Conditioning insulin effects.

It has previously been demonstrated that after a number of insulin injections in rats, an injection of a placebo leads to an elevation in blood sugar. It has been suggested that this apparent conditioned compensatory response is an artifact resulting from stressing the subject (when large doses of insulin are used) or represents a nonassociative phenomenon (when small doses of insulin are used). These two suggestions were rejected on the basis of the results of Experiments 1 and 2, respectively. Experiments 3 and 4 demonstrated that although the behavioral effects of insulin can be conditioned to the injection procedure, such conditioned insulinlike behaviors (contrary to suggestions of many investigators) are not mediated by a pypoglycemic state.     

Heart rate changes accompanying jaw movement Pavlovian conditioning in rabbits: Concomitant blood pressure adjustments and effects of peripheral autonomic blockade

Two experiments were conducted to ascertain the cardiovascular accompaniments of differential Pavlovian jaw movement (JM) conditioning. The first examined the blood pressure (BP) changes that accompany the tachycardiac conditioned responses (CRs) associated with JM conditioning. The BP response in all instances consisted of a depressor response that was greater to the reinforced CS+ than CS-, although the magnitude of the CR was quite small. The second experiment determined the effects of peripheral autonomic antagonists on the cardiac accelerations associated with JM conditioning. It was found that the peripheral vagal antagonist methyl scopolamine completely abolished responses to both CS+ and CS-, whereas atenolol, a beta adrenergic antagonist, augmented the response, compared to saline control injections. The JM responses were also affected by the autonomic blockades, with minimal responding occurring in the scopolamine group but slightly more JM CRs in the atenolol group, compared to saline control animals. These results suggest that the major cardiovascular response to an appetitive stimulus, which evokes JM conditioning, consists of cardiac accelerations with the BP depressor responses playing a minimal, if any, role. Moreover, these conditioned cardiac increases appear to be due solely to the release of vagal inhibition.     

Heart Rate Changes Accompanying Jaw Movement Pavlovian Conditioning in Rabbits: Concomitant Blood Pressure Adjustments and Effects of Peripheral Autonomic Blockade

Two experiments were conducted to ascertain the cardiovascular accompaniments of differential Pavlovian jaw movement (JM) conditioning. The first examined the blood pressure (BP) changes that accompany the tachycardiac conditioned responses (CRs) associated with JM conditioning. The BP response in all instances consisted of a depressor response that was greater to the reinforced CS+ than CS-, although the magnitude of the CR was quite small. The second experiment determined the effects of peripheral autonomic antagonists on the cardiac accelerations associated with JM conditioning. It was found that the peripheral vagal antagonist methyl scopolamine completely abolished responses to both CS+ and CS-, whereas atenolol, a beta adrenergic antagonist, augmented the response, compared to saline control injections. The JM responses were also affected by the autonomic blockades, with minimal responding occurring in the scopolamine group but slightly more JM CRs in the atenolol group, compared to saline control animals. These results suggest that the major cardiovascular response to an appetitive stimulus, which evokes JM conditioning, consists of cardiac accelerations with the BP depressor responses playing a minimal, if any, role. Moreover, these conditioned cardiac increases appear to be due solely to the release of vagal inhibition.     

Elimination of behavior of mental patients by response-produced extinction

Mental hospital patients were conditioned to respond at a high rate. Then an attempt was made to eliminate the response by means of a mild punishment consisting of a period of timeout from reinforcement (response-produced extinction). When only one response was available for obtaining the reinforcement, the mild punishment was not effective in eliminating that response. When an alternative response was also made available for obtaining the reinforcement, the mild punishment was completely effective. It appears that even very mild punishment may be effective if the over-all frequency of reinforcement can be maintained by means of an alternative unpunished response.     

