Alcohol placebo effects on cognitive control of race bias : investigating neural mechanisms

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] The present study investigated the effects of alcohol expectancy on the exercise of control over racial bias. Participants consumed either a placebo alcohol beverage (fake vodka and tonic water) or a control beverage (tonic water), then performed the Weapons Identification Task (Payne, 2001) while brain activity was recorded with magnetic brain imaging. In this task, participants see a White face or a Black face followed by a gun or a tool. Participants are instructed to respond within half a second whether the object is a gun or a tool. Implicit racial biases cause participants to more quickly identify guns when they follow Black faces. Participants are also more likely to misidentify tools as being guns when they follow Black faces. Participants who had drank placebo vodka compensated for their expected intoxication by exercising more control over their responses. The accuracy of their responses were less influenced by the race of the preceding face. Additionally, placebo participants, compared to control participants, showed reduced interference from the racial cues after making mistakes, suggesting more effective maintenance of control despite errors. We replicated previous research of the regions of the brain responsible for detecting errors and exercising control over responses. One region, the anterior cingulate cortex, reacts when the participant makes errors. This is associated with later activity in another region, the lateral prefrontal cortex, which seems to execute control. This region was more active following errors in placebo participants than in controls, suggesting that it is responsible for their improved performance.