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PubMed1966

Stimulus aspects of aversive controls: long term effects of suppression procedures.

Five years ago, pigeons trained to peck a key for food were periodically presented with a 1000 cps tone which ended with electrical shock. They were then tested for the stimulus generalization of conditioned suppression. After an interruption of 2.5 yr, another series of generalization tests showed no loss of suppression. The present study was conducted 1.5 yr later to retest the effect of an extended interruption on retention of suppression. It was found, again, that suppression did not decline over time. The present paper, which summarizes the earlier data and reports the most recent findings, provides an overview of the extended behavioral consequences of the original aversive procedures administered five years ago.

Animals↗
PubMed1975

Stimulus-specific contrast effects during operant discrimination learning.

In two experiments, pigeons' responding was equally reinforced in the presence of four line-orientation stimuli. Responding was then reinforced when only two of the four orientation stimuli were present; the remaining two orientations appeared during extinction. Response rates were often highest in the stimulus adjacent to the orientations presented during extinction and often lowest in that orientation adjacent to the orientations presented with reinforcement. These effects were stronger and more persistent when the stimuli were separated by a smaller angle, rendering the discrimination more difficult. These and other data suggest that discrimination training may not be accurately explained in terms of the simple effects of reinforcement and nonreinforcement associated with isolated stimuli, nor by accounts that depend upon stimulus generalization. Recent accounts of contrast that depend upon "emotionality" produced by nonreinforced responding or upon reinforcement-elicited responses are also difficult to apply to these data.

Journal Article↗
PubMed1985

Sign-tracking with an interfood clock.

Food was presented to pigeons, irrespective of their behavior. The fixed 60-s interfood interval was segmented into ten 6-s periods, each signaled by a distinctive stimulus color, ordered by wavelength. This "interfood clock" reliably generated and maintained successively higher rates of key pecking at stimuli successively closer to food. Under extinction, key pecking ceased. When the standard stimulus sequence was changed to a different sequence for each bird, accelerated responding again emerged and was sustained under each of the new color sequences. However, responding was neither maintained nor acquired when each successive interfood interval provided a different random sequence of the ten stimuli. Thus, the interfood clock generated and maintained sign-tracking under stimulus control, and the resulting behavior was attributable neither to stimulus generalization nor to a simple temporal gradient.

Journal Article↗
PubMed1993

Assessing control by elements of complex stimuli in delayed matching to sample.

A series of six experiments examined delayed identity matching-to-sample performances of subjects with mental retardation. The stimuli were either one or two simultaneously displayed forms. When the reinforcement contingencies required that only one form exert discriminative control, all subjects achieved high accuracy scores. However, accuracy scores were substantially lower when the contingencies required discriminative control by two forms, suggesting restricted stimulus control. The decline in matching accuracy appeared to reflect selective losses of conditional control by sample stimuli and shifts in control to features of the comparison stimulus displays. The experiments suggest improved techniques for assessing control by complex stimuli and for evaluating the effects of procedures that seek to broaden restricted stimulus control. The results challenge interpretations based on stimulus-generalization decrement or shared attention.

Adolescent↗
PubMed1999

Support for a theory of memory for event duration must distinguish between test-trial ambiguity and actual memory loss.

Staddon and Higa's (1999) trace-strength theory of timing and memory for event duration can account for pigeons' bias to "choose short" when retention intervals are introduced and to "choose long" when, following training with a fixed retention interval, retention intervals are shortened. However, it does not account for the failure of pigeons to choose short when the intertrial interval is distinct from the retention interval. That finding suggests that stimulus generalization (or ambiguity) between the intertrial interval and the retention interval may result in an effect that has been attributed to memory loss. Such artifacts must be eliminated before a theory of memory for event duration can be adequately tested.

Animals↗
PubMed1987

Pathogenesis of inflammation. Effects of the pharmacological manipulation of arachidonic acid metabolism on the cytological response to inflammatory stimuli.

