Differences in the associability of relevant and irrelevant stimuli.

Pigeons in two experiments were first trained with a set of simple discriminations of the form AX+ CX?, BY+ DY? where A, B, C, and D were relevant, and belonged to one dimension, and X and Y were irrelevant and belonged to a different dimension. They were then tested with a discrimination of the form AX+ AY? BX?. The experiments revealed that the discrimination between AX+ and BX? was acquired more readily than between AX+ and AY?, which indicates that the original training resulted in the associability of the relevant stimuli being greater than that of the irrelevant stimuli. Experiment 2 revealed that the status of other stimuli from the two dimensions influenced these changes in associability. The associability of X and Y was enhanced by making other stimuli from the same dimension relevant, and the associability of A and B was reduced by making other stimuli from the same dimension irrelevant. The associability of the stimuli is attributed to the attention they are paid. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Two kinds of attention in Pavlovian conditioning: Evidence for a hybrid model of learning.

Four appetitive Pavlovian conditioning experiments with rats examined the rate at which the discrimination between compounds AY and AX was solved relative to the discrimination between compounds AY and BY. In Experiments 1 and 2, these discriminations were preceded by training in which A and B were continuously reinforced and X and Y were partially reinforced. Consistent with the Pearce and Hall (1980) model, the results showed that the AY/AX discrimination was solved more readily than the AY/BY discrimination. In Experiments 3 and 4, the discriminations were preceded by feature-positive training in which trials with AX and BY signaled food but trials with X and Y did not. Consistent with the Mackintosh (1975) model, the results showed that the AY/BY discrimination was solved more readily than the AY/AX discrimination. These results are discussed with respect to a hybrid model of conditioning and attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential outcome effects in Pavlovian biconditional and ambiguous occasion setting tasks.

Three experiments with rats explored the differential outcome effect (DOE) using a Pavloian magazine approach conditioning preparation. Experiment 1 compared groups trained on a biconditional discrimination (AX+, AY?, BX?, BY+) with differential or nondifferential outcomes, and Experiment 2 examined this using an ambiguous occasion setting task (e.g., AX+, X?, Y+, AY?). In both experiments, subjects trained with differential outcomes learned the tasks better than subjects trained with nondifferential outcomes. Furthermore, subjects given differential outcome training learned the positive occasion setting component of the ambiguous task more efficiently than the negative occasion setting component, although both were enhanced by differential outcome training. Experiment 3 demonstrated that the ambiguous occasion setting task was reversed more readily when the target–outcome relations (as opposed to the modulator–outcome relations) were maintained during the reversal phase. These data suggest that an acquired distinctiveness effect may be responsible for the DOE in Pavlovian learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Associative changes in elements and compounds when the other is reinforced.

Four experiments investigated the symmetry of associative changes in stimulus compounds and elements in a Pavlovian conditioned magazine-approach situation with rats. Experiment 1 used multiple groups to examine the associative changes in a conditioned element (A) as a result of its subsequent reinforcement in compound with a neutral X. These were compared with the changes in an AX compound when one of its elements (A) was subsequently reinforced alone. Although reinforcing A enhanced responding to the AX compound, compared with a control compound, reinforcing AX failed to enhance responding to A, compared with a control element. Experiments 2 and 3 made similar comparisons in a fully within-subject design, finding greater changes in a previously trained AX compound when A was subsequently conditioned than in a B element when BY was subsequently conditioned. Experiment 4 found associative decrements in A when it was reinforced in the presence of a moderately conditioned X. The results observed in each of these experiments are more consistent with an elemental model of conditioning than with a recently proposed configural model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analysis of the content of configural representations: The role of associatively evoked and trace memories.

Two experiments examined the content of configural learning in rats. In Experiment 1, after simple pre-exposure to two hybrid contexts (AB and CD), rats acquired a configural discrimination involving two of the contexts (A and C) and two auditory stimuli (X and Y; AX→food, AY→no food, CX→no food, and CY→food). When rats were then placed in context B, they were more likely to respond to X than Y, and when they were placed in context D the reverse was the case. Experiment 2 demonstrated that rats can acquire a configural discrimination involving the presence of context (A) and its memory trace (a; AX→food, AY→no food, aX→no food, and aY→food). These results show that associatively provoked memories (Experiment 1) and memory traces (Experiment 2) can participate in configural discriminations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Acquisition of superexcitatory properties by an irrelevant background stimulus.

