Perceptual learning transfer in an appetitive Pavlovian task

In two experiments, rats were given intermixed or blocked preexposure to two similar compound stimuli, AX and BX. Following preexposure, conditioning trials took place in which AX (Experiment 1) or a novel compound stimulus NX (Experiment 2) was paired with a food-unconditioned stimulus in an appetitive Pavlovian preparation. Animals that were given alternated preexposure showed lower generalization from AX to BX (Experiment 1) and from NX to a new compound, ZX (Experiment 2), than animals that were given blocked preexposure, a perceptual learning and a perceptual learning transfer effect, respectively.     

Overexpectation in appetitive Pavlovian and instrumental conditioning

In three experiments that used appetitive preparations with rats, we examined the effects of reinforcing a compound consisting of two previously reinforced stimuli on subsequent responding to those stimuli. Experiment 1 showed that a Pavlovian conditioned stimulus given this treatment evoked fewer magazine entries when presented alone than did a reinforced stimulus that did not receive the compound treatment. Experiment 2 examined inhibition of delay and generalization decrement accounts for the results of Experiment 1. Experiment 3 extended this finding to an instrumental learning paradigm.     

Pavlovian appetitive conditioning under curare in rats

A CS was paired with rewarding intracranial stimulation while Ss were immobilized by curare. Tests of the activity response to the CS were carried out before and after conditioning. With either simple or discriminative conditioning, activity to the rewarded CS increased after training. These results are comparable to those in studies using food reward and support the hypothesis that a central motivational state is conditioned to stimuli preceding reward.     

Contextual effects in latent inhibition with an appetitive conditioning procedure

In three experiments, rats received presentations of a diffuse 30-sec stimulus (a light) and of food, and their tendency to enter the food tray was monitored. Experiment 1 showed that when the light was made to signal the delivery of food, the response of entering the food tray increased in frequency during the stimulus. The acquisition of this conditioned response to the light was retarded in subjects that had received preexposure to the stimulus. In Experiments 2 and 3, subjects received preexposure to the stimulus, some in the same context as that subsequently used for stimulus-food pairings and some in a different context. Those experiencing the change of context acquired the response more readily. It is argued that these results demonstrate a latent inhibition effect that is attenuated by contextual change.     

Memory priming and trial spacing effects in Pavlovian learning

Conditioning trials that are massed in time produce less conditioning than those that are spaced in time. Four experiments with rat subjects examined whether a recent conditioning trial interferes with conditioning on the next trial by temporarily “priming” information in short-term memory (e.g., Wagner, 1978, 1981). We used appetitive conditioning procedures in which priming trials preceded target trials by 60 sec. When the priming trials were nonreinforced presentations of a conditioned stimulus (CS), the CS had to be the same CS as the one on the target trial to interfere with conditioning. When priming trials were actual CS-unconditioned stimulus (US) pairings, the CS identity did not matter; the US was the event that interfered with conditioning on the next trial. Reinforced trials reduced performance in a way that did not depend on context blocking. The results suggest that CS and US priming effects do contribute to conditioning deficits observed with massed trial procedures. The results are consistent with Wagner’s (1981) “sometimes opponent process,” or SOP, model, although a result that is paradoxical for the model suggests that recent USs may have motivational as well as memory effects.     

Temporal determinants of occasion setting in feature-positive discriminations

Three experiments examined the acquisition and transfer of Pavlovian feature-positive discriminations (XA+, A?) in rat subjects. To identify the nature of the associations formed in those discriminations, the form of the conditioned responses (CRs) was examined. If the feature,X, and common element, A, cues started and ended together onXA compoud trials, associations betweenX and the food unconditioned stimulus (US) were acquired. If the onsets and/or terminations ofX preceded those of A,X acquired the ability to set the occasion for responding to A, that is, A evoked CRs only onXA compound trials. The acquisition of occasion setting was favored when (1) the onset of X preceded that of A, (2) the interval betweenX and A and/or the US was relatively long, and (3) the termination ofX occurred prior to the onset of A. The occasion-setting power ofX was fairly specific to A:X did not modulate responding evoked by another cue that had been first trained and then extinguished or by a cue that had been paired with the US only a few times. However,X did enhance responding to a cue that had been a common element in another, identical feature-positive discrimination. That transfer was somewhat greater if theX and A terminated together than ifX terminated prior to the onset of A. Implications for theories of stimulus control in Pavlovian conditioning are discussed.     

