Journal of Experimental Psychology-Animal Learning and Cognition最新文献

The most common associative explanation of interference is based on a retrieval failure. Retrieval, in turn, is considered as the result of an associative activation mechanism that is thought to be fast and automatic. However, up-to-date, there is no evidence of interference based on dependent measures specifically related to this kind of low level processes. The objective of the present study was to test whether interference phenomena can be observed by using a cued response task designed to detect low level retrieval processes. Experiment 1 evaluated whether the cued response task served to show a priming effect. Such effect allowed us to interpret the results found in the remaining experiments of the series. Experiment 2 aimed to find the interference effect by using the cued response task. Experiments 3 and 4 were conducted to assess whether spontaneous recovery and context-change effects could also be observed. The results showed that interference and recovery from interference phenomena can be attributable to fast retrieval processes, which is consistent with associative accounts of interference.

Four appetitive conditioning experiments studied generalization between compound conditional stimuli (AB) and their elements (e.g., A or B). In Experiments 1 and 2, rats received conditioning with A and AB, and then extinction with either A or AB. During subsequent testing, there was more generalization of extinction (nonresponding) from the compound (AB) to the element (A) than from the element (A) to the compound (AB). This asymmetry was consistent with earlier results involving temporal discrimination learning in which short and long temporal intervals played the roles of A and AB. In Experiment 3, rats received conditioning with either A or AB, and then testing with A and AB. Consistent with elemental models of conditioning, there was more generalization of conditioned responding from A to AB than from AB to A. Experiment 4 found that these asymmetries in the generalization of extinction (Experiments 1 and 2) and conditioning (Experiment 3) both contribute to the feature-positive effect. Overall, the parallel between the current findings and previous results with temporal discrimination learning supports an associative analysis of interval timing. Implications for elemental and configural theories of conditioning and generalization are also discussed.

In Experiment 1, four groups of male rats were subjected to Pavlovian conditioning of an approach response. In one group the reinforcer was one mount with a sexually receptive female and in another group it was one intromission. A third group was deprived of food for 8 h before every session and a fourth group was deprived for 16 h. These latter groups received a 94 mg food pellet as reinforcement. The conditional stimulus (CS)+ and CS- were different lights. Rats reinforced with mount, intromission, or food after 16 h of deprivation learned to approach the CS+ more than the CS-. There was no difference in performance between the groups making one mount and one intromission. Rats deprived of food for 8 h failed to discriminate between the CS+ and the CS-. The results obtained with food reinforcement show that performance in the conditioning procedure depends on the level of motivation, which should be the case in any valid procedure. In Experiment 2 we determined whether access to female odor, exposure to an inaccessible female, one mount, and one intromission could reinforce classical conditioning. Only mount and intromission were efficient. These data show that the earliest event in the sequence of sexual behaviors that can promote conditioning is mounting. The fact that mount and intromission are equally efficient for reinforcing Pavlovian conditioning shows that the somatic and visceral responses associated with these behavior patterns rather than sensory feedback from the genitals are crucial.

If Ben is taller than Emily and Emily is taller than Dina, one can infer that Ben is taller than Dina. This process of inferring relations between stimuli based on shared relations with other stimuli is called transitive inference (TI). Many species solve TI tasks in which they learn pairs of overlapping stimulus discriminations (A+B-, B+C-, etc.) and are tested with non-adjacent novel test pairings (BD). When relations between stimuli are determined by reinforcement (A is reinforced when paired with B, B when paired with C), performance can be controlled by the associative values of individual stimuli or by logical inference. In Experiment 1 rhesus monkeys (Macaca mulatta) chose the higher ranked item on non-adjacent test trials after training on a 7-image TI task. In Experiment 2 we measured the associative values of 7 TI images and found that these values did not correlate with choice in TI tests. In Experiment 3 large experimental manipulations of the associative value of images did influence performance in some TI test pairings, but performance on other pairs was consistent with the implied order. In Experiment 4 monkeys linked two previously learned 7-item lists into one 14-item list after training with a single linking pair. Linking cannot be explained by associative values. Associative value can control choice in TI tests in at least some extreme circumstances. Implied order better explains most TI choices in monkeys, and is a more viable mechanism for TI of social dominance, which has been observed in birds and fish.

It has been shown previously that pigeons make surprising errors on a visually based midsession reversal task (Cook & Rosen, 2010; Rayburn-Reeves, Molet, & Zentall, 2011). We trained birds with red and green sidekeys, with one color rewarded in the first 40 trials (S1) and the other color rewarded in the latter 40 trials (S2). Importantly, in Phases 1 and 3, red and green were always presented on the same side, whereas in Phase 2 sidekeys were presented on the left and right equally often. In Phases 2 and 3, probe sessions with intertrial intervals (ITIs) longer or shorter than the training intertribal interval (ITI) were interjected among baseline sessions. Results showed that pigeons presented with visual-only cues used interval duration since the beginning of the session to predict when the reversal of reward contingency would occur, but pigeons presented with color and spatial dimensions confounded for predicting reward tended to use a more optimal reward-following strategy of choice based on local reinforcement.

