April 22, 2004

Subconscious bias skews perceptions

By Pat Vaughan Tremmel

Subconscious — or implicit — bias may cause even well-meaning whites to look at identical facial expressions of African Americans and European Americans and see greater hostility in the African American faces, according to new Northwestern research.

Or if the expression on a racially ambiguous face — combining African American and European American features — is hostile, whites are more likely to identify it as African American, according to related research.

The unusual research, by Kurt Hugenberg, assistant professor, Miami University, and Galen Bodenhausen, professor of psychology at Northwestern, strongly suggests implicit bias distorts perception of facial cues so important to effective communication and perpetuates stereotypes. A self-fulfilling prophecy may be among the most troubling consequences.

“If stereotypes color something as basic as face perception, then the downstream consequences may be considerable,” said Bodenhausen. “Perceived hostility will at best promote avoidance — or worse, may foster reciprocation.”

While implicit bias has been the focus of a variety of research, Bodenhausen’s work is rare in that it uses changing computer-generated facial expressions to tease out how deeply-rooted prejudice distorts perceptions. Most experiments on face perception use still photographs as stimuli, despite the dynamic nature of facial displays in real-life interactions.

The two companion studies are titled “Facing Prejudice: Implicit Prejudice and the Perception of a Facial Threat” (Psychological Science, 2003) and “Ambiguity in Social Categorization: the Role of Prejudice and Facial Affect in Race Categorization” (Psychological Science, 2004).

The first experiment included 24 European Americans who observed four movies with computer-based faces of whites and African Americans — matched precisely for both facial structure and expression — that morphed from unambiguous hostility to unambiguous happiness. The target’s expression was ambiguous, somewhere between hostile and friendly, for a substantial period of time.

Those high in implicit bias, measured by a simple word categorization test, saw hostility as lingering longer and appearing more quickly in the faces of African Americans.

Twenty-four European Americans also participated in the experiment to identify the race of racially ambiguous faces. Fifteen computer-generated faces were morphed to contain racially ambiguous facial structures, skin tone and hairstyles and to create two expressions, one clearly happy and the other clearly hostile. Those measuring high in implicit prejudice tended to categorize faces with hostile expressions as African American.

Both experiments show how stereotypes can color early and most immediate perceptions of other people.