Towards an understanding of the perceptual foundations of prejudice

In-group identification is a central aspect of human social behaviour. There is evidence of the effects of in-group identification on different aspects of cognition but it is still unclear how in-group identification might affect basic perceptual mechanisms. Relying on an interdisciplinary perspective, this work investigates the extent to which in-group identification affects perception. This thesis explores the issue under three main themes. The first theme deals with the effect of in-group identification on perception using behavioural paradigms and relies on the measures of accuracy and reaction time as well as questionnaire measures of the strength of in-group identification. In this case, individuals show enhanced perceptual matching performance for stimuli associated with an in-group as opposed to the stimuli associated to rival and neutral groups. Moreover, the enhanced performance for in-group associated stimuli correlated with the satisfaction subcomponent of an in-group identification measure. The second theme aimed to gain a better understanding of the effects of in-group identification on both automatic (prosaccade) and inhibitory (antisaccade) aspects of explicit attentional orienting. In this case, the results provide evidence on the effect of in-group identification on the inhibitory control of overt attention, as well as on pupillary responses. The third theme examined the neural underpinnings of in-group identification effects on perception. Neural correlates of in-group biases were found in brain networks previously associated with social saliency, emotion and attention, notably the posterior superior temporal sulcus, the dorsolateral prefrontal cortex and anterior insula. Moreover, carrying out a perceptual matching task changed the functional connectivity between the anterior insula and the inferior frontal gyrus, and this change in connectivity was related to the magnitude of behavioural biases to the in-group. This suggests that such rapid changes in functional connectivity may provide a neural basis for the development of in-group favouritism. The overall findings across the different chapters confirm that in-group biases affect perceptual matching in a variety of ways and through a specific neural network. In general, the results are in line with the hypothesis that our perception favours stimuli linked to our in-group. The limitations and future possible lines of study are discussed.