Date of Award


Degree Type

Honors College Thesis



First Advisor

Mark J. Huff, Ph.D.

Advisor Department



Recently it has been shown that individuals have better memory for objects that have been touched by an individual with a contagious disease relative to an individual with a non-contagious disease or who is healthy (Gretz & Huff, 2019). This pattern has been suggested to occur due to the activation of the Behavioral Immune System (BIS)—an avoidance-based system designed to thwart sources of potential pathogens. The BIS has been suggested to operate through an evolutionary-based mechanism in which avoidance of pathogens increases the likelihood of survival, increasing reproductive success. Given this approach, an important question is how the activation of the BIS operates in older adults (60 + years of age), since older adults are past their reproductive prime, with many no longer having the physical capacity for reproduction. To evaluate the evolutionary BIS account, older adults watched a series of videos depicting an actor walking through a household scene and interacting with several objects. Prior to watching the videos, older adults were informed that the actor was either diagnosed with Influenza, a highly contagious disease, Cancer, a non-contagious disease, or was Healthy and not afflicted with any ailments. Following the videos, participants then completed a free-recall test where they were to retrieve the objects from the videos regardless if they were touched and a source-recognition test where they had to identify if a specific object was touched, not touched, or not in the videos at all. Recall of touched objects was greatest in the Influenza group, followed by the Cancer and Healthy groups, and source recognition for touched objects was only greater in the Influenza group relative to the Cancer and Healthy groups. Since touched-object recall was greater in the disease groups over the Healthy group, we instead argue for a health-preservation account over an evolutionary account of the BIS, in which BIS activation operates to promote longevity rather than promoting reproductive success.