Date of Award
Master of Science (MS)
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.
Nelson, Matthew, "Reinstatement of Second-Order Fear" (2016). USC Aiken Psychology Theses. 27.