It is generally accepted that non-steroidal anti-inflammatory drugs (NSAIDs) act by the inhibition of prostaglandin biosynthesis. However, this hypothesis may not apply to all NSAIDs at all doses. It has thus been proposed that, in high doses, NSAIDs counteract inflammation by the inhibition of the activity of inflammatory cells such as the neutrophil. Neutrophils are activated by a 'twin signal' which is a part of a general stimulus response coupling mechanism involving phospholipid remodelling. This 'twin signal' consists of the mobilisation of intracellular calcium and the activation of protein kinase C. NSAIDs inhibit the aggregation of neutrophils in vivo and in vitro, and show additive effects with stable prostaglandins on the inhibition of the generation of superoxide anion, a product of inflammation. Binding studies have shown that the mechanism of this effect appears to be an interference with the ligand-receptor site modulated by the G protein. Activation of the cells of the marine sponge, which are not responsive to stable prostaglandins and do not contain a cyclo-oxygenase, can be inhibited by NSAIDs. Therefore, further investigation of this interesting hypothesis should help to clarify the precise mechanism of the anti-inflammatory effects of these drugs.

Animals↗
PubMed1982

Cultural differences in preferences for shapes.

It was predicted that since there is less sexual restraint in Jamaica the sex difference in shape preference should be larger for native adult Jamaicans than Caymanian adults. Pairs of drawings of a "female" and a "male" object, depicted according to the theory of sexual symbolism, were shown to 200 subjects, who indicated which of each pair they preferred. The larger sex difference found among Jamaicans was interpreted in terms of primary sexual stimulus generalization.

Adolescent↗
PubMed1983

Temporal correlates of discrimination learning.

The relationship between human temporal behavior and learning was investigated by means of an experimental design which measured temporal behavior using the methods of reproduction and production as possible correlates for a complex-form of discrimination-reversal learning. The results indicated that the method of reproduction is a temporal correlate of original learning and that the method of production is a temporal correlate of reversal learning. The theoretical explanations proposed for these results employed the mechanisms of conditioning, extinction, and stimulus generalization, the intervening variables of excitation and inhibition and the Pavlovian levels of behavioral organization of the first and second signalling systems.

Adult↗
PubMed1994

Blocking in Pavlovian conditioning: effect of prior excitatory conditioning to a stimulus extraneous to compound conditioning.

The effect of prior excitatory conditioning to a stimulus not included in the compound conditioning phase of the typical blocking experiment was assessed in three CER studies. The first experiment, in which rat subjects received A+, C+, or a combination of A+/C+ trials prior to AB+ conditioning, showed that A+/C+ or C+ training produced as robust blocking as A+ training relative to a control group with no prior conditioning. A second experiment which was designed to assess the role of background cues in mediating the blocking effect indicated that background cues were not responsible for the A+ or C+ effects, while a third experiment showed these same effects were not mediated by stimulus generalization. The findings of these experiments are interpreted in the context of pseudoconditioning-induced rehearsal of a US representation in short-term memory.

Animals↗
PubMed1994

Efficacy of lithium chloride in the taste-aversion conditioning of young-adult and old-age rats.

An absolute amount of a LiCl US was administered to 24 young-adult and 24 old-age rats during taste-aversion conditioning to determine whether the superior performance of old-age rats, when a 1% body-weight injection of a LiCl US is administered 3 hr. after a saccharin CS, is due to age-related differences in US intensity or the efficacy of LiCl. The aversion conditioned in old-age rats with a 3-hr. CS-US interval and an absolute amount of LiCl was still significantly greater than that in young adults suggesting that age-related differences in US intensity or the efficacy of LiCl cannot explain the superior performance of old-age rats. Possibly, old-age rats forget the specifics of the CS more than young adults and, thus, older animals show greater stimulus generalization to the substantially different test stimuli.

Age Factors↗
PubMed2000

Asymptotic judgment of cause in a relative validity paradigm.

