Read about the latest research published in Psychological Science:
Laura A. Harrison, Rene Hurlemann, and Ralph Adolphs
Monkeys that have amygdala lesions — a part of the brain involved in memory, emotion, and learning — show a tendency to approach stimuli that are normally considered threatening. The researchers examined whether amygdala lesions produce a general default bias to evaluate stimuli positively or a specific positivity bias — in this case, a face-approach bias. They asked control subjects and three subjects with rare bilateral amygdala damage to indicate the degree to which they found pictures of people with or without occluded central facial features trustworthy or threatening. Participants with amygdala damage had a greater tendency than did control participants to rate occluded faces as more approachable than whole faces. This suggests that amygdala legions lead to a general default bias to evaluate stimuli positively.
Arnold K. Ho, Steven O. Roberts, and Susan A. Gelman
Individuals of mixed Black and White descent are often characterized as being Black — a categorization bias known as hypodescent. In an examination of the factors influencing hypodescent, White adults were assessed for bias toward Whites or Blacks. Three weeks later, participants read an article indicating that race was genetically determined or that race had no genetic basis (a manipulation of perception of racial essentialism) before completing a task in which they categorized images of people as being White, Black, or Black-White multiracial. Racial essentialism had no impact on face categorization for participants low in intergroup bias, but it was related to increased classification of biracial individuals as Black for those high in intergroup bias. This finding sheds light on the way that motivational and cognitive biases lead to categorization bias.