Dissertations, Theses, and Capstone Projects

Date of Degree

2-2025

Document Type

Thesis

Degree Name

M.S.

Program

Cognitive Neuroscience

Advisor

David Johnson

Subject Categories

Cognitive Neuroscience

Keywords

Threat learning, fear conditioning, Pavlovian, Intolerance of Uncertainty, Response Coherence, individual differences

Abstract

Fear is a fundamental component of human learning, critical for survival, and extensively studied through Pavlovian conditioning paradigms (LeDoux & Pine, 2016). This thesis examines the interplay between stimulus-level uncertainty and individual differences in intolerance of uncertainty (IU) on threat-safety discrimination learning. Using a within-subject design, participants were conditioned to certain (100% reinforcement), uncertain (50% reinforcement), and safety (0% reinforcement) cues through the pairing of colored visual stimuli with aversive electrical shocks. Discrimination learning was assessed using both implicit (SCR) and explicit (self-reported US expectancy estimates and unpleasantness ratings) measures.

The present study (n = 102) replicated previous findings showing (1) better discrimination learning for certain vs uncertain threat cues and (2) divergent roles for two subscales (inhibitory and prospective) of the Intolerance of Uncertainty Scale (IU; Carleton, 2016) on threat safety discrimination learning (Johnson et al., 2023), as indexed by SCR. Specifically, higher inhibitory IU and prospective IU scores were associated with diminished vs enhanced discrimination, respectively. Additionally, these data extended previous research to show these effects occurred only for an uncertain but not certain threat cue. This pattern of results was not observed in the self-reported US expectancy data; that is, participants did not discriminate between uncertain vs certain threat cues in their US probability estimates, nor did IU or either of the IU subscales predict these estimates. However, participants with higher overall IU reported higher levels of dislike for the uncertain vs certain threat cue. Finally, we showed only mild correlations (response coherence) between implicit and explicit measures here, in line with previous studies supporting a dual- or multiple-process model for fear/threat. Taken together, these findings illustrate a critical role for trait measures to partially explain inter-individual variability observed in threat acquisition processes and point to a potential target for new or optimized clinical therapies for stress and anxiety disorders.

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