Although it involves just a few test subjects, a pencil-chomp study presumably provides insight into the hard-to-measure subject of race bias.
“The Influence of Facial Feedback on Race Bias,” Tiffany A. Ito, Krystal W. Chiao, Patricia G. Devine, Tyler S. Lorig, and John T. Cacioppo, Psychological Science, vol. 17, no. 3, 2006. (Thanks to investigator Frank Pyne for bringing this to our attention.) The authors, variously at University of Colorado, University of Chicago, University of Wisconsin-Madison, and Washington and Lee University, report:
Participants were surreptitiously induced to smile through holding a pencil in their mouth while viewing photographs of unfamiliar Black or White males or performed no somatic configuration while viewing the photographs…
[The study was conducted on] Thirty-three (6 Asian American, 2 Hispanic American, 22 Caucasian American, 3 other) and 40 (3 Asian American, 4 Hispanic American, 29 Caucasian American, 4 other) undergraduates.