Bias on the Brain: A Neural Basis for Prejudice

The modern era of biology has repeatedly forced us to deal with questions of determinism and responsibility. Advances in neuroscience cut to the very core of this issue as the underlying brain processes that account for our most basic thoughts, feelings, and actions are illuminated. Scientific understanding of the central nervous system leads us to the question: if we know that a particular part of the brain (or combination of chemicals, or type of neurological injury) can induce a particular behavior, is a person culpable for that behavior? Is he acting under his own free will, or is he merely under the inescapable influence of biology? The answer is not always clear.

One particularly problematic area concerns the neurological underpinnings of bias. If racism, sexism, and other forms of prejudice are merely the result of the firing of neurons, are these individuals still responsible for their aberrant beliefs? Scientific evidence and ethical considerations suggest the answer is still a resounding “yes.”

The Implicit Association Test (IAT). Courtesy of www.nsf.gov

Psychological testing introduced some of the earliest evidence that certain biases may be more deeply rooted in the mind than previously thought. One way of measuring bias is the Implicit Association Test (IAT), which was first described in 1998 by researchers at the University of Washington, Seattle [1]. The IAT asks subjects to associate a word, name, or image with any of a range of possible answers. To take a benign example, if the word “dog” appears on the computer screen, the subject might be asked to click on either “friendly” or “threatening.” The interesting result is not necessarily which answer was selected, but rather how quickly the subject selected it. The fundamental assumption of the IAT, which has been supported by various methods of testing, is that a more rapid association between a noun and an attribute (such as “dog” and “friendly”) indicates the subject’s actual (or implicit) belief (that dogs are friendly). The IAT is therefore able to suggest the subject’s unconscious or automatic beliefs about a particular topic.

The application of the IAT to questions of prejudice is obvious. When asked to associate a word or image linked to an individual of a different racial, ethnic, or gender group, the IAT reveals surprising degrees of unconscious bias and stereotyping. Many people will automatically associate a person who is somehow different from themselves with negative attributes.

Interestingly, repeated studies have shown that many individuals are actually more biased than they think they are, a troubling result that indicates the extent to which social influences can affect our deepest attitudes and assumptions. (To take the test yourself, go to Project Implicit at http://implicit.harvard.edu.) However, in general, an individual’s score on the IAT correlates fairly well with his or her self-reported degree of prejudice [2]. People who say they are more prejudiced will generally have corresponding implicit assumptions about members of other racial or gender groups.

Brain imaging studies support this conclusion, and have even pinpointed certain areas of the brain that appear to be associated with these automatic thought processes. A group of researchers at the U.S. National Institute of Neurological Disorders and Stroke used functional MRI imaging to examine subjects while they answered questions on the IAT related to race and gender [3]. When subjects gave automatic responses, three areas of the brain were most active: prefrontal cortex, anterior cingulate cortex, and amygdala. The prefrontal cortex is associated with higher-order thoughts and the coordination of behaviors that are appropriate given an individual’s goals and social situation. The anterior cingulate cortex and amygdala are both responsible for emotional responses, especially fear and anger.

The researchers conclude that two different brain processes are at work in the case of bias: first, there is an emotional response, driven by deeper brain regions such as the amygdala, that tends to promote a negative bias; meanwhile, higher brain regions, such as the prefrontal cortex, act to suppress these automatic biases. Interestingly, the researchers found similar results when asking partisan individuals to respond to political questions and faces of politicians – in other words, a person’s political behavior is largely driven by bias and emotion rather than logic and reason [4].

The amygdala provides the emotional response to seeing a dog. Courtesy of www.sxc.hu

The hypothesis that naturally arises from these findings is that a person’s degree of prejudice is mediated by how well her more base emotional reactions are modified and controlled by her higher mental processes, those processes associated with proper behavior and rational thought. Current information suggests that this hypothesis is essentially correct. Functional brain imaging studies, such as the one discussed above, show that different parts of the prefrontal cortex are active in individuals who give implicit versus explicit responses on the IAT, lending support to this hypothesis. Similarly, psychological studies indicate that people are able to suppress implicit bias for a variety of reasons, especially when they expressly desire to do so [5].

If bias can be traced to the relationships between different parts of the brain, are people still responsible for it? Scientists who work in this field offer a virtually unanimous affirmative response for a variety of reasons [6]. First, as discussed above, countless studies demonstrate that implicit and explicit responses are often different; most people are able to control their automatic biases, especially when society encourages them to reconsider and control these basic responses. Second, many researchers are quick to point out the difference between bias and prejudice: even when a particular bias is automatic, it takes a fair amount of conscious work to convert that bias into prejudice against a particular group of people.

Individuals can learn to control their biases: either to override them, or to turn them into active discrimination and hatred. In both cases, the decision is conscious and totally independent of implicit biases. A deeply prejudiced individual is therefore responsible, in some meaningful way, for that behavior. Although neuroscience can shed light into the functionings of the mind, it does not erase responsibility for our actions.

References:

1. Greenwald AG et al. “Measuring individual differences in implicit cognition: the Implicit Association Test.” Journal of Personality and Social Psychology (1998). 74(6): 1464-1480.

2. Hofmann W et al. “A meta-analysis on the correlation between the Implicit Association Test and explicit self-report measures.” Personality and Social Psychology Bulletin (2005). 31(10): 1369-1385.

3. Knutson KM et al. “Neural correlates of automatic beliefs about gender and race.” Human Brain Mapping. 28 Nov. 2006.

4. Knutson KM et al. “Politics on the brain: an fMRI investigation.” Social Neuroscience (2006). 1(1): 25-40.

5. Legault L et al. “On the self-regulation of implict and explicit prejudice: a self-determination theory perspective.” Personality and Social Psychology Bulletin. 17 April 2007.

6. Vedantam, Shankar. “See no bias.” The Washington Post, 23 Jan. 2005.