Varying temporal location of a conditioned stimulus in heart rate conditioning ofMacaca mulatta

The several functions that a stimulus can assume were investigated in a Pavlovian conditioning procedure. The subjects were six rhesus monkeys; the response under observation was heart rate. The conditioning began with a temporal separation of zero between a signal and a regularly repeating electric shock; the signal was then moved to a series of earlier locations in the inter-shock interval. After six sessions at each location, two sessions followed in which only the shock was delivered periodically. The findings included: (1) A two-phased conditioned cardiac rate response seen at the first location became more multiphasic and irregular during longer intervals between signal and shock; (2) the location where the conditioned response peaked became increasingly variable as the signal was moved back, but this variability maintained a constant proportion to the signal-shock interval; and, (3) heart rate during a presignal period, and during a comparable period in shock only sessions, was generally deceleratory early in training and acceleratory thereafter. Sessions with the signal showed heart rate in the presignal period to have become acceleratory earlier in training than sessions with shock only. The data pertain to stimulus control over heart rate as a function of: (A) the temporal proximity of a signal to an aversive stimulus; and, (B) the presence or absence of the signal. The use of appropriate response units in cardiac conditioning is also discussed.     

Conditioned activity and the interaction of amphetamine experience with morphine's activity effects

This experiment assessed the transfer effect of Pavlovian conditioning with d-amphetamine sulfate (1 mg/kg) on morphine's activity effects. Prior experience with amphetamine resulted in higher levels of activity when challenged with morphine (10 and 20 mg/kg). This interactive effect of amphetamine, however, was present only in those animals who had experienced amphetamine paired with the activity test situation. Animals who had received equivalent doses of amphetamine unpaired with the testing environment did not differ from drug-naive control animals. Analysis of predrug activity levels revealed a conditioned activity response in paired animals compared to the controls. These findings suggest that the response interaction between drug conditioned responses and drug unconditioned responses is an important determinant of cross-drug effects between drugs of different pharmacological classes.     

Avoidance extinction in goldfish

Independent groups of goldfish trained to avoid shock in a shuttlebox situation were presented with several extinction procedures in which the relationships between the conditioned stimulus and shock were altered and/or response contingencies removed. Random shock presentations, equivalent to the number of shocks received during avoidance acquisition, resulted in response decrements similar to those obtained when the conditioned stimulus was presented alone. Pairing the conditioned stimulus with shock on every trial, however, served to maintain response levels. When response-contingent punishment was superimposed upon these Pavlovian pairings, performance was facilitated slightly although punishment alone resulted in somewhat faster response reduction than that produced by exposure only to the conditioned stimulus. Extinction of avoidance responding produced by exposure to the conditioned stimulus alone was dependent on the total duration of exposure and independent of both number of stimulus onsets and response prevention. These experiments demonstrated that, in general, the procedures used to reduce avoidance responding in rats were equally effective for goldfish, with one exception: the introduction of a Pavlovian contingency following avoidance acquisition, making the previously avoidable shock unavoidable, maintained response probabilities near previously established levels.     

Cardiac conditioning and extinction inMacaca mulatta during block of the CR by cardiac pacing

Previous work has shown that behavior acquisition within the Pavlovian paradigm occurs in the absence of responding,i.e., when conditional and unconditional responses are blocked during training. The parallel question of extinction under response blocking has received less attention. The experiments reported here find that a cardiac CR can be conditioned and extinguished even when rate changes are prevented by cardiac pacing during acquisition and extinction procedures. This finding suggests that the cardiac CR is established independently of peripheral innervations, and that “feedback” from the changing response is not necessary for Pavlovian learning of this sort to occur.     

Autoshaping the pigeon's gape response: acquisition and topography as a function of reinforcer type and magnitude.