Preexposure to intermixed presentations of a pair of similar stimuli (AX and BX, where A and B represent distinctive features, and X the features the stimuli hold in common) facilitates subsequent discrimination between them. This perceptual learning effect has been interpreted as indicating that the loss of effective salience resulting from repeated presentation of a stimulus is attenuated or reversed by a salience-modulation process that operates on the unique stimulus features A and B during intermixed preexposure. In 3 experiments, we examined discrimination after intermixed preexposure to AX and BX, making comparison with a condition in which novel unique features were added to the preexposed background (CX and DX). In all experiments, we also monitored eye gaze during both preexposure and the test. Experiments 1 and 2 found discrimination of the preexposed stimuli to be superior. This result cannot be explained by salience-modulation theories that suppose that intermixed preexposure merely attenuates loss of salience to the unique features A and B; it suggests, rather, that intermixed preexposure to AX and BX enhances the salience of, or attention paid to, the distinctive features. Experiment 3 demonstrated that exposure increases sensitivity to the spatial location of the features, a conclusion confirmed by analysis of eye gaze.

Schedule-induced drinking (SID) can occur when food-deprived rats are given access to water while receiving pellets on an intermittent reinforcement schedule. These conditions can increase water intake excessively. The possible role of adventitious reinforcement of postpellet drinking was assessed by testing whether response-reinforcer contiguity, the relative predictiveness of a response, and whether it is marked are important in the development of SID. Rats exposed to a short interpellet interval acquired SID most rapidly, with this acquired drinking response maintained when animals were transferred to a longer interpellet interval, thus indicating an easy-to-hard effect (Experiment 1). Further experiments demonstrated that a stimulus (a brief-flashing house light) occurring prior to pellet delivery could block the acquisition of SID (Experiment 2), while a lick-contingent tone, intended to increase the associability of this response, produced more rapid acquisition of SID (Experiment 3). Analysis of lick distributions revealed that licking became concentrated in the first half of an interpellet interval only after several sessions. Overall, the results indicated that similar factors affect the acquisition of both SID and instrumental conditioning with delayed reinforcement, as is consistent with a superstitious conditioning account of SID development.

In a conditioning protocol, the onset of the conditioned stimulus ([CS]) provides information about when to expect reinforcement (unconditioned stimulus [US]). There are two sources of information from the CS in a delay conditioning paradigm in which the CS-US interval is fixed. The first depends on the informativeness, the degree to which CS onset reduces the average expected time to onset of the next US. The second depends only on how precisely a subject can represent a fixed-duration interval (the temporal Weber fraction). In three experiments with mice, we tested the differential impact of these two sources of information on rate of acquisition of conditioned responding (CS-US associability). In Experiment 1, we showed that associability (the inverse of trials to acquisition) increased in proportion to informativeness. In Experiment 2, we showed that fixing the duration of the US-US interval or the CS-US interval or both had no effect on associability. In Experiment 3, we equated the increase in information produced by varying the C/T ratio with the increase produced by fixing the duration of the CS-US interval. Associability increased with increased informativeness, but, as in Experiment 2, fixing the CS-US duration had no effect on associability. These results are consistent with the view that CS-US associability depends on the increased rate of reward signaled by CS onset. The results also provide further evidence that conditioned responding is temporally controlled when it emerges.

Three experiments in rats investigated the generalization of conditioned fear from one context (B) to both a preexposed context (A) and a novel context (C). In each experiment, when the conditioning context (B) had been preexposed, there was greater generalization to context A than to context C; but when B was novel at the outset of conditioning this difference between A and C was not observed. The implications of these results for associative treatments of the development of contextual memories are evaluated.

A model proposing error-driven learning of associations between representations of stimulus properties and responses can account for many findings in the literature on object categorization by nonhuman animals. Furthermore, the model generates predictions that have been confirmed in both pigeons and people, suggesting that these learning processes are widespread across distantly related species. The present work reports evidence of a category-overshadowing effect in pigeons' categorization of natural objects, a novel behavioral phenomenon predicted by the model. Object categorization learning was impaired when a second category of objects provided redundant information about correct responses. The same impairment was not observed when single objects provided redundant information, but the category to which they belonged was uninformative, suggesting that this effect is different from simple overshadowing, arising from competition among stimulus categories rather than individual stimuli during learning.