Six appetitive conditioning experiments with rats demonstrated that an irrelevant X accompanying a negative patterning discrimination (XA+, XB+, XAB-) acquires extraordinarily high levels of conditioned excitation. Responding to X was similar to that evoked by 2 excitors in combination (Experiment 1) and was greater than responding to a separately reinforced Y (Experiments 2-5). Superexcitatory properties were not acquired by X in the nonpatterning discriminations of Experiments 2-4. Experiment 5 found that A and B, if anything, were weakly excitatory. Making them more strongly excitatory after conditioning did not interfere with retention of the original discrimination (Experiment 6). Results support a counterintuitive prediction of associative theories that, under carefully arranged conditions, irrelevant stimuli may acquire superexcitatory properties. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stimulus preexposure, comparison, and changes in the associability of common stimulus features

In four experiments, rats received preexposure either to both of two compound flavours (AX and BX), or to just one (BX). Experiment 1 demonstrated a perceptual learning effect, showing that, for animals given preexposure to both flavours, an aversion conditioned to AX generalized only poorly to BX. Subsequent experiments assessed the properties of the common feature, X. Experiment 3 showed that the two preexposure treatments did not differ in the extent to which they produced habituation of the neophobia evoked by X. Experiment 2 showed that conditioning to X proceeded more rapidly in subjects given preexposure to both AX and BX than in subjects preexposed to BX alone. In Experiment 4, a similar effect was found when the elements of the compounds were presented serially. It is concluded that the perceptual learning effect of Experiment 1 occurs in spite of the fact that preexposure to two stimuli tends to maintain the associability of their common elements.     

Analysis of the unique cue in configural discriminations.

Investigated the basis of configural discriminations, using an autoshaping procedure, in 4 experiments with 68 female Carneaux pigeons. The elements of both a negative patterning (A+, B+, AB–) and a conditional discrimination (AC+, BD+, AD–, BC–) were paired in a 2nd-order procedure with 2 new key lights, X and Y. Responding was then tested to X and Y presented in compound in each other and with A and B. The pattern of responding to compounds containing X and Y was like the pattern of responding to compounds containing their associates, A and B. This suggests that A and B can be replaced by their associates without disrupting responding to their compounds. Because X and Y are physically different from A and B, this in turn suggests that any unique cue controlling responding to their compounds does not depend on the physical presence of the component stimuli. Instead the unique stimulus appears to arise from the joint activation of memory representations. (13 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inhibition and facilitation by B over C after A+, AB–, and ABC+ training with multimodality stimulus combinations.

Previous research with keylight conditioned stimuli has revealed that pigeons failed to show inhibition by Stimulus B over Stimulus C in BC versus C testing after A+, AB–, ABC+ training where Stimulus A and Stimulus Compound ABC had signaled food, and Stimulus Compound AB had signaled no food. Indeed, B slightly facilitated responding to C on the BC trials. The present research addressed the same issue with multimodality stimulus arrangements in autoshaping with pigeons, conditioned suppression with rats, and instrumental discrimination learning with rats. Stimulus B facilitated responding to C if A and B were of the same modality and C was of a different modality. However, B inhibited responding to C if A and C were of the same modality and B was of a different modality, or if B and C were of the same modality and A was of a different modality. These results are correctly predictable by Pearce's configural model with a minor modification. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual learning in flavor aversion: Evidence for learned changes in stimulus effectiveness.

Rats were exposed to the compound flavors AX and BX, presented in alternation, and to CX on a separate block of trials. Generalization to BX after aversion conditioning with AX was less than to CX. An equivalent effect was found when the nature of the common element was changed after preexposure but not when the common element was omitted during preexposure, during conditioning and test, or both. Rats conditioned with X alone again showed less aversion to BX than to CX; similarly, rats conditioned with a novel flavor (Y) showed less aversion to BY than to CY. These effects support the proposal that intermixed preexposure to AX and BX enhances the perceptual effectiveness of their unique features, A and B. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effects of habituation training on compound conditioning are not reversed by an associative activation treatment.

