Showing papers in "Journal of Experimental Psychology: Animal Behavior Processes in 1977"

Conditioned stimulus as a determinant of the form of the Pavlovian conditioned response

Abstract: The role of the conditioned stimulus (CS) as a determinant of the form of the Pavlovian conditioned response (CR) was investigated in five experiments. Both stabilimeter measures of general activity and detailed observations of the behavior of the rat subjects in the presence of CSs anticipatory to a food unconditioned stimulus (US) were obtained. In Experiment 1, substantially different behaviors to light and tone CSs were observed; further, these differences were found to be dependent on specific learning experience rather than on the mere presence of different stimulation at the time of response evocation. Experiments 2 and 3 investigated the possibility that there was considerable communality of learning to light and tone CSs despite their evoking different CRs. In Experiment 2, prior conditioning of either the tone or light CS was found to block the acquisition of various behaviors to the added element when a light-tone compound stimulus was reinforced, even though the pretrained stimulus did not itself evoke those behaviors. In Experiment 3, the nature of second-order conditioned responding was found to be similar regardless of which first-order CS was used as the reinforcer. Additionally, the reinforcing powers of the light and tone CSs were found to summate. Experiments 4 and 5 examined behaviors to a variety of visual and auditory stimuli paired with food. Stimulus modality and the localizability and vertical location of visual stimuli were found to influence conditioned responding. These results suggested that in this conditioning situation, similar learning of a CS-US relation may be displayed in different overt CRs, depending on the nature of the CS.

Bisection of temporal intervals

Abstract: Eight rats were trained to make one response if a signal was shorter than a criterion duration and a different response if the signal was longer than the criterion. When exposed to intermediate durations, the rats bisected the interval at the geometric mean and the difference limen divided by the geometric mean was a constant. The rats learned new temporal discriminations more easily when the response maintained its relative, rather than its absolute, meaning. These data were interpreted in terms of a model of an internal clock that included a clock, a criterion, and a response rule.

Morphine tolerance acquisition as an associative process.

Abstract: The results of several experiments supported the proposal that morphine analgesic tolerance is a manifestation of an association between the drug administration ritual and the systemic effects of the drug: (a) Presenting environmental cues previously associated with morphine, but without the drug, attenuated established tolerance (ie, morphine tolerance can be extinguished), (b) repeated presentations of the morphine administration procedure, prior to its pairing with the opiate, retarded the acquisition of tolerance (ie, morphine tolerance is subject to "latent inhibition"), and (c) placebo sessions interspersed between morphine sessions deleteriously affected the development of tolerance (ie, morphine tolerance is subject to the decremental effects of partial reinforcement) These findings appear inexplicable by most traditional theories of tolerance, which do not emphasize the role of drug-associated environmental cues in the development of tolerance Additionally, it is suggested that the conditioning analysis of tolerance is congenial with a current view of habituation, and there may be a similar associative basis for the response decrement to both endogenous and exogenous iterative stimulation

Stimulus similarity as a determinant of Pavlovian conditioning.

Abstract: Three experiments carried out second-order Pavlovian conditioning using either similar or dissimilar first- and second-order stimuli. Experiments 1 and 2 used rat subjects in a conditioned suppression and an appetitive conditioning preparation, respectively. Experiment 3 used pigeons in an auto-shaping procedure. All three experiments were designed to identify the effects of similarity upon conditioning as distinct from its effects upon sensitization or stimulus generalization. Each experiment found superior conditioning when similar stimuli were paired. Several theoretical implications of these findings are discussed.

Selective suppression of drinking during a limited period following aversive drug treatment in rats.

Abstract: Administration of lithium chloride disrupted the intake of flavored solutions but not water in rats. This intake suppression was directly related to the amount of lithium administered (Experiment 1), occurred with both palatable and unpalatable novel saccharin solutions (Experiment 2), but was only observed if subjects were tested starting less than 75 min. after lithium treatment (Experiment 3). Twenty-five daily exposures to saccharin did not attenuate the effect (Experiment 4). However, in saccharin-reared and vinegar-reared rats, lithium did not disrupt consumption of the solutions these subjects had access to throughout life, even though suppressions of intake were observed when these subjects were tested with novel flavors (Experiment 5). The selective disruption of drinking is interpreted as a novelty-dependent sensitization reaction to the discomfort of aversive drug administration.

