Constraints on Pavlovian aversive conditioning: Implications for avoidance learning in the rat

Four experiments investigated the relative degree of control exerted by several conditional stimuli when each stimulus: (a) preceded shock, (b) followed shock, and preceded a shock-free interval, (c) was independent of shock, or (d) was novel. When the onset of an auditory stimulus had preceded shock (Experiments 1, 2A, and 3), it always exerted conditioned excitatory control. When the same stimulus preceded a shock-free interval, it never exerted conditioned inhibitory control. When the onset of light (Experiments 2B, 4), silence (2C), or darkness (1, 2D) preceded a shock-free interval, it always exerted conditioned inhibitory control. However, when one of the latter stimuli preceded shock, it failed to exert excitatory control. Several models of this phenomenon were tested. The implications of these results for the species-specific defence reaction and two-factor theory accounts of avoidance learning were outlined.     

Interference with ingestional aversion learning produced by preexposure to the unconditioned stimulus: Associative and nonassociative aspects

Preconditioning exposure to a lithium chloride unconditioned stimulus (US) interferes with the subsequent conditioning of a taste aversion. Multiple US preexposures produce a long-lasting or durable interference with aversion learning, whereas a single US exposure produces a transient interference effect. The present experiments demonstrate that the durable US preexposure effect is substantially reduced if the method of drug treatment (infusion versus injection of the drug into the peritoneal cavity) or the spatial cues present during drug treatment (home cage versus a distinctive environment) are changed between the preexposure and taste conditioning phases of the experiment. In contrast, these manipulations do not attenuate the proximal/transient US preexposure effect. These findings indicate that different mechanisms are responsible for the two US preexposure effects. The results are consistent with previous suggestions that the durable effects of lithium preexposure are due to associative interference produced by the exteroceptive stimuli that accompany drug administrations and indicate that the proximal/transient US preexposure effect is mediated by nonassociative mechanisms.     

Sequential effects on discrimination reversal

In Experiment 1 the sequence of trials to the positive (S+) and negative (S?) discriminanda was varied between groups during acquisition and reversal of a successive brightness discrimination. In Experiments 2 and 3, groups received different reward sequences in Phase 1 within S+. In general, groups given transitions from nonrewarded trials to rewarded trials (N-R transitions) in Phase 1 learned both the original discrimination and its reversal more slowly than groups given schedules devoid of N-R transitions. The results were discussed in relation to previously reported effects of partial reinforcement on acquisition and reversal of a discrimination and the role of sequential variables and internal, reward-produced cues in discrimination learning, reversal learning, and nonreversal shifts.     

Reactions to objective self-awareness

In order to determine reactions to objective self-awareness, 96 female undergraduates received either positive or negative feedback on a “creativity” task prior to being given an opportunity to write a response to a visual cue. Half of the subjects were made objectively self-aware, via a mirror, during the visual cue task; half were not. In addition, half of the subjects were led to believe that the visual cue task was highly related to creativity, while half learned that the task was low in relevance. A “longer the response, the better” standard of correctness was established for all subjects. As predicted, the results indicated that when made objectively self-aware, subjects who received negative feedback wrote more in response to the visual cue than did those who received positive feedback, a difference which was not obtained for the subjectively self-aware subjects. The task relevance manipulation also produced a significant main effect. A similar pattern of results was obtained on a measure of the time spent on the task. The implications of the results for objective self-awareness theory are considered.     

Aphasic adults' use of heuristic and structural linguistic cues for sentence analysis

Eight aphasic adults with relatively preserved auditory comprehension and 12 normal adults were tested for their ability to analyze sentences in which the functional relations between the verb and nouns was either directly reflected by word order expectancies, or marked by a functor or non-NVN word order. The subjects' task was to designate the agent of each sentence. Results indicated that aphasics utilize word order expectancies but are impaired in their ability to exploit functors and particularly, word order markers for sentence analysis. Results are discussed in terms of aphasics' use of heuristic versus structural linguistic cues for interpreting sentences.     

Natural, unnatural, and supernatural concepts

Five experiments investigating information-processing consequences of concept naturalness and unnaturalness are reported. In particular, an attempt is made to examine the separate and joint effects of simplicity and entrenchment upon reasoning with natural and unnatural concepts. The experiments employed four variants of a concept-selection task in which subjects characterized the state of an object at some future time on the basis of information about the object at that time and at some earlier time. In all five experiments, both simplicity and entrenchment affected ease of information processing. The last two experiments showed that the effect of simplicity was greater than that of entrenchment. An informationprocessing model of task performance provided a very good account of the latency and error data. Scores from the concept-selection task correlated with scores from a set of psychometric inductive-reasoning tests; indeed, the correlations were higher than those usually found between cognitive task performance and psychometrically measured intelligence. Processing of nonentrenched concepts may provide a useful means for studying the nature of intelligent performance.