neuronal networks become active to perform particular processing steps. By tracing these microstates from stimulus presentation through to the motor response, the researchers were able to map the spatiotemporal progression of mental operations that produce the IAT effect.
Past IAT findings show that people generally take longer to pair positive concepts with an out-group (the incongruent condition) than with an in-group (the congruent condition). What remained unclear was whether this delay arises because the incongruent condition triggers extra processing steps, or because the same steps simply take longer to complete. Using electrical neuroimaging, Schiller and colleagues tracked the full sequence of mental processes underlying each trial and resolved this long-standing question.
The team identified seven distinct processing stages that span from the moment a stimulus appears to the generation of a response. Importantly, all seven processes appeared in the same temporal order in both congruent and incongruent conditions. The difference was not the addition of extra steps in the incongruent trials but rather the elongation of specific stages: an early perceptual processing phase and a later stage that implements cognitive control to select the appropriate motor response. In other words, the IAT effect is best explained by longer durations of particular processes rather than by extra processes in incongruent trials.
Beyond explaining average reaction time differences, the researchers found that the duration of the late cognitive-control stage contributed to individual differences in implicit bias. This insight links specific neural timing signatures to variability in how strongly people implicitly favor in-groups over out-groups.
These results demonstrate the power of modern EEG-based electrical neuroimaging to reveal the temporal organization of mental processes involved in social cognition. According to Schiller, this approach helps clarify both the origin and the time course of socially relevant brain activity. As a member of Prof. Markus Heinrichs’ group at Albert-Ludwigs University in Freiburg, Schiller is exploring how these findings could inform diagnostics and treatments for mental disorders that involve social-cognitive deficits.
Source: University of Freiburg
Image credit: Bastian Schiller / University of Freiburg.
Original research: Schiller B., Gianotti L. R. R., Baumgartner T., Nash K., Koenig T., & Knoch D. (Published online February 22, 2016). “Clocking the social mind by identifying mental processes in the IAT with electrical neuroimaging.” Proceedings of the National Academy of Sciences (PNAS). doi:10.1073/pnas.1515828113
Abstract (summary)
The researchers asked why responses in the Implicit Association Test are slower when pairing positive words with an out-group (incongruent condition) than with an in-group (congruent condition). Recording and analyzing scalp electrical activity in 83 participants, they identified seven sequential processing stages from stimulus onset to response. All seven stages occurred in the same order across conditions, but two stages—an early perceptual processing step and a late stage implementing cognitive control for motor selection—were prolonged in the incongruent condition. The duration of the late control stage accounted for part of the variability in individual implicit bias. These findings argue against explanations that attribute the IAT effect to additional processes in incongruent trials and support explanations based on longer processing times for specific stages. More broadly, the study illustrates how electrical neuroimaging can illuminate the timing and organization of mental processes in social cognition.