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This article examines the effect of distraction on the performance of a visual search task involving the identification of a unique shape placed on a display of homogeneous distractor shapes. Findings indicate that performance is decreased in conditions where the target shape was formerly a distractor due to latent inhibition

Four experiments were conducted with rats involving serial feature-positive discrimination training (positive occasion setting) in a Pavlovian conditioned lick suppression context. The conditions under which acquisition of feature-positive discrimination is retarded by pretraining experience were investigated. Results suggest that occasion setting is the product of interaction among Pavlovian associations, and not due to some distinct 'higher-order' process.

Experiments with laboratory rats indicate that the context shift effect may change over time. Rats were used in a passive avoidance task, then half of them tested in the same training context and the other half in a different context. Different context testing at 1 and 21 days after learning demonstrated the context shift effect, while testing at 7 and 14 days did not.

Associations made between unconditioned stimuli and conditioned stimuli are determined by context. Overshadowing and extinction of overshadowing were used in different contexts with male and female rats. Response to stimuli when overshadowing and extinction were in the same context was different from response when overshadowing and extinction were in different contexts.

Associating an illness in an environmental context sometimes depends on fluid consumption and sometimes it does not, according to an experiment conducted on rats. The aversion to fluids may have been conditioned during the experiment. The experiment involved giving lithium chloride to rats as a way to induce nausea under controlled circumstances.

The conditioned stimulus (CS) complex creating the blocking effect in a rabbit's nictating membrane response is made of contextual and discrete components, established by three experiments. The first experiment showed that changing the single stimulus training context before compound training lessened the blocking effect, while the second and third experiments measured levels of response to the blocked stimulus.

Competition between contextual occasion setting and associative processes was indicated by experiments with rats using appetitive conditioning. The presence of a discrete predictive stimulus interfered with occasion setting by contextual stimuli. The rats were separated into groups that learned to predict nonreinforcement of an auditory target stimulus based on contextual stimuli (CTX), a visual stimulus that was compounded with the target (CI), or both (CTX+CI). A second auditory target was inconsistently reinforced. The visual stimulus controlled behavior in both the CI and CTX+CI groups, while the contextual stimuli controlled behavior of the CTX group.

Two experiments demonstrated the occurrence of a renewal effect in conditioned taste aversion of rats, as in other forms of conditioning. The renewal effect occurs when the conditioned taste aversion is extinguished in a context different from the conditioning context, followed by partial renewal of aversion on return to the original conditioning context. The effect is not observed when the context change occurs without prior conditioning and extinction of the flavor-illness association.

Rats acquired conditioned aversion to the context in which they received injections of lithium chloride (LiCl). This context conditioning blocked acquisition of an aversion to sucrose, when sucrose was injected in the home cage, then LiCl was administered after the rats were transferred to the context. Blocking was associated with cues related to the particular place, not to cues such as transportation or time of day. This series of experiments confirms and extends the results of Best et al (1984), and additional implications are also discussed.

Results of experiments with rats suggest that inhibition occurs following negative occasion setting through context-specific association of the target with the unconditioned stimulus. The experiments were designed to explore how a change of context affects inhibition acquired through feature-negative (FN) discrimination, either serial or simultaneous. Inhibition associated with the feature was not disrupted by the context switch, but loss of inhibition occurred in relation to the target. The effect was more complete after the serial procedure than after the simultaneous FN discrimination.

A study of rats' responses to signalled or unsignalled aversive shock treatments indicated differences between rats' reactions to a context preference test and freezing behavior. The first experiment used as its signal a lighted unconditionally aversive context and a shock context, while the second experiment tested the rats' freezing behavior when confined to the shock context. Rats which received signals in the brightly lit environment spent more time in that environment, while the freezing tests failed to produce noticeable difference in behavior.

An experiment studying the reaction of rats to signaled delay of reinforcement indicated that unsignaled noncontingent feedings created the most significant decrease in response. The first experiment demonstrated that exposure to the conditioning context after training was sufficient to create an attenuated response rate during the test for extinction. A second experiment demonstrated decreased responses when the rats were exposed to cues signalling noncontingent reinforcements, or following unsignaled noncontingent feedings.

Drug states, contextual cues, and different flavors can all modulate taste aversion learning. While drug states have this effect more quickly, the other methods eventually proved as effective in three experiments. These results dissociate Pavlovian conditioning and a higher-order learning system, though representation within the latter remains unclear. Occasion-setting task performance is not due to either simple excitation or learning about a unique compound cue.

Rats' vulnerability to later gastric ulceration from stress increased when a shock was followed by a rest period in the shock apparatus, but not when a waiting period in the apparatus preceded the same amount of shock. Results indicate that the effect on ulceration is the result of psychological processes rather than simply the amount of physical trauma. The results also provide evidence for backward conditioning, since aversion was associated with the context following the shock, but not with the context preceding it. It is apparent that the effect of time spent in the shock apparatus both before and after shock must be considered in any similar experiments.

Competition occurred between inhibitory conditioning to a punctate stimulus and acquisition of negative contextual occasion setting in two experiments using a Pavlovian discrimination procedure with rats. Relative salience of the competing stimuli determined the outcome. The results contradict previous appetitive blocking studies which found no interaction between positive occasion-setters and excitatory stimuli and suggest that higher-order and simple associative memory systems are not independent.

Two taste aversion learning experiments with rats provided evidence that association of the context and unconditioned stimulus rather than occasion setting accounts for contextual effects. The first experiment found reduced consumption of a flavor paired with lithium chloride but not in a context without lithium, demonstrating learning of contextual discrimination. In the second experiment conditional control of flavor consumption persisted at a lower magnitude after extinction of the paired-lithium context. The context effect was eliminated after extinction of the conditioned taste aversion.