The effects of qualitative and quantitative variation in the US on individual components of Pavlovian appetitive conditioned behavior in rats

The form of rats’ Pavlovian conditioned responses to visual and auditory conditioned stimuli (CSs) paired with a variety of unconditioned stimuli (USs) was examined in three experiments using direct behavioral observation techniques. In Experiment 1, the form of conditioned behavior occurring most frequently during later portions of the CS-US interval depended only on which of several appetitive USs was used, but the form of behavior occurring most frequently during early portions of the CS-US interval depended only on the nature of the CS. US-dependent behaviors resembled the response to the US, and CS-dependent behaviors resembled the original orienting response (OR) to the CS. In Experiment 2, the use of larger magnitude appetitive USs resulted in higher frequencies of US-dependent behaviors, but lower frequencies of CS-dependent behaviors in the presence of auditory and visual CSs. In Experiment 3, US-dependent conditioned behavior to auditory and visual CSs paired with shock was more frequent when high-intensity shocks were used, but CS-dependent behavior was more frequent when low-intensity shocks were used. These results suggested that Pavlovian conditioned responding may involve two independent types of behavior—one appropriate to the US and another based on the original OR to the CS.     

Learned helplessness in an appetitive discrete-trial T-maze discrimination test

Four groups of rats were exposed to response-contingent, yoked noncontingent, or en masse food deliveries in a Skinner box or to no experimental pretreatment. All groups were subsequently tested for transfer of the learned-helplessness effect to an appetitive discrete-trial T-maze discrimination employing experimenter-blind procedures. The yoked group showed retarded discrimination learning in comparison with the response-contingent and naive control groups but not in comparison with the en masse control group. This nonsignificant difference between the yoked group and the en masse group may reflect the effect of limited exposure to uncontrollability in the en masse group. The groups did not differ in terms of the speed of maze traversal. The latter result suggests that the learned-helplessness effect observed in discrimination was not due to a competing response.     

Transient variations in responding to Pavlovian conditioned stimuli have implications for the mechanisms of “priming”

Conditioned responding to a well-trained conditioned stimulus (CS) was assessed in an eyelid conditioning situation under three conditions of prior stimulation: when preceded by recent presentation of the same CS, when preceded by recent presentation of a different CS, and when preceded by no recent stimulation. As compared to the latter condition, prior presentation of the same CS depressed responding, while prior presentation of a different CS augmented responding. Both effects diminished as the interval separating the test stimulus from the preceding CS was lengthened over the range of 2.5 to 10 sec. The results were discussed in terms of the interaction of short-term memory representations with subsequent stimulation, and a specific theory concerning the effects of “priming.”     

Context effects on conditioning,extinction, and reinstatement in an appetitive conditioning preparation

Three experiments with rat subjects examined the effects of contextual stimuli on performance in appetitive conditioning. A 10-sec tone conditioned stimulus (CS) was paired with a food-pellet unconditioned stimulus (US); conditioning was indexed by the observation of headjerking, a response of the rat to auditory stimuli associated with food. In Experiment 1, a context switch following initial conditioning did not affect conditioned responding to the tone; however, when the response was extinguished in the different context, a return to the original conditioning context “renewed” extinguished responding. These results were replicated in Experiments 2 and 3 after equating exposure to the two contexts (Experiment 2) and massing the conditioning and extinction trials (Experiment 3). The results of Experiment 1 also demonstrated that separate exposure to the US following extinction reinstates extinguished responding to the tone; this effect was further shown to depend at least partly on presenting the US in the context in which testing is to occur (Experiments 2 and 3). Overall, the results are consistent with previous data from aversive conditioning procedures. In either appetitive or aversive conditioning, the context may be especially important in affecting performance after extinction.     

Signaling and affective functions in Pavlovian conditioning

The present study employed a Pavlovian-instrumental-transfer paradigm to investigate the role of conditioned fear in appetitive discrimination learning. Each of three Pavlovian training procedures was used to establish a conditioned fear excitor (CS+), a “neutral” CS (CSo), and a conditioned fear inhibitor (CS?). Then, the CSs were administered to rats in the three groups contingent upon the rewarded response in a difficult visual discrimination. In addition, half of each group received shock punishment for each incorrect response. Relative to CSo, CS+ facilitated performance in contrast to the usual interfering effect of conditioned suppressors; conversely, CS? retarded performance even when its reinforcing action (fear inhibition) was potentiated by punishment for the incorrect response. These results, together with other findings showing a reversed outcome when the CSs are administered for the incorrect response, indicate that Pavlovian conditioning comprises both general signaling and affective functions, the former reflecting a basic “expectancy” or nominal type of cognitive processing in the rat.     

Trial and intertrial durations in appetitive conditioning in rats

The effects of trial (T) and intertrial (I) durations were examined in two Pavlovian conditioning experiments with rats, in which a noise conditioned stimulus (CS) was paired with food delivery. In Experiment 1,T was either 10 or 20 sec, andI ranged from 15 to 960 sec, in separate groups of rats. The acquisition rate and final level of conditioned responding showed ratio invariance: They were better predicted by theI/T ratio than byI orT alone. In Experiment 2, theI/T ratio was 6.0 in all the groups, andT was 20, 40, 80, or 160 sec. Ratio invariance was not observed: Despite the commonI/T ratio, the rate of acquisition, final level of conditioned responding, and the ability of the CS to block conditioning of another stimulus differed among the groups. At the same time, the temporal distribution of conditioned responding withinT was similar in all the groups throughout conditioning and extinction and showed superpositioning when normalized acrossT. Many but not all aspects of the data were consistent with scalar timing theory.     

