Date of Award

Spring 2015

Degree Type

Honors Project


College of Liberal Arts

First Advisor

Matt Olson


Psychology recognizes two distinct facets of the immune system: the biological immune system (BIO), covering all processes of the typical immune system, and the behavioral immune system (BEH), a set of cognitive, emotional, and behavioral responses to environmental stimuli. Research on this dual immune system indicates that each is capable of influencing the other (Schaller & Park, 2011). For example, perception of illness in others can activate the sympathetic nervous system (Schaller, Miller, Gervais, Yager, & Chen, 2010). Furthermore, evidence suggests that these two systems are capable of influencing moral judgment (Inbar, Pizarro, & Bloom, 2008). This study aims to further the overall understanding of the BEH and the manner in which it influences the BIO. Participants were recruited from college psychology courses in exchange for extra credit. These participants completed questionnaires regarding moral judgments and illness perception either before or after engaging in a visual stimulus task in which participants were prompted to select a face from a set of four using 32 different sets of photographs, each exposed for only 50 milliseconds. One face in each set of four appeared to be sick or engaged in sick behavior (coughing or sneezing). Saliva samples were taken from each participant before and after the questionnaire and visual stimulus task to measure and compare the levels of cortisol. Participants detected “sick” faces significantly above chance. Unfortunately, participants’ cortisol levels could not be analyzed due to error in the cortisol assay process. The face detection task did not affect moral judgments. Our primary results indicate that pathogen threat is salient even when the individual cannot completely process or analyze the stimulus. This research has many implications for medical treatment and decision making processes. More research is necessary to understand how the physiological activities of the BIO alone affect the processes of the BEH.