Attending to Threat: Race-based Patterns of Selective Attention
A replication of Trawalter, Todd, Baird, & Richeson's (2008) design that includes a control for color as a disjunctive feature
A working example can be found at: http://graemeboy.com/trawalter/
There is overwhelming behavioral and physiological evidence that black men are stereotyped as violent and dangerous (Cottrell & Neuberg, 2005; Maner, Kenrick, Neuberg, Becker, Robertson, Hofer, et al., 2005). On this basis, Trawalter, Todd, Baird and Richeson (2008) hypothesized that if a black man's face were flashed alongside a white man's face on a gray homogenous background, a subject would pay attention sooner to the black man's face than the white man's face. The responses were measured using a dot-probe: After the images flashed, a dot appeared in the place of either one of the images, either on the left, or on the right. Subjects were asked to indicate, as quickly as possible, on which side the dot appeared. If the subject had been attending to one image more than the other, this would be reflected in a decreased response time when the dot appeared after that image.
In this study, the mean difference between the response times of both conditions in the first block, where the effect was found, was 10.4ms. The average standard deviation between these two conditions was 67ms. This yields a magnitude of effect of 0.16, which suggests a weak phenomenon (Cohen, 1992). This is surprising given the researchers' rationale for the hypothesis, which was that preattentive bias is adaptive for survival, and would occur in the black male face condition due to the strong associations between black men and violence.
Attention researchers have argued that salience can be caused by single features, such as motion, color, etc., and is not caused by conjunctions of features (Treisman & Gelade, 1980; Itti, Koch, & Neibur, 1998). Therefore, this exposes an alternative interpretation for the data presented by Trawalter et al. (2008). An interpretation more harmonious with prevailing theories of attention would be that the disjunctive features of one stimulus, such as its color, was salient enough to draw more attention than the other. Since these researchers did not control for disjunctive features in their experiment, we can never know if this was indeed the source of the response differences. In my design, which can be accessed by clicking the "Experiment" tab above, I replicate their design with an added control for color.
References
Itti, L., Koch, C. & Niebur, E. (1998). A model of saliency-based visual attention for rapid scene analysis. IEEE Transactions on Pattern Analysis and Machine Intelligence, 20, 1254-1259. Cottrell, C. A., & Neuberg, S. L. (2005). Different emotional reactions to different groups: A sociofunctional threat-based approached to "prejudice". Journal of Personality and Social Psychology, 88, 770-789. Maner, J. K., Kenrick, D. T., Neuberg, S. L., Becker, D. V., Robertson, T., Hofer, B., et al. (2005). Functional projection: How fundamental social motives can bias interpersonal perception. Journal of Personality and Social Psychology, 88, 63-78. Trawalter, S., Todd, A. R., Baird, A. A., & Richeson, J. A. (2008). Attending to threat: Race-based patterns of selective attention. Journal of Experimental Social Psychology, 44, 1322-1327. Treisman, A. M., & Gelade, G. (1980). A feature-integration theory of attention. Cognitive Psychology, 12, 97-136.