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Results for “Generalization, Stimulus”

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PubMed1993

The effects of "do", "don't" and "wait" requests training on compliance behavior and stimulus generalization.

Previous implementation of compliance training has involved the use of aversive behaviors, as consequents, which bear neither a topographical nor a functional relationship to the behaviors under training. The present study explores compliance training in which training behaviors, used as consequents, are both topographically and functionally identical to the target behaviors. This study extends the compliance literature through: (1) an analysis of the effects of compliance training in long-term institutionalized mentally retarded adults, (2) the investigation of a third response class "Wait" requests, and (3) an assessment of stimulus generalization. Findings discussed include (a) the treatment effects of compliance training, across response classes, within treatment sessions; (b) the spontaneous generalization of treatment effects outside the treatment conditions; (c) the collateral effects of training upon aggressive outbursts; (d) the heightened potential for the utilization of these techniques in long-term care institutions.

Adult↗

PubMed1998

Effects of variable-interval value and amount of training on stimulus generalization.

In Experiment 1 pigeons pecked a key that was illuminated with a 501-nm light and obtained food by doing so according to a variable-interval (VI) schedule of reinforcement, the mean value of which differed across groups: either 30 s, 120 s, or 240 s. The pigeons in all three groups were trained for 10 50-min sessions. Generalization testing was conducted in extinction with different wavelengths of light. Absolute and relative generalization gradients were similar in shape for the three groups. Experiment 2 was a systematic replication of Experiment 1 using line orientation as the stimulus dimension and a mean VI value of either 30 s or 240 s. Again, gradients of generalization were similar for the two groups. In Experiment 3 pigeons pecked a key that was illuminated with a 501-nm light and obtained food reinforcers according to either a VI 30-s or a 240-s schedule. Training continued until response rates stabilized (> 30 sessions). For subjects trained with the 30-s schedule, generalization gradients were virtually identical regardless of whether training was for 10 sessions (Experiment 1) or until response rates stabilized. For subjects trained with the VI 240-s schedule, absolute generalization gradients for subjects trained to stability were displaced upward relative to gradients for subjects trained for only 10 sessions (Experiment 1), and relative generalization gradients were slightly flatter. These results indicate that the shape of a generalization gradient does not necessarily depend on the rate of reinforcement during 10-session single-stimulus training but that the effects of prolonged training on stimulus generalization may be schedule dependent.

Analysis of Variance↗

PubMed1985

Visual discrimination learning in mentally handicapped adults: comparative effects of two-choice and multiple-choice training methods on stimulus generalization performance.

The hypothesis that in mentally handicapped subjects a multi-choice discrimination learning method would result in superior generalization performance to the traditional two-choice method was investigated experimentally. Twenty-four mentally handicapped adults matched for age, intelligence and duration of institutionalization were divided into two equal groups and given visual discrimination training using a differential reinforcement, prompt-fading procedure. The groups were allocated separately to a two-choice and four-choice training condition in which the discriminative stimulus was associated with one and three non-discriminative stimuli respectively. Following training, stimulus discrimination performance was compared on a generalization test comprising increasing levels of distraction. The results showed a clear advantage for multi-choice training over two-choice. However, it was found that during generalization testing discriminative performance deteriorated as a function of increasing distraction in both groups, suggesting an underlying selective attention defect. Such a defect may be characteristic of stimulus generalization performance in the mentally retarded. Multi-choice discrimination learning appeared partly to counteract major generalization failure when the ratio of non-discriminative to discriminative stimuli was high.

Adult↗

PubMedDate not supplied

Cocaine--stimulus generalization to MDA optical isomers: a reevaluation.

It has already been demonstrated that the psychoactive agent 1-(3,4-methylenedioxyphenyl)-2-aminopropane (MDA) produces effects that are both hallucinogen-like and amphetamine or stimulant-like in animals. Hallucinogenic activity is associated primarily with the R(-)-isomer of MDA whereas stimulant activity is primarily associated with the S(+)-isomer. Because a previous report indicates that S(+)MDA fails to substitute for cocaine in rats trained to discriminate cocaine from vehicle, and because these findings are inconsistent with the purported stimulant nature of S(+)MDA, we reinvestigated the effect of both MDA isomers in rats. In this investigation, S(+)MDA doses of 1.25 and 1.5 mg/kg were found to produce > 80% cocaine-appropriate responding in rats trained to discriminate 8 mg/kg of cocaine from saline. However, consistent with a previous report, R(-)MDA resulted only in partial generalization. These new results support the hypothesis that the optical isomers of MDA produce distinguishable stimulus effects in rats and that S(+)MDA is the more stimulant isomer of MDA.