Rats received habituation to either 2 compound flavors (AX and BY; the activation group) or a compound and an element alone (AX and Y; the habituation group). They also received additional presentations of Y alone either after (Experiment 1) or intermixed (Experiment 2) with habituation. In the habituation group, A had undergone habituation whereas B had not; in the activation group, both A and B had undergone habituation, but presenting Y alone should result in associative activation of B and that, according to G. Hall (2003), should increase B's efficacy. A supplementary experiment demonstrated that the presentation of Y does activate a representation of B. In both experiments, an aversion was established to AB, and subsequently the habituation group showed a greater aversion to B than to A. However, in neither experiment was there any indication that the activation group showed a greater aversion to B than to A. These results are inconsistent with the suggestion that the associative activation of a stimulus representation in the absence of the stimulus reverses the effects of habituation training. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Enhancement of responding to A after A+/AX+ training: Challenges for a comparator theory of learning.

Two appetitive Pavlovian conditioning experiments with rats investigated the associative changes that A undergoes in an A+/AX+ blocking procedure. Conditioned responding to A was enhanced relative to stimulus B, which had been conditioned in isolation (B+). This result was interpreted in terms of the formation of a within-compound association between A and X. The results of Experiment 2 supported this conclusion by demonstrating that X had associative strength of its own and, furthermore, that extinguishing X resulted in a similar level of responding to A and B. These results are considered in terms of retrospective revaluation theories of learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Factors determining the effects of associative activation on habituation.

In 2 experiments, rats received flavor-aversion conditioning with two flavors, B and C, to which they had been preexposed. In both experiments, C was preexposed in compound with another flavor in a block of CX trials. In Experiment 1, B was presented in compound with Y, and BY trials were alternated with presentations of Y alone. In Experiment 2, B was presented in compound with X, and BX trials were alternated with presentations of X alone. No difference was detected in Experiment 1 between B and C in the ease with which they conditioned, but in Experiment 2 it was found that B conditioned more readily than C. This latter result is consistent with the hypothesis that experience with the associate of a target stimulus can act to maintain the effective salience of that stimulus; however, the results of Experiment 1 challenge this interpretation or indicate the operation of other factors that limit the effectiveness of this salience modulation process. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conditioned inhibition produced by extinction-mediated recovery from the relative stimulus validity effect: A test of acquisition and performance models of empirical retrospective revaluation.

Empirical retrospective revaluation is a phenomenon of Pavlovian conditioning and human causal judgment in which posttraining changes in the conditioned response (Pavlovian task) or causal rating (causal judgment task) of a cue occurs in the absence of further training with that cue. Two experiments tested the contrasting predictions made by 2 families of models concerning retrospective revaluation effects. In a conditioned lick-suppression task, rats were given relative stimulus validity training, consisting of reinforcing a compound of conditioned stimuli (CSs) A and X and nonreinforcement of a compound of CSs B and X, which resulted in low conditioned responding to CS X. Massive posttraining extinction of CS A not only enhanced excitatory responding to CS X, but caused CS B to pass both summation (Experiment 1) and retardation (Experiment 2) tests for conditioned inhibition. The inhibitory status of CS B is predicted by the performance-focused extended comparator hypothesis (J. C. Denniston, H. I. Savastano, & R. R. Miller, 2001), but not by acquisition-focused models of empirical retrospective revaluation (e.g., A. Dickinson & J. Burke, 1996; L. J. Van Hamme & E. A. Wasserman, 1994). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Encoding specific associative memory: Evidence from behavioral and neural manipulations.

Within-subjects procedures with rats assessed the associative structures acquired during conditioning trials in which the interval between the stimuli and food was either short or long (i.e., A–10 s→food and B–40 s→food). In Experiments 1 and 2, after these conditioning trials, A and B served as second-order reinforcers for 2 further stimuli (i.e., X→A and Y→B); whereas Experiment 3 used a sensory preconditioning procedure in which X→A and Y→B trials occurred before the conditioning trials, and rats were finally tested with X and Y. In each experiment, Y elicited greater responding at test than did X. This finding supports the contention that the long-lived trace of B (associated with food on B–40 s→food trials) is more similar to the memory of B that was associatively provoked by Y, than is the short-lived trace of A (associated with food on A–10 s→food trials) to the memory of A that was associatively provoked by X. These conclusions were reinforced by the effects of a neural manipulation that disrupted discrimination learning involving the short traces of stimuli but not the long traces of the same stimuli. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Feature-positive discrimination learning.