The pigeon's key-pecking response is experimentally dissociable into transport (head movement) and gape (jaw movement) components. During conditioning of the key-pecking response, both components come under the control of the conditioned stimulus. To study the acquisition of gape conditioned responses and to clarify the contribution of unconditioned stimulus (reinforcer) variables to the form of the response, gape and key-contact responses were recorded during an autoshaping procedure and reinforcer properties were systematically varied. One group of 8 pigeons was food deprived and subgroups of 2 birds each were exposed to four different pellet sizes as reinforcers, each reinforcer signaled by a keylight conditioned stimulus. A second group was water deprived and received water reinforcers paired with the conditioned stimulus. Water- or food-deprived control groups received appropriate water or food reinforcers that were randomly delivered with respect to the keylight stimulus. Acquisition of the conditioned gape response frequently preceded key-contact responses, and gape conditioned responses were generally elicited at higher rates than were key contacts. The form of the conditioned gape was similar to, but not identical with, the form of the unconditioned gape. The gape component is a critical topographical feature of the conditioned key peck, a sensitive measure of conditioning during autoshaping, and an important source of the observed similarities in the form of conditioned and consummatory responses.     

Stimulus specificity in avoidance learning

The present experiments address the issue of stimulus specificity in fear and avoidance learning. First, it was established that light stimuli are effective warning signals (WS) in shuttle avoidance. Then light stimuli were shown to produce conditioned suppression in the conditioned emotional response situation comparable to that produced by noise conditioned stimuli. Finally, the effectiveness of noise onset and noise offset as feedback signals was tested. This was assessed under conditions of immediate and delayed termination of a light WS. Delayed termination of a light WS interfered with avoidance learning and the introduction of noise offset as a feedback signal enhanced it. The only demonstration of stimulus specificity was the failure of noise onset to function as a feedback signal.     

Free-operant escape-avoidance of noise by rats

A series of experiments was conducted to establish free-operant escape-avoidance responding in rats using noise as the stimulus. Naive rats did not acquire a bar-press response on an escape-avoidance of noise schedule. Similarly, free-operant responding established using escape-avoidance of shock was not maintained when noise was substituted for shock. Noise stimuli of 110 dB did maintain responding, but at a lower level than during training, when the noise stimuli had first been paired with shock. Noise stimuli of 97 dB and 87 dB were not effective under those same conditions. Additional rats were trained on a free-operant escape-avoidance schedule of shock and then exposed to a delayed conditioning procedure in which noise was the conditioned stimulus and shock was the unconditioned stimulus. When these subjects were then tested with noise alone, two of the three subjects conditioned and tested with 105-dB noise displayed escape-avoidance of noise, but none of the rats conditioned and tested at 97 dB displayed escape-avoidance of noise. The results suggest that free-operant escape-avoidance of noise can be demonstrated; however, only higher intensity noise stimuli that have been paired with shock are effective.     

Instrumental conditioning of aggressive behavior in rats

A method has been developed for bringing an aggressive response under stimulus control. It was found that the number of conditioned aggyessive responses was maximal when low-weight target rats were used. The latencies of the conditioned responses toward target animals of 124 gm were significantly lower than those toward animals of 221 and 284 gm. The application of an extinction procedure on the conditioned aggressive response substantially increased the total number of emitted aggressive responses.     

Pavlovian conditioning of shock-elicited aggression: a discrimination procedure

Two auditory stimuli, separated by a fixed intertrial interval, were alternately presented to two rats in a closed environment. The positive conditioned stimulus (CS+) terminated with the offset of a 2-mA, 0.75-sec shock. The negative conditioned stimulus (CS-) terminated without shock. The incidence of the "stereotyped fighting posture" was recorded during the CS+, the CS-, the intertrial interval, and shock. The results showed an increase in the percentage of conditioned responses during the CS+, and a decrease during both the CS- and the intertrial interval, when the duration of the conditioned stimuli and the intertrial interval was 16 sec. Appropriate changes in the incidence of aggression during the two stimuli were obtained following the reversal of the stimulus functions. During the acquisition and reversal phases there was a between-session decrement and a within-session improvement in the incidence of aggression during the CS+, defined as warm-up. The presentation of free shocks before the conditioning sessions was effective in reducing the warm-up only when the interval between shocks was 64 sec. These data were interpreted as demonstrating classical conditioning of shock-elicited aggression, with little chance of non-associative factors contributing to the measurement of the conditioned response.     