3,4-Methylenedioxyamphetamine↗

PubMed1984

Assessment of drug state dimensionality via drug-drug training and stimulus generalization testing.

A procedure for determining whether different drugs share a common stimulus dimension is described. This procedure uses the presence of post-discrimination generalization gradient asymmetry as an indication that the training stimuli lay along a common stimulus dimension. Separate groups of hungry pigeons were trained to discriminate a 15 mg/kg dose of phenobarbital which was associated with frequent food reinforcement (S+) from each of 9 different drug conditions which were associated with infrequent reinforcement (S-). S- stimuli were selected to represent a drug from a completely different class (amphetamine), a drug with biphasic effects which may partially correspond with the effects of phenobarbital (delta 9-THC), and a drug from the same class as the S+ (pentobarbital). Following discrimination training subjects were tested for generalization to five dosage levels (5, 10, 15, 20, 25 mg/kg) of phenobarbital. Steep symmetrical generalization gradients around the S+ indicated that delta 9-THC and d-1-amphetamine were both quite discriminable from phenobarbital, and that they were perceived by subjects as representing stimulus dimensions different from phenobarbital, and that it was perceived as lying on a stimulus dimension common to phenobarbital. This procedure may allow better understanding of how different drug states are perceived by animals as similar or dissimilar.

Amphetamines↗

PubMed1971

On the form of stimulus generalization curves for visual intensity.

Twelve pigeons were given successive discrimination training involving variable-interval reinforcement for key pecking in the presence of one intensity of monochromatic light randomly alternated with extinction for pecking during another intensity. All of the pigeons were then tested in extinction for generalization along the intensity dimension, and all showed a displacement of maximal responding from the positive stimulus in the direction opposite the negative stimulus. For six of the pigeons, for which the test included only three values beyond the positive stimulus, four showed peaked gradients but two did not, showing monotonic gradients with maximal responding to the most extreme test value. For another six pigeons tested over a wider range, all showed peaked gradients. Thus, when a sufficiently wide range of test values is employed, generalization gradients for visual intensity have the same peaked form as do gradients for qualitative visual dimensions such as wavelength or line angle.

Animals↗

PubMed1989

A role for stimulus generalization in conditional discrimination learning.

In each of three experiments on discrimination learning by rats, whether or not a 10-sec target stimulus was followed by food was determined by the nature of a 2-min background stimulus that accompanied it. A conditional discrimination was employed in Experiment 1 such that background A indicated food would follow one target but not the other, whereas this relationship between the targets and food was reversed in the presence of background B. Experiment 2 employed two feature-positive discriminations. Subsequent test trials revealed that the background for one discrimination was able to enhance responding during the target for the other discrimination. Experiment 3 employed a feature-positive and a feature-negative discrimination prior to test trials in which each target was presented separately during a compound of both background stimuli. The compound enhanced responding to the target from the feature-positive discrimination and reduced it to the target from the feature-negative discrimination. We suggest that to accommodate all these findings, the best explanation is provided by a configural model of Pavlovian conditioning.

Animals↗

PubMed1997

Stimulus generalization of fear responses: effects of auditory cortex lesions in a computational model and in rats.

The conditioning of fear responses to a simple acoustic stimulus (pure tone) paired with footshock can be mediated by the transmission of auditory information to the lateral nucleus of the amygdala from either the auditory thalamus or the auditory cortex. We examined the processing capacity of the thalamo-amygdala pathway by making lesions of the auditory cortex and testing the extent to which conditioned fear responses generalized to tones other than the one paired with footshock. Two studies were performed, one in an anatomically constrained computational model of the fear conditioning network and the other in rats. Stimulus generalization was unaffected in both. These findings support the validity of the model as an approach to studying the neural basis of conditioned fear learning, and in addition