Enhancing the expression of flavor neophobia: some effects of the ingestion-illness contingency.

Abstract: Four experiments investigating factors contributing to enhanced ingestional neophobia are reported. Rats administered lithium chloride following ingestion of a novel coffee solution showed an enhanced neophobia reaction to vinegar and casein. This enhancement was specific to the novelty of both the conditioning and test fluids and was not observed in animals receiving noncontingent toxicosis. Poisoning alone, however, mediated a nonspecific fluid suppression that persisted for approximately two drinking sessions following treatment. In contrast to other experiments, the operation of generalization was detected only when a novel flavor was the test fluid, suggesting that neophobia enhancement is at least partially mediated by a conditioned novelty aversion resulting from the novel flavor-lithium contingency.

Taste-Aversion Conditioning with Expected Versus Unexpected Drug Treatment.

Abstract: Following differential conditioning in which a drug-predictive taste solution (D) infused into the oral cavity of rats was followed by a lithium injection and a no-drug-predictive solution (ND) was not reinforced, animals received a backward pairing between lithium and a novel saccharin flavor. Subjects infused with either the D solution or tap water immediately before backward conditioning learned weaker saccharin aversions than animals infused with the ND solution and animals given no infusion at this time (Experiments 1 and 3). These latter groups did not differ from each other (Experiment 3). The interference with aversion learning produced by water infusion appeared to be due to conditioned excitation that accrued to sensations of the infusion process. Extinction of the infusion sensations eliminated blocking produced by the infusion of water (Experiments 4 and 5). The blocking of saccharin-aversion learning produced by infusion of the D solution was due, to a large extent, to the conditioned aversiveness of the D taste. Extinction of the aversion to the D taste eliminated the interference with saccharin conditioning (Experiment 2), whereas extinction of the excitatory properties of the infusion process did not prevent the blocking of conditioning by infusion of the D solution (Experiment 5). These results are inconsistent with suggestions that taste-aversion learning is a primitive form of conditioning; rather, they demonstrate the influence of informational variables on conditioned taste aversions.

Paradoxical Effects of Proximal Unconditioned Stimulus Preexposure: Interference with and Conditioning of a Taste Aversion.

Abstract: Taste aversions were conditioned in rats by giving the subjects an injection of lithium following exposure to saccharin. Treatment with lithium shortly (30 to 60 min.) before such a conditioning trial disrupted the taste-aversion learning produced by the postsaccharin drug injection. In Experiment 1, this interference effect was found to be a monotonically decreasing function of the preexposure-to-conditioning interval. The greatest disruption of conditioning was observed with a 30-min. preexposure-to-conditioning interval, and no interference occurred if the preexposure was administered 1 or 2 days before conditioning. These results suggest that in addition to the more durable effects of unconditioned stimulus (US) preexposure emphasized by previous investigators, US preexposure also activates temporary mechanisms that likewise attenuate subsequent conditioning. Experiment 2 demonstrated that lithium given before saccharin exposure disrupts the conditioning produced by a postsaccharin drug injection even if the presaccharin injection would itself otherwise be effective in producing a "backward" conditioned saccharin aversion. This outcome indicates that proximal US preexposure can have two opposite and paradoxical effects: It can interfere with as well as condition a taste aversion.

Pairing novel exteroceptive cues and illness reduces illness-induced taste aversions.

Abstract: Four experiments are reported that lead to the conclusion that pairing novel exteroceptive stimulation (placement into a black compartment) with a poison (lithium chloride) attenuates the development of an aversion to a taste (saccharin) subsequently paired with the poison. Such an attenuation effect occurs whether the exteroceptive cues are present or absent when the taste-poison pairing is administered. Interpretation and implications of this finding are discussed.

Disruption of a taste familiarity effect by novel exteroceptive stimulation.

Abstract: Preexposed or familiar tastes are normally retarded relative to novel tastes in acquiring aversive properties as a consequence of being paired with an illness-inducing event. Four experiments are reported which demonstrate that such a taste familiarity effect can be significantly disrupted by exposing the animal to novel exteroceptive stimulation just prior to conditioning with the familiar taste. Implications of this finding for theories of taste aversion learning are discussed, and two potential theoretical accounts of the data are suggested.