Effectiveness of the counterconditioning procedure in eliminating avoidance behavior

Data were obtained on the effectiveness of three forms of counterconditioning—each differing in the degree to which competing responses were introduced. Counterconditioning was also compared with an extinction procedure in eliminating an instrumental avoidance response. Only the counterconditioning procedure which evoked and reinforced another conditioned response during extinction of the avoidance response, was significantly more effective than a traditional extinction procedure in achieving a decrement in avoidance responding and this was only on the first session on which such procedures were in effect. When the opportunity to perform the competing response was removed, only Ss in this group evidenced a significant increase in avoidance responding.

All procedures were equally effective over sessions in eliminating avoidance behavior. A delay in effectiveness occurred to the degree to which a procedure introduced a competing response. It was in terms of the immediacy of response reduction and achievement of a very low rate of responding with very few responses being performed, that the counterconditioning procedure was superior to the extinction procedure.

The implication of these results for behavior theory and therapy were elaborated.     

Effects of noun imagery and awareness of the discriminative cue upon differential eyelid conditioning to grammatical and ungrammatical phrases

Two differential eyelid conditioning studies employed grammatically correct and incorrect adjective-noun phrases as conditioned stimuli. For different groups of subjects, the nouns were either high or low in imagery. The hypothesis that congruency between grammatical correctness and reinforcement consequences (i.e., the aversive stimulus contingent upon presence of incorrect rather than correct grammar) would facilitate conditioned discrimination was not supported, but the hypothesis that high noun imagery would facilitate differential response to syntax received strong support. Cognitive awareness of the syntactic discriminandum was also related to effective differential responding, as well as being implicated as a mediating mechanism in the imagery effects. Finally, performance was also significantly related to conditioned-response topography, with better conditioned discrimination by voluntary-form (V) than by conditioned-form (C) responders, and also evidence of more effective utilization of contingency awareness by Vs than by Cs.     

The Topography of Sexually Conditioned Behaviour: Effects of a Trace Interval

In a trace conditioning procedure, subjects were presented with a 30-sec conditioned stimulus (CS) followed by a 30-sec trace interval. Delayed conditioning consisted of a 60-sec CS presentation followed by an unconditioned stimulus (US). Although conditioning developed with both procedures, the topography of the conditioned response differed. Sexual conditioned approach was evident in all of the subjects during the presentation of the CS. Traceconditioned subjects moved away from the area where the CS had been presented during the trace interval but remained closer to the CS location than did an unpaired control. This reduction in the spatial specificity of the conditioned response was interpreted from a behaviour systems perspective. The trace interval presumably increased the perceived separation between the CS and the US and therefore elicited conditioned behaviour less specifically directed towards the CS.     

Effects of d-amphetamine on responding under second-order schedules of reinforcement with paired and nonpaired brief stimuli.

Three pigeons were studied under a multiple schedule in which pecks in each component were reinforced according to a variable-interval 120-s second-order schedule with fixed-interval 60-s units. In the first component of the multiple schedule, the completion of a fixed interval produced either food or a 4-s change in key color plus houselight illumination. In the second component an identical schedule was in effect, but the stimulus was a 0.3-s change in key color. Both long and short brief stimuli were not paired with food presentations in Conditions 1 and 3 and were paired with food in Condition 2. There were no consistent differences in response patterns under paired and nonpaired brief-stimulus conditions when the stimulus was a 4-s change in key color accompanied by houselight illumination. However, pairing the 0.3-s key-color change with food presentations resulted in higher indices of curvature and lower response rates in the early segments of the fixed interval than when the stimulus was not paired with food presentations. Low doses of d-amphetamine (0.3 and 1 mg/kg) produced small and inconsistent increases in overall response rates, and higher doses (3 and 10 mg/kg) decreased overall response rates. d-Amphetamine altered response patterns within fixed intervals by decreasing the indices of curvature and increasing response rates in the early segments of the fixed interval. Response rates and patterns under paired and nonpaired brief-stimulus conditions were not differentially affected by d-amphetamine. Thus, evidence for the enhancement of the conditioned reinforcement effects of psychomotor stimulant drugs was not found with the second-order schedules used in the present study.     

