Diss.--Hamburg, 2000. / Bibliogr. p. [311]-331. Index.

This thesis is concerned with the effects of varying the intensity of one element of a compound stimulus while holding the other constant in an experiment employing Kamin’s (1964) design for showing the “perceptual or associative block" in the conditioned emotional response situation. The question of whether Pavlovian "overshadowing” or Hullian "summation” usually obtains during classical compound conditioning is examined. The major findings were (1) that the degree of blocking is a monotonic function of the intensity of the first conditioned element; (2) that rate of conditioning to a compound stimulus is a monotonic function of the intensity of the varied element; and (3) that Hullian summation is the usual case in compound conditioning but that Pavlovian overshadowing occurs when one element is relatively much weaker than the other in terms of speed of conditioning. / Thesis / Master of Arts (MA)

Univ., Diss. u.d.T.: Rüting, Torsten: Pawlows Bestimmung und Vermächtnis im Diskurs um die Entwicklung von Disziplin während der Modernisierung Rußlands und der Schöpfung der Sowjetzivilisation--Hamburg, 2000. / Literaturverz. S. [311] - 331.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1940. / Typescript. Includes abstract and vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 47-49).

This study investigated whether adaptation (lessoned emotional reactivity) to electric shock is specific to the environmental situation in which experience with shock is had. The conditioned emotional response (CER) described by Estes and Skinner was utilized, with rats as subjects. Four experimental groups received experience with shock in four different environments, graded in terms of their similarity to the environment in which the CER was later to be measured; a control group received no shock before CER training. The four experimental groups acquired the CER less rapidly than did the control group, but did not differ among themselves. The effect thus appeared to be nonspecific; however, some aspects of the data suggested that the effect may not in fact be attributable to an adaptation process. / Thesis / Master of Arts (MA)

Pavlov (1927) first reported that following appetitive conditioning of multiple stimuli, extinction of one CS attenuated responding to others which had not undergone direct extinction. Four experiments with rat subjects investigated potential mechanisms of this secondary extinction effect. Experiment 1 assessed whether secondary extinction would be more likely to occur with target CSs that have themselves undergone some prior extinction. Two CSs were initially paired with shock. One CS was subsequently extinguished before the second CS was tested. The target CS was partially extinguished for half the rats and not extinguished CS for the other half. A robust secondary extinction effect was obtained with the non-extinguished target CS. Experiment 2 investigated whether secondary extinction occurs if the target CS is tested outside the context where the first CS is extinguished. Despite the context switch secondary extinction was observed. Extinction of one CS was also found to thwart renewal of suppression to a second CS when it was tested in a neutral context. Experiment 3 examined whether secondary extinction can be attributed to mediated generalization caused by association of the CSs with a common US during conditioning. Rats received conditioning with three CSs and then extinction with one of them. Secondary extinction was observed with a shock-associated CS when the extinguished CS had been associated with either food pellets or shock, suggesting that secondary extinction is not US-specific and is thus not explained by this mediated generalization mechanism. Experiment 4 examined whether intermixing trials with the two stimuli during conditioning is necessary for secondary extinction to occur. Rats were either conditioned with intermixed trials as in Experiments 1-3, or with blocked trials of each CS presented in conditioning sessions separated by a day. Secondary extinction was observed only in the former condition. The results are consistent with the hypothesis that CSs must be associated with a common temporal context for secondary extinction to occur.

The safety signal hypothesis suggests that during the absence of stimuli predicting impending shock, the organism is not fearful. The stimuli which predict the absence of shock are therefore called safety signals. The purpose of the present study was to investigate some critical properties of safety signals. Such stimuli in an avoidance or escape situation, according to the opponent process model, are expected to acquire hedonic value opposite to shock. This study examined differences in conditioning variables between safety signals predicting different intensities of shock, and between safety signals present in procedures using predicted shock, and procedures using unpredicted shock. Additionally, the effects of inescapable unpredicted shock with no safety signals present were examined. The general procedure involved exposing pigeons to aversive Pavlovian conditioning and subsequently autoshaping these birds to stimuli which had predicted safety in the aversive situation. Dependent measures included trials to acquisition of the autoshaped response and subsequent rate of keypecking. In the six experimental groups, pigeons were repeatedly and inescapably shocked at either 30 or 90 volts. Each individual 0.5 sec shock was (a) predicted by a specific stimulus or (b) not predicted. Additionally and explicitly unpaired with the shock, a safety signal was presented. For each voltage level, a control group was repeatedly shocked with no stimuli presented at any time. Control groups were included which (a) received no aversive conditioning, (b) were autoshaped to a stimulus which had previously predicted shock, (c) received the aversive conditioning, and (4) were exposed to various stimuli but received no aversive reinforcement. The principal finding was that preexposure to strong shock resulted in delays in response acquisition during subsequent autoshaping. This suggests that the learned helplessness hypothesis obtains with classically conditioned responding. Additionally, the importance of shock-alone control groups in the study of transfer effects is critical. Due to the lack of statistical power, the study was not definitive regarding the nature of safety signals or appetitive-to-appetitive transfers. Statistically significant differences were only found on acquisition measures, and no such differences were found on performance measures.

A series of five experiments was conducted to determine whether operant or respondent factors controlled the emission of a particular vocalization ( "Q" ) by human infants 16 to 18 months old. Experiment 1 consisted of a pilot investigation of the effects of an autoshaping procedure on three infants' vocal behavior. All three subjects demonstrated increased emission of the target sound during the CR period. Experiments 2 through 4 attempted to replicate the findings of Experiment 1 under controlled conditions, and failed to do so. Experiment 5a presented infant subjects with a discrete-trial operant procedure (having the identical temporal parameters as the autoshaping procedure used in Experiments 1 through 4) , during which subjects received rewards only after emitting the target sound. All three experimentally naive subjects in this condition emitted the target sounds, and each met an acquisition criterion of 15 successive trials with at least one target response (CR) per trial. Subjects in Experiment 5b were exposed to the autoshaping procedure employed in Experiments 1 through 4; in addition, they were rewarded verbally for emitting the target sound at any time during the session. One of these three subjects increased her rate of target sound emission, but never met the acquisition criterion. The results suggest that vocalizations of subjects in this age range are susceptible to response-reinforcer (operant) manipulations and not to stimulus-stimulus (Pavlovian) associations. This conclusion differs from the findings of previous investigations that used younger infant subjects, suggesting that subject age may be important when conditioning vocalizations. Further research is also recommended to determine the utility of employing autoshaping procedures with humans.

Diss. Ph.D.--Anthropology--Berkeley (Calif.)--University of California, 1995. / Bibliogr. p. 141-159.

<p>Validerat; 20101217 (root)</p>