Date of Award


Degree Type


Degree Name

Master of Science (MS)



First Advisor

Edward Callen

Second Advisor

Meredith Elzy

Third Advisor

Alexandra Roach


The purpose of this study was to determine if, after conditioning and extinction of a second-order stimulus, reinstatement of extinguished fear could be produced. The findings of Holmes et al. (2014) do not support reinstatement of second-order fear following post-extinction presentation of the unconditioned stimulus (US). The present study provides a second attempt at uncovering reinstatement following extinction of second-order conditioning. Rat subjects were randomly assigned to 5 groups (n=12), which received first- and second-order conditioning with Light and Tone counterbalanced. Responding to the second-order stimulus (S2) was extinguished through S2-alone presentations for all but the control subjects (Group NE-NR). This group did not receive extinction or reinstatement and served as the baseline of fear conditioned to S2. Comparisons made between Group NE-NR and subjects presented the US (Group US-alone) or additional first-order pairings (Group S1-US) indicated similar levels of freezing and thus reinstatement. Lower levels of freezing were noticed in Group S2-S1 and Group S1-alone and indicated effective extinction through presentation of S2 alone, and a lack of reinstatement for these groups. The clinical applications of these results are discussed.