The comparator hypothesis of conditioned response generation: manifest conditioned excitation and inhibition as a function of relative excitatory strengths of CS and conditioning context at the time of testing

In the present research water-deprived rats were used in a conditioned lick suppression paradigm to test and further develop Rescorla's (1968) contingency theory, which posits that excitatory associations are formed when a conditioned stimulus (CS) signals an increase in unconditioned stimulus (US) likelihood and that inhibitory associations develop when the CS signals a decrease in US likelihood. In Experiment 1 we found that responding to a CS varied inversely with the associative status of the context in which the CS was trained and that this response was unaltered when testing occurred in a distinctively dissimilar context with a different conditioning history, provided associative summation with the test context was minimized. These results suggest that manifest excitatory and inhibitory conditioned responding is modulated by the associative value of the training context rather than that of the test context. In Experiment 2 it was demonstrated that postconditioning decreases in the associative value of the CS training context reduced the effective inhibitory value of the CS even when testing occurred outside of the training context. Moreover, this contextual deflation effect was specific to the CS training context as opposed to any other excitatory context. Collectively, these studies support the comparator hypothesis, which states that conditioned responding is determined by a comparison of the associative strengths of the CS and its training context that occurs at the time of testing rather than at the time of conditioning. This implies that all associations are excitatory and that responding indicative of conditioned inhibition reflects a CS-US association that is below (or near) the associative strength of its comparator stimulus. It is suggested that response rules which go beyond a monotonic relation between associative value and response strength can partially relieve learning theories of their explanatory burdens, thereby allowing for simpler models of acquisition.     

Cortical barrel lesions impair whisker-CS trace eyeblink conditioning

Whisker deflection is an effective conditioned stimulus (CS) for trace eyeblink conditioning that has been shown to induce a learning-specific expansion of whisker-related cortical barrels, suggesting that memory storage for an aspect of the trace association resides in barrel cortex. To examine the role of the barrel cortex in acquisition and retrieval of trace eyeblink associations, the barrel cortex was lesioned either prior to (acquisition group) or following (retention group) trace conditioning. The acquisition lesion group was unable to acquire the trace conditioned response, suggesting that the whisker barrel cortex is vital for learning trace eyeblink conditioning with whisker deflection as the CS. The retention lesion group exhibited a significant reduction in expression of the previously acquired conditioned response, suggesting that an aspect of the trace association may reside in barrel cortex. These results demonstrate that the barrel cortex is important for both acquisition and retention of whisker trace eyeblink conditioning. Furthermore, these results, along with prior anatomical whisker barrel analyses suggest that the barrel cortex is a site for long-term storage of whisker trace eyeblink associations.     

Pavlovian conditioning of sexual arousal: parametric and background manipulations

Recent studies have shown that a Pavlovian conditioned stimulus (CS) for unconsummated sexual arousal can increase the rate of copulation in the rat. This report includes five experiments examining the effects of parametric manipulations on the conditioned arousal response. Results show that between six and nine trials are necessary for reliable conditioning, but extinction is somewhat slower than acquisition. The function for the CS-US (unconditioned stimulus) interval is quadratic, with a minimum of several minutes required for effective conditioning. In the first three experiments, it appeared that background cues were conditioned as well as the designated CSs, and this was tested explicitly in the last two studies. In one, the effect of background cues was shown by training and testing in different situations; in the second, background cues were shown to be subject to latent inhibition. These results demonstrate the influence of Pavlovian learning in sexual behavior and help to provide the basis for an animal model of the acquisition of deviant sexual arousal in humans.