Thesis (Ph. D.)--Florida State University, 2006. / Advisor: Jon Bailey, Florida State University, College of Arts and Sciences, Dept. of Psychology. Title and description from dissertation home page (viewed Sept. 13, 2006). Document formatted into pages; contains vi, 104 pages. Includes bibliographical references.

The prediction of Capaldi's sequential learning theory (i966, 1967, 1970) that resistance to extinction (Rn) increases as a function of the number of successive nonrewarded trials (N-length) conditioned to the instrumental response has recently been supported in a discrete-trials leverpress situation but not in a free-operant leverpress situation (Wolach & Ferraro, 1971). To investigate this discrepancy, 32 male albino rats were trained to leverpress in the presence of a visual sD under one of two N-length conditions (8 or 16) and one of four intertrial interval (ITI) conditions (5, 10, 15, or 30 sec.), the lowest of which corresponded to a freeoperant interresponse time. A subsequent extinction phase revealed that the 16 N-length group displayed greater Rn than the 8 N-length group at each ITI investigated on the dependent measures of extinction speed (p is less than .01) and trials to extinction criterion (p is less than .05). The results were interpreted as supporting the applicability of sequential theory to both discrete-trials and free-operant methodologies.

The investigation sought to examine resistance to extinction (Rn) as a function of previous experience with downward shifts in reward magnitude. It was suggested that previous research conducted within the framework of the Spence-Amsel frustration hypothesis and the sequential hypothesis failed to administer sufficient postshift trials to adequately establish the relationships that may exist. Under one condition, four groups of rats received twenty extinction trials following forty postshift trials. Under another condition, four groups were extinguished following eighty postshift trials. An inverse magnitude of reward effect occurred in the preshift phases, however, which prevented an adequate analysis of either the shift or the Rn data, This unexpected effect was discussed within the framework of Black's incentive-motivation interpretation of reinforcement.

An avoidance response was conditioned to three stimuli presented in serial order. Following conditioning, each group of subjects received a different treatment procedure. The group I procedure involved distributed CS trials, contingent, non-anxious CS terminations, and individualized treatment durations. Group 2 subjects received massed CS trials, non-contingent CS terminations, and non-individualized treatment durations. Group 3 subjects experienced distributed CS trials, contingent non-anxious CS terminations, and non-individualized treatment durations. Individual izing treatment duration (termination contingent upon operational ized measure of anxiety dissipation) was found to significantly hasten the extinction of avoidance responses. Implications for the effective practice of implosive therapy were discussed. Yoked control methods were criticized for confounding the variable of individualization of the yoked variable.

The present thesis examined extinction of conditioned fear in the developing rat. In the adult rat, the hippocampus is thought to be important for the context-specificity of extinction. Because the hippocampus is a late-maturing structure, it was hypothesised that context-modulation of extinction may be different across development. The first series of experiments investigated reinstatement of extinguished fear in the developing rat (Chapter 2). The results showed that P24 rats exhibited context-specific reinstatement. On the other hand, P17 rats did not exhibit reinstatement of extinguished fear following a US reminder treatment. The failure to see reinstatement in P17 rats was not due to the reminder treatment being ineffective in these rats because the same treatment alleviated spontaneous forgetting in rat this age. The second series of experiments then examined the renewal effect and GABAergic involvement in extinction in P24 and P17 rats (Chapter 3). It was observed that P24 rats displayed renewal whereas P17 rats did not. Also, pre-test injection of FG7142 recovered extinguished fear in P24 rats but not in P17 rats, even across a range of doses. This failure to see any FG7142 effect on extinction in P17 rats was not due to the lack of responsiveness to this drug in these rats because FG7142 was found to be effective in alleviating spontaneous forgetting in rats this age. The third series of experiments then examined the effect of temporary inactivation of the amygdala on extinction and re-extinction in the developing rat (Chapter 4). It was observed that extinction retention is impaired in both P24 and P17 rats if the amygdala is inactivated during extinction training. Interestingly, when a CS that had been previously extinguished and then re-trained was re-extinguished, re-extinction was amygdala-independent if initial extinction occurred at 24 days of age but amygdala-dependent if initial extinction occurred at 17 days of age. That is, amygdala involvement in re-extinction was dissociated across development. Taken together, these experiments provide strong evidence for fundamental differences in mechanisms underlying fear extinction across development. The implications of the findings were discussed in light of the theoretical and neural models of extinction.

Photocopy of typescript. / Bibliography: leaves 58-62. / Microfiche. / vii, 62 leaves ill. 29 cm

The present thesis examined extinction of conditioned fear in the developing rat. In the adult rat, the hippocampus is thought to be important for the context-specificity of extinction. Because the hippocampus is a late-maturing structure, it was hypothesised that context-modulation of extinction may be different across development. The first series of experiments investigated reinstatement of extinguished fear in the developing rat (Chapter 2). The results showed that P24 rats exhibited context-specific reinstatement. On the other hand, P17 rats did not exhibit reinstatement of extinguished fear following a US reminder treatment. The failure to see reinstatement in P17 rats was not due to the reminder treatment being ineffective in these rats because the same treatment alleviated spontaneous forgetting in rat this age. The second series of experiments then examined the renewal effect and GABAergic involvement in extinction in P24 and P17 rats (Chapter 3). It was observed that P24 rats displayed renewal whereas P17 rats did not. Also, pre-test injection of FG7142 recovered extinguished fear in P24 rats but not in P17 rats, even across a range of doses. This failure to see any FG7142 effect on extinction in P17 rats was not due to the lack of responsiveness to this drug in these rats because FG7142 was found to be effective in alleviating spontaneous forgetting in rats this age. The third series of experiments then examined the effect of temporary inactivation of the amygdala on extinction and re-extinction in the developing rat (Chapter 4). It was observed that extinction retention is impaired in both P24 and P17 rats if the amygdala is inactivated during extinction training. Interestingly, when a CS that had been previously extinguished and then re-trained was re-extinguished, re-extinction was amygdala-independent if initial extinction occurred at 24 days of age but amygdala-dependent if initial extinction occurred at 17 days of age. That is, amygdala involvement in re-extinction was dissociated across development. Taken together, these experiments provide strong evidence for fundamental differences in mechanisms underlying fear extinction across development. The implications of the findings were discussed in light of the theoretical and neural models of extinction.

Thesis (M.S.)--State University of New York at Binghamton, Department of Psychology, 2009. / Includes bibliographical references.

Thesis (Ph. D.)--State University of New York at Binghamton, Psychology Department, 2005. / Includes bibliographical references.

Thesis (M.S.)--State University of New York at Binghamton, Department of Psychology, 2008. / Includes bibliographical references.