Illness-alone exposure as a source of interference with the acquisition and retention of a taste aversion.

Abstract: Four studies were conducted to explore the effects of unpaired lithium chloride (LiCl) injections, the unconditioned stimulus (US), on the acquisition and retention of a taste aversion. In Experiment 1, subjects were preexposed to a US; for one group the US was paired with a distinctive taste, whereas for a second group it was not. Following this preparation, both groups received the US paired with a novel taste. Only the US-alone group showed a retardation of subsequent taste-aversion conditioning. Experiment 2 indicated that an exposure to LiCl without a specific gustatory cue will interfere with the avoidance of a specific taste, regardless of whether the US experience occurs before or after a single taste-LiCl pairing. Following sucrose-LiCl pairings in Experiment 3A, LiCl-alone exposures retroactively interfered with the retention of the prior aversion to sucrose, with the level of post-US interference becoming an increasing function of the number of US-alone experiences. In Experiment 3B, the association of sucrose with LiCl did not interfere with the development of an almond aversion, whereas LiCl-alone exposures following the acquisition of a sucrose aversion proactively interfered with the development of a second taste aversion (almond). It is suggested that a physiological explanation will not adequately account for the present results of these experiments. The results are discussed within the framework of alternative associative models.

Aftereffects of Lithium-Conditioned Stimuli on Consummatory Behavior.

Abstract: Exposure to taste or spatial cues previously paired with lithium administration resulted in more drinking during a test session started 15 min. later than did exposure to stimuli previously presented in the absence of drug treatment (Experiments 1, 2, 4, and 5). This outcome reflected an elevation of intake above baseline levels (Experiment 1) and required the presence of the lithium-paired cues rather than merely a history of lithium injections (Experiments 1, 2, 4, and 5). The increased drinking was evident in tests with novel (Experiments 1, 4, and 5) as well as familiar (Experiment 2) palatable solutions and was not attributable to a greater degree of thirst in subjects exposed to the lithium-predictive cues (Experiments 4 and 5). The phenomenon was attenuated by extinction of the lithium-conditioned stimuli (Experiment 3). However, the increased drinking aftereffect probably was not a result of the conditioned aversiveness of lithium-predictive cues, since shock-conditioned stimuli did not elicit enhanced consumption (Experiment 5). Various explanations of the effect are discussed.

Posttrial reinstatement of the CS in Pavlovian conditioning: facilitation or impairment of acquisition as a function of individual differences in responsiveness to the CS.

Abstract: Gray and Appignanesi reported that conditioning to an element of a compound conditioned stimulus (CS) was facilitated when the compound not only preceded the unconditioned stimulus (US) but was briefly reinstated shortly after US termination. The manipulation was embedded in a "blocking" design, and the effect was interpreted as being peculiar to such a situation. The present study reports five experiments, using rats in a conditioned emotional response (CER) paradigm, aimed at further evaluating the effects of CS reinstatement. In a blocking experiment patterned after that of Gray and Appignanesi, reinstatement was observed to have a decremental rather than an incremental effect on conditioned responding. In four experiments involving simple conditioning with unitary CSs, reinstatement was observed to have either an incremental or decremental effect, depending upon the subject's preconditioning responsiveness to the CSs involved. Possible mechanisms for such variable effects are discussed without obvious resolution.

Taste aversions conditioned by the aversiveness of insulin and formalin: role of CS specificity.

Abstract: Experimenters in the past have reported that when insulin is used as the unconditioned stimulus (US), rats will learn an aversion to a sodium chloride but not a sucrose solution, whereas with formalin as the US, they will learn an aversion to a sucrose but not a saline solution. The present experiments failed to confirm these findings. Aversions to sucrose were conditioned with insulin and aversions to sodium chloride were conditioned with formalin. The use of a more concentrated sucrose solution in the present study may have been responsible for the successful sucrose-aversion conditioning with insulin. Although the source of the discrepancy in findings concerning aversion conditioning with formalin remains unclear, experiments ruled out numerous possibilities. These experiments also showed that sodium chloride aversion conditioning with formalin is a highly robust phenomenon that occurs with a variety of conditioned stimulus durations and formalin doses, with distributed and massed training, in male and female rats, and even if saline is not the only novel solution presented during conditioning. Furthermore, the aversion can be detected with both single-stimulus and choice test procedures.