In Experiments 1, 2, and 3, pigeons were trained with an ABC+ BCo discrimination, in which three stimuli, A, B, and C, were presented together and paired with food, and the compound BC was followed by nothing; they were also trained with a DEF+ Eo Fo discrimination in which stimuli E and F were presented separately and followed by nothing, whereas the compound DEF was paired with food. On completion of discrimination training, test trials with the feature A consistently revealed a higher rate of responding than with D. In Experiment 4, reinforced presentations of D were intermixed with the DEF+ Eo Fo discrimination. Test trials revealed that E enhanced responding when it was paired with F, but it had the opposite effect when paired with D. The results are seen as being more consistent with a configural than an elemental model of conditioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of similarity in human associative learning.

In 2 experiments, humans received sequences of patterns that were similar (AX→BX, AY→BY, AZ→BZ) or dissimilar (CX→DY, CY→DZ, CZ→DX). The patterns were portrayed as bugs that could be eliminated with 2 insecticide sprays (red or blue). Either spray eliminated bugs with Features A and C, and participants learned by trial and error to use one spray (e.g., red) to eliminate bugs with Feature B and the other spray (e.g., blue) to eliminate those with Feature D. In Experiment 1, participants' spray choice for bugs with Feature A came to match that used to eliminate bugs with Feature B, but there was no such associative transfer between Features C and D. That is, similarity promoted associative transfer of responding between paired patterns when the features used to manipulate similarity (i.e., X, Y, and Z) were irrelevant. In Experiment 2, in which X, Y, and Z were relevant to the solution of configural discrimination, similarity hindered such associative transfer. These results complement those found in pigeons (R. A. Rescorla & D. J. Gillan, 1980) and indicate that similarity should not be accorded independent status as a principle of associative learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Supernormal conditioning.

In Experiment 1, rats received an A+AX° discrimination in which food was presented after Stimulus A by itself but not after a simultaneous compound of A with Stimulus X. AX was then paired with food in a 2nd stage, followed by test trials with A alone. Responding on the test trials with A was more vigorous than during a control stimulus that had been consistently paired with food. The remaining experiments were of similar design to Experiment 1, except that the 2nd stage also contained conditioning trials with X. The results from the test trials were essentially the same as for Experiment 1. The high level of responding during the test trials with Stimulus A is regarded as evidence of supernormal conditioning. Overall, the results are more consistent with a configural than an elemental theory of conditioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Relative validity of contextual and discrete cues.

Contextual conditioning during relative validity training was explored in 3 experiments that used an appetitive Pavlovian conditioning preparation with rats. Magazine entries were the conditioned response. In Experiment 1, true-discrimination (TD: AX+, BX–) training generated weaker conditioning of X than did pseudodiscrimination (PD: AX+/–, BX+/–) training. The context showed a similar relative validity effect. Also, both PD training and simple partial reinforcement (X+/–) reduced contextual conditioning more than did unsignaled food, a demonstration of relative validity using partial reinforcement. Experiments 2 and 3 used within-subject and between-subjects designs, respectively, and showed that relative validity was determined by the summation of differences in conditioning to both the common element (X) and the context. The results are consistent with an attentional model or with a computational comparator model but not with the Rescorla-Wagner (R. A. Rescorla & A. R. Wagner, 1972) model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Contextual modulation of stimulus generalization in rats.

One connectionist analysis of the acquired equivalence/distinctiveness of cues assumes that when similar compounds (e.g., AX and BX) are paired with the same outcome (e.g., food, +; or no food, ?), their components come to activate the same configural unit (ABX). When these compounds are paired with different outcomes, their components will come to address different units. Here, rats received appetitive training with eight compounds (e.g., AX+, BX+, CX?, DX?, AY+, BY?, CY?, DY+) that should generate the following configural units: ABX, CDX, ADY, and BCY. In Experiment 1, rats then received aversive conditioning to A, which should activate and revalue representations ABX and ADY. Subsequently, compounds that provided dual activation (i.e., BX and DY) of one of the revalued configural units (ABX and ADY) were shown to elicit greater fear than those compounds that provided a single source of activation to each unit (i.e., DX and BY). Experiment 2 confirmed and extended these findings. These results provide support for the connectionist analysis outlined above and are consistent with the application of this approach to the acquired equivalence/distinctiveness of cues. (PsycINFO Database Record (c) 2010 APA, all rights reserved)