We report three experiments in which we tested asymptotic and dynamic predictions of the Rescorla-Wagner (R-W) model and the asymptotic predictions of Cheng's probabilistic contrast model (PCM) concerning judgments of causality when there are two possible causal candidates. We used a paradigm in which the presence of a causal candidate that is highly correlated with an effect influences judgments of a second, moderately correlated or uncorrelated cause. In Experiment 1, which involved a moderate outcome density, judgments of a moderately positive cause were attenuated when it was paired with either a perfect positive or perfect negative cause. This attenuation was robust over a large set of trials but was greater when the strong predictor was positive. In Experiment 2, in which there was a low overall density of outcomes, judgments of a moderately correlated positive cause were elevated when this cause was paired with a perfect negative causal candidate. This elevation was also quite robust over a large set of trials. In Experiment 3, estimates of the strength of a causal candidate that was uncorrelated with the outcome were reduced when it was paired with a perfect cause. The predictions of three theoretical models of causal judgments are considered. Both the R-W model and Cheng's PCM accounted for some but not all aspects of the data. Pearce's model of stimulus generalization accounts for a greater proportion of the data.

Adult↗
PubMed1994

Comparing models of rule-based classification learning: a replication and extension of Shepard, Hovland, and Jenkins (1961).

We partially replicate and extend Shepard, Hovland, and Jenkins's (1961) classic study of task difficulty for learning six fundamental types of rule-based categorization problems. Our main results mirrored those of Shepard et al., with the ordering of task difficulty being the same as in the original study. A much richer data set was collected, however, which enabled the generation of block-by-block learning curves suitable for quantitative fitting. Four current computational models of classification learning were fitted to the learning data: ALCOVE (Kruschke, 1992), the rational model (Anderson, 1991), the configural-cue model (Gluck & Bower, 1988b), and an extended version of the configural-cue model with dimensionalized, adaptive learning rate mechanisms. Although all of the models captured important qualitative aspects of the learning data, ALCOVE provided the best overall quantitative fit. The results suggest the need to incorporate some form of selective attention to dimensions in category-learning models based on stimulus generalization and cue conditioning.

Adult↗
PubMed1992

Music-dependent memory in immediate and delayed word recall.

Undergraduate volunteers rated a series of words for pleasantness while hearing a particular background music. The subjects in Experiment 1 received, immediately or after a 48-h delay, an unexpected word-recall test in one of the following musical cue contexts: same cue (S), different cue (D), or no cue (N). For immediate recall, context dependency (S-D) was significant but same-cue facilitation (S-N) was not. No cue effects at all were found for delayed recall, and there was a significant interaction between cue and retention interval. A similar interaction was also found in Experiment 3, which was designed to rule out an alternative explanation with respect to distraction. When the different musical selection was changed specifically in either tempo or form (genre), only pieces having an altered tempo produced significantly lower immediate recall compared with the same pieces (Experiment 2). The results support a stimulus generalization view of music-dependent memory.

Affect↗
PubMed1976

[Studies on anesthetized and nonanesthetized slaughter swine. 1. Blood pressure].

The blood pressure of pigs for slaughter were measured. Onset of electric anaesthesia was followed by blood pressure rise of about 25 per cent. Peak values of 100 per cent in excess of the original pressure were recorded in some cases. Termination of the electric stimulus, generally, was followed by sudden blood pressure drop. The original pressure usually was reached ten seconds from the debleeding puncture. With continued debleeding, it stayed at 75 mm Hg after 50 seconds on average. Extraordinary high rise in blood pressure in response to electric stimulation usually was followed by rapid pressure drop, whereas in cases with moderate rise at the time of anaesthesia the subsequent decline was at slower rates.

Anesthesia↗
PubMed1975

On the narcotic cuing action of fentanyl and other narcotic analgesic drugs.

