Electronic Theses and Dissertations

Date of Award


Document Type


Degree Name

Ph.D. in Psychology



First Advisor

Kenneth J. Sufka

Second Advisor

John M. Rimoldi

Third Advisor

John N. Young

Relational Format



Cognitive bias is a phenomenon that presents in individuals suffering from anxiety and depression where anxious individuals tend to adopt a more pessimistic interpretation of ambiguous aversive stimuli and depressed individuals tend to adopt both a more pessimistic interpretation of ambiguous aversive stimuli as well as a less optimistic interpretation of ambiguous appetitive stimuli. Such biases have been pharmacologically reversed using anxiolytics and antidepressants. The chick anxiety-depression model has observed more pessimistic-like and less optimistic-like behavior in approach/avoidant runway performance to ambiguous aversive and ambiguous appetitive stimuli, respectively. Further, both types of cognitive biases have been reversed in a White Leghorn strain using the antidepressant imipramine. One goal of the current study was to examine whether cognitive biases of more pessimism and less optimism would manifest in a pattern reflecting the stress vulnerability and resiliency in Black Australorp and Production Red strains, respectively. Non-isolated and isolated (90 min) chicks were tested in a straight alley maze under an ambiguous appetitive (75c:25o) and an ambiguous aversive (25c:75o) stimulus cue with start and goal latency and distance traveled as the dependent measures. Less optimistic-like behavior and more pessimistic-like behaviors were observed under the 75c:25o and 25c:75o stimulus cues, respectively. Interestingly, stress vulnerability on cognitive bias in BAs presented primarily in non-isolated conditions. A second goal of the current study was to examine if cognitive biases in BAs could be reversed in a manner that parallels the strain's differential drug responsivity, whereby ketamine would reverse and imipramine would fail to reverse cognitive bias. Non-isolated and isolated (90 min) chicks received an administration of either a physiological saline vehicle, 10.0 mg/kg of imipramine and 10.0 mg/kg of ketamine prior to maze testing which follothe same procedure as Experiment 1. Imipramine and ketamine failed to produce a significant antidepressant effect on DVoc rates in isolated chicks. Consistent with the inability to detect a significant ketamine effect, more pessimistic-like behavior was not reversed under the 25c:75o stimulus cue. Surprisingly, not only did the 75c:25o stimulus cue fail to show less optimistic-like behavior, but the observed effects were in the opposite direction. The absence of a ketamine effect may be due to experimental procedures necessary to quantify cognitive bias. Collectively, the current study identified cognitive biases of more pessimism and less optimism in a stress-vulnerable Black Australorp and a stress-resilient Production Red strain. Surprisingly, the most robust strain difference presented between non-isolated conditions. These findings strengthen homologies between clinical populations by providing validative support to the identification of a stress-vulnerable and stress-resilient strain which further validate the chick anxiety-depression model as a neuropsychiatric simulation.


Emphasis: Experimental Psychology

Included in

Psychology Commons



To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.