Delayed matching-to-sample experiments were used to test aspects of pigeons' memory for duration involving length of delay and intertrial intervals. As predicted by the relative duration hypothesis, a shorter intertrial interval was associated with more systematic errors in response to manipulations of delay intervals. Varying the intertrial and delay intervals during training did not significantly affect the acquisition of a temporal reference memory.

The effects of intertrial unconditioned stimulus (CS) presentations on the acquisition of keypecking to a conditioned stimulus (CS) paired with either the same or different appetitive US was examined in two experiments with pigeons. In the first experiment it was found that intertrial grain presentations prevented acquisition of conditioned responding to both a CS predictive of water and a CS predictive of grain. In contrast, intertrial water presentations did not prevent the acquisition of responding to a CS predictive of grain, although the intertrial water presentations did prevent the acquisition of responding to a CS predictive of water. Experiment 2 replicates the results of Experiment 1 and also shows that in the absence of any intertrial events the pigeons acquired responding to both the CS for grain and the CS for water. The results of these experiments are discussed in terms of context blocking.

Three experiments used conditioned lick suppression with rats in order to investigate the necessary conditions for obtaining occasion setting by context. Experiment 1 sought occasion setting by context as a product of conditioned-stimulus (CS) excitatory training only. Associative summation of the CS and context was observed, but no difference in responding inside versus outside the CS training context was found after devaluing direct context-unconditioned stimulus (US) associations and controlling for both familiarization and generalization decrement between training and nontraining contexts. In Experiment 2, two stimuli were conditioned in separate contexts, and subsequently each CS was or was not extinguished either in the same context in which it had been trained or in the training context of the other CS. This procedure equated the associative values of the two contexts during acquisition, extinction, and testing. No occasion setting by context was seen either with or without extinction of the CSs. In Experiment 3, a renewal paradigm was used in which a single CS was trained in context A and extinguished in Context B. Testing showed renewed responding to the CS in Context A. A context-CS summation test using an unambiguous CS trained in a third context found Contexts A and B to be equally excitatory. We hypothesize that the lack of occasion setting in Experiment 2, in contrast to that of Experiment 3, resulted either from extinction of the positive occasion-setting properties of the two contexts as a consequence of their both being sites of CS extinction or a failure of a contextual occasion setter to carry information about the particular stimulus qualities of a given CS with which it was conditioned (i.e., occasion setters act on US representations, not particular CS-US associations).

We used summation tests in conditioneed suppression with rats to evaluate the effects of two preconditioning manipulations on the acquisition of associative strength by a backward conditioned inhibitory stimulus (CS-) that followed an unconditioned stimuls (US). Two backward CS-s were establisheed within subjects; onee backward CS- followed a US that was always signaled by a conditioned excitatory stimulus (CS+), a second backward CS- followed a US that was never signaleed. In Experiment 1, prior conditioning of the forward CS+ before backward conditioning enhanced inhibitory conditioning to the backward CS- that followed the signaled US. An opposite effect was observed on the unsignaled trials; backward inhibitory conditioning was impaired by preconditioning of the forward CS+. In Experiment 2, prior conditioning of the context, which involved embedding many USs within the context before backward conditioning, facilitated later inhibitory conditioning with both signaled and unsignaled USs. This geneeral facilitative effect was specific, in Experiment 3, to the preconditioned context and was not evident in a nonpreconditioned context. We conclude that backward inhibitory conditioning with a signaled US is multiply determined by contextual and forward CS+ based inhibitory processing. These data are consistent with the preconditions of Wagner's standard operating procedure (SOP) model, as well as a modified veersion of Miller and Schachtman's comparator hypothesis of response generation.

Three experiments with rat subjects examined the effects of contextual stimuli on performance in Pavlovian aversive-to-appetitive and appetitive-to-aversive transfer. A 30-s tone conditioned stimulus (CS) was first paired with either a shock or food pellet unconditioned stimulus (US) in one phase and then paired with the other US in a subsequent phase. Aversive and appetitive conditioning were indexed by the observation of freezing and headjerking, respectively. In aversive-appetitive transfer (Experiment 1), a context switch following Phase 1 aversive conditioning reduced the retardeed appetitive conditioning ordinarily observed in Phase 2. In addition, a return to the Phase 1 context after completion of Phase 2 caused renewed Phase 1 responding and decreased Phase 2 responding. In appetitive-aversive transfer (Experiments 2 and 3), a context switch following Phase 1 appetitive conditioning had no effect because neither positive nor negative transfer with Phase 2 aveersive conditioning was observed in this situation. However, a return to the Phase 1 conditioning context after completion of Phase 2 caused renewed Phase 1 responding at 1- and 28-day retention intervals (Experiment 2). These results are consistent with a role for context as a retrieval cue for memories corresponding to different pahses. This view is discussed along with more traditional associative perspectives on contextual control.

A conditional taste aversion experiment examined the role of the retention-interval context on the modulation of long-delay latent inhibition (LI). It was observed that the critical element for producing super-LI is the distinctiveness of the long-delay context relative to the other experimental contexts.

Rats were trained on a conditional discrimination task in which saccharin was paired with LiCl in one context but paired with saline in another context. Data suggest that occasion setting and not simple context conditioning is the mechanism by which contextual cues modulated the consumption of fluid.

Laboratory evidence and cultural phenomena indicate that the behaviors evoked by a word and its referent could be quite similar to each other. The study could possibly help to understand the determinants of response frequency in symbolic understanding.