From: New York University

NYU/Yale research team explores neural basis of racial evaluation

A team of researchers from NYU and Yale have published a study that uses fMRI (functional magnetic resonance imaging) to explore the role of the amygdala in the unconscious evaluation of racial groups. The amygdala is a subcortical structure known to be involved in emotional learning and evaluation. The researchers found that subjects who showed a larger race evaluation bias, as detected in a mental association task and a startle response, also showed greater activity levels in regions of the amygdala while viewing unfamiliar Black compared with White faces.

NYU Cognitive Neuroscientist Elizabeth Phelps and Yale University Social Psychologist Mahzarin Banaji, along with their collaborators, have published this finding in a paper titled "Performance on Indirect Measures of Race Evaluation Predicts Amygdala Activation" that appears in the September issue of The Journal of Cognitive Neuroscience. The fMRI studies were performed by the NMR Research group in the Department of Diagnostic Radiology at Yale University School of Medicine under the direction of John C. Gore, Professor of Radiology and Applied Physics. The other co-authors are Kevin J. O'Connor, now at MIT's Department of Brain and Cognitive Sciences; William A. Cunningham, Yale University Department of Psychology; E. Sumie Funayama, Yale University Department of Psychology; J. Christopher Gatenby, Department of Diagnostic Radiology, Yale University Medical School.

The study consisted of two experiments. In the first, 14 White subjects (males and females) were placed in an MRI scanner and asked to view pictures of unfamiliar Black and White male faces with neutral expressions. For each picture, subjects were asked to press one button if the picture was the same as the preceding picture and another if the picture was different. While subjects made these judgments, activation of the amygdala (an indicator of blood flow) was measured.

After the imaging session, each subject participated in 3 additional, behavioral tasks:

1. The Implicit Association Test (IAT), a measure of the automatic association of positive and negative qualities to Black and White social groups. The measure is based on time to respond to pairings of Black+good/White+bad versus the opposite (Black+bad/White+good). The IAT may be sampled at www.yale.edu/implicit.

2. A startle response while viewing the unfamiliar Black and White faces. The startle response has previously been shown to be greater in the presence of stimuli that are considered to be more negative. Presenting random loud noises while subjects viewed the faces evoked the startle reflex. An electromyogram (EMG) was used to measure the magnitude of the startle eyeblink response, an early component of the startle reflex.

3. Consciously expressed attitudes towards race were measured using a survey called the Modern Racism Scale.

The researchers found that the strength of this amygdala activity to the unfamiliar Black versus White faces was related to unconscious social evaluation. That is, the stronger the activation in the amygdala, the stronger (a) the bias on the test of association between race (Black-White) and evaluation (good-bad) and (b) the degree to which subjects startled in the presence of Black versus White faces. These are two behavioral measures that are not under an individual's direct, conscious control. In contrast to these correlations, there was no relation between amygdala activation and conscious racial attitudes as assessed with the Modern Racism Scale.

The second experiment was identical to the first, with the exception that 12 different White subjects viewed pictures of famous and well-liked Black and White individuals. In this experiment, there was no consistent pattern of amygdala activation to the Black versus White faces and no relation between subjects' performance on the behavioral tasks and activity in the amygdala.

Yale Psychologist Mahzarin Banaji commented, "Evaluation in the common sense, that is, conscious evaluation, shows increases in positive regard among White Americans toward Black Americans. Yet, as social psychologists have documented for over a decade, implicit or unconscious evaluations continue to remain more negative. Unless one is socially isolated, it is not possible to avoid acquiring attitudes toward social groups. Yet, such evaluations can affect behavior in subtle and unintentional ways, showing a disturbing dissociation between our conscious values and beliefs and our less conscious, implicit preferences and evaluations. A similar discrepancy, labeled 'The American Dilemma' by Gunnar Mrydal over sixty years ago, is still with us. These experiments take a step forward in showing that there is indeed a connection between neural activity and unconscious race bias in mental activity."

NYU Neuroscientist Elizabeth Phelps said, "These results are significant because they link implicit measures of racial evaluation to neural mechanisms known to be important in everyday emotional learning and memory. In this study we chose to focus on the amygdala because of its known role in emotional learning and evaluation. We found that a given subject's amygdala activity in response to unfamiliar Black versus White faces is related to his or her performance on indirect measures of race evaluation. However, these results do not indicate that the amygdala 'causes' these behaviors. From these data, we cannot specify a particular behavioral function for the observed amygdala activation. The neural systems underlying implicit racial evaluation, and social group evaluation in general, are most likely extensive and expand beyond the amygdala. This work is a first step in our understanding of the neural basis of racial group evaluation."

Phelps and Banaji offered the following, "Our interpretation of the present study is that both amygdala activation as well as behavioral responses of race evaluation are reflections of social learning. It is common to think of the relationship between the brain and behavior as a one-way street, with brain function leading to behavior. This simple interpretation misses the complex interaction between the brain, behavior and experience. Just as behavior changes with experience, so does the brain. Widespread cultural evaluations of Black and White Americans, personal experiences with members of these groups, and one's own membership in these groups can all contribute to the magnitude of race evaluation bias. As our work shows, these experiences are also reflected in neural activity, as these measures are correlated.

In addition, we warn against interpretation of these results or measures as indicators of 'racism.' The measures used in this research should not and cannot be assumed to be a battery of tests that can be used to reveal an individual's hidden racism. It would be improper to use them in any selection or diagnostic context."

Elizabeth A. Phelps is an Associate Professor in the NYU Department of Psychology. She is also affiliated with NYU's Center for Neural Science. She can be contacted at: 212-998-8337 or at liz.phelps@nyu.edu.

Mahzarin R. Banaji is Professor of Psychology at Yale University. She can be contacted at 203-432-4547 or at mahzarin.banaji@yale.edu.

This article comes from Science Blog. Copyright 2004