Term of Award

Spring 2025

Degree Name

Master of Science in Experimental Psychology (M.S.)

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Department

Department of Psychology

Committee Chair

Joshua Herrington

Committee Member 1

Wendy Wolfe

Committee Member 2

Jonathan Roberts

Abstract

The long-standing assumption that predator odor avoidance in rodents is an innate survival mechanism has shaped decades of behavioral neuroscience research and underpins translational models of post-traumatic stress disorder (PTSD). However, developmental systems theory (DST) posits that behaviors emerge from dynamic interactions across physiological and environmental systems over time, rather than from fixed genetic programs. This study critically evaluates the developmental plasticity of predator scent aversion by examining whether early-life exposure to red fox urine (a natural predator odor) can attenuate avoidance behaviors in Long–Evans rats. Seventy-one rats were bred into three conditions: Control (no exposure), Partial (exposure from birth), and Full (exposure to dam beginning two weeks before breeding). Behavioral testing at three developmental stages (Early, Adolescent, and Adult) included an emergence test assessing latency and duration of exploratory behavior in the presence of fox urine, and a Y-maze test measuring preference between fox and non-predator (doe) urine. Repeated-measures linear mixed models and logistic regressions were used to assess effects of condition, age, and interactions on various behavioral outcomes. Results showed minimal avoidance of fox urine across all conditions, with some rats even interacting with or carrying the predator-scented stimulus. Only one interaction (Full × Adolescent) reached statistical significance, and one additional trend (Partial × Adult) approached significance. Y-maze results revealed no significant preference or aversion, and testing order rather than condition significantly predicted movement-based metrics. Together, these findings suggest that fox urine does not reliably elicit fear or avoidance, even in scent-naïve rats, challenging the assumption of innate predator odor aversion. The data support a developmental systems perspective: fear responses to predator odors are not universally hardwired but contingent on developmental context and experience. This reframing has important implications for both the interpretation of behavioral assays in rodents and the validity of predator odor as a model for innate fear or trauma. Future research should further explore individual variability, critical periods, and the integration of neurobiological markers to understand the complex ontogeny of defensive behaviors.

Research Data and Supplementary Material

No

Download

Share

COinS