Inescapable shock interferes with the acquisition of a low-activity response in an appetitive context

This study investigates the effects of exposure to inescapable shock on the acquisition of a low-activity appetitive response using a trial procedure. Inescapable shock was found to interfere with the acquisition of a nose-poke response to obtain food as compared with animals exposed to either escapable shock or no shock. In addition, general activity levels were measured separately during the trial and the intertrial interval during the appetitive test. Inescapably shocked animals were less active during the trial component than were either the escapably shocked or the nonshocked animals. However, no differential levels of activity were observed during the intertriai interval component of the appetitive test. The relevance of these findings for both the learned helplessness and the learned inactivity hypotheses is discussed.     

Evidence for the interchangeability of an avoidance behavior and a negative occasion setter

Recent research on avoidance behavior provided evidence that such behavior can function as a negative occasion setter. We tested this hypothesis further by investigating whether the modulatory function of a stimulus occasion setter transfers selectively to a relation previously modulated by an avoidance behavior, and whether the modulatory function of an avoidance behavior transfers selectively to a relation previously modulated by a stimulus occasion setter. The three experiments reported in this article provided evidence to support this hypothesis. Furthermore, the results of Experiment 1 suggested that the presence of counterconditioning trials is not a necessary condition for an avoidance behavior to function as a negative occasion setter. All three reported experiments support the occasionsetting account of avoidance behavior.     

The organization and temporal properties of appetitive behavior in rats

In the presence and absence of an externalinterfood clock stimulus (a sequence of flashing lights), rats showed a multimodal behavior pattern during successive quarters of interfood intervals (IFI) ranging from 12 to 192 sec. Responses near the feeder peaked before and just after food presentations, whereas locomotion remote from the feeder peaked toward the middle of the IFI. The temporal patterns of nosing in the feeder and remote locomotion were scalar (the time at which a response peaked in the IFI was proportional to the IFI length), whereas the patterns of postfood feeder-directed behavior, rearing, and pawgrooming were time bound (peaking at a fixed time after food, regardless of IFI length). Responses varied in their control by the external clock stimulus. During the last half of the IFI, rats nosed in the feeder more with an external clock, but only at intermediate IFIs. During the first quarter of the IFI, rats pawgroomed more with an external clock, but only at the longest IFI. The general sequence of responses during the interfood clock was consistent with the view that food delivery engages an organized sequence of search states that are expressed through a variety of responses.     

The overshadowing of background stimuli by an informative CS in aversive Pavlovian conditioning with rats

Two experiments investigated the capacity of a nominal CS to overshadow background stimuli. Rats received CS-shock pairings in one compartment of a double-compartment apparatus. After training, the shock compartment was re-presented but in the absence of both the CS and shock, and overshadowing was assessed by measuring the rats’ latency to enter the compartment. In the first experiment, predictive values of temporal cues provided by CS onset and CS offset were manipulated. Rats readily entered the shock compartment, provided shock onset had previously been predicted by CS onset or CS offset. This indicates that background cues in the shock compartment had acquired little associative strength during training. In contrast, rats avoided the shock compartment under every condition in which shock onset had not previously been predicted by either CS onset or CS offset. In the second experiment, a precise temporal cue provided by CS onset was dissociated from other factors arising from CS-shock contiguity. It was found that rats’ reactions to the shock compartment after training was governed by both temporal and contiguity factors. The results are relevant to theories which state that conditioning is a function of a competitive relationship between stimuli present in an animal’s environment during training.     

The Role of Stress and Negative Emotions in an Occupational Crisis

The study examined how negative affects and exposure to various stressors are related to an occupational crisis. Two hundred and seventy-seven employees (53% women) from various occupations filled in the Occupational Crisis Scale, a stressor questionnaire, the Anger Expression Scale (measuring both suppressed and overt anger), Spielberger's Anxiety Inventory (measuring both state and trait anxiety) and Beck's Depression Inventory. The results showed that occupational crisis was a function of work overload, interpersonal problems and frustration at work, organizational changes, a threat of job loss, and/or family worries. In addition, occupational crises were typically experienced by women and were characterized more by trait anxiety, suppressed anger and depressive symptoms than by overtly expressed anger or state anxiety. Of the three female employee groups who were most vulnerable to the crisis, the group which had suffered from interpersonal problems and frustration at work displayed the most indices of the crisis.     

Prediction of attributional consequences in an actual achievement setting

One hundred ninety-six undergraduates who received feedback on a midterm examination participated in this study. A random subgroup formed a cross-validation sample. Through the use of regression analysis, it was found that both objective and subjective performance ratings did not predict subjects' expectancy ratings but did substantially predict their ratings of pride/shame. Inclusion of attributions enhanced prediction of expectancy but not pride/shame ratings of subjects. On the basis of the findings from this study, a partial reformulation of Weiner's attributional model was proposed. In addition, numerous methodological concerns associated with attributional research were examined.