Using a food-reinforced two-levers operant procedure, rats could be trained to discriminate fentanyl (1.25 mg/kg, p.o., t-60') from solvent (1 ml/100 g B.W., p.o.,t60)treatment. The administration of the other narcotic analgesics bezitramide, dextromoramide, methadone and morphine produced a dose-related stimulus generalization with the standard fentanyl treatment. The results further evidence the validity of the narcotic cue.

Analgesics, Opioid↗
PubMed1989

Effects of competitive and noncompetitive N-methyl-D-aspartate (NMDA) antagonists in rats trained to discriminate NMDA from saline.

Competitive and noncompetitive N-methyl-D-aspartate (NMDA) antagonists and other central nervous system depressants were assessed for their ability to antagonize the discriminative stimulus effects of NMDA in rats trained under a standard two-lever fixed ratio schedule of food reinforcement. The competitive NMDA antagonists, 3-(2-carboxypiperazin-4-yl)propyl-1-phosphonate and NPC 12626 [2-amino-4,5-(1,2-cyclohexyl)-7-phosphonoheptanoate], dose-dependently antagonized NMDA-lever selection at doses that did not affect rates of responding. Conversely, the noncompetitive NMDA antagonists, phencyclidine, MK-801 [(+)-5-methyl-10,11-dihydro-5H-dibenzo(a,d)cyclohepten-5,10-imine maleate] and (+)-N-allylnormetazocine, as well as pentobarbital and diazepa, all reduced response rates dose-dependently without antagonism of NMDA-lever responding. In stimulus generalization tests, NPC 12626 and 3-(2-carboxypiperazin-4-yl)propyl-1-phosphonate at doses higher than those required to antagonize NMDA, often elicited NMDA-lever responding. The mechanisms underlying the similarities in the interoceptive stimuli produced by NMDA and its competitive antagonists remain to be determined. These results indicate that although competitive NMDA antagonists antagonize effects of NMDA without concomitant behavioral disruption, noncompetitive NMDA antagonists and central nervous system depressants are behaviorally disruptive at doses that do not antagonize NMDA. The results provide further evidence for differences in the behavioral profiles of competitive and noncompetitive NMDA antagonists.

Amino Acids↗
PubMed1989

Context-dependent cocaine sensitization: differential effect of haloperidol on development versus expression.

Repeated, intermittent administration of psychomotor stimulants has been shown to produce increasing effects (behavioral sensitization) in many species of animals. In a novel two-day sensitization paradigm, rats that received a single high dose of cocaine (40 mg/kg) compared with saline on day 1 showed an increased locomotor response to a challenge dose (10 mg/kg) on day 2. This effect is conditioned or context-dependent; i.e., it is only observed if the rats received cocaine in an environment similar to the test environment. If the cocaine-induced hyperactivity on day 1 is prevented with pharmacological agents such as haloperidol and diazepam, sensitization on day 2 does not occur. Furthermore, although moderate (0.2 mg/kg) and high doses (0.5 mg/kg) of haloperidol (day 1) prevented the development of sensitization to cocaine, they were ineffective when given prior to the day 2 challenge dose in preventing the expression of sensitization. Thus, this type of cocaine sensitization appears to involve conditioning, show stimulus generalization, and offer a possible model for clinical neuroleptic nonresponsiveness once stimulant-induced pathological behavior has been induced.

Animals↗
PubMed1985

[Study of lever-holding phenomenon during the escape reaction in rats].

A "preparatory" hypothesis according to which the bar-holding develops as a preparatory response placing an animal in an advantageous position for the reaction on the subsequent action of the electric current has been experimentally examined. Comparing the avoidance training under the condition allowing the bar-holding until the next conditioned and unconditioned stimuli, and under conditions excepting such long holding it has been established that in first case the number of bar-holding responses is more and the avoidance responses are less than in the second one. It contradicts the "preparatory" hypothesis. It has been shown that the dynamics of inter-trail and the bar-holding responses results from stimulus generalization and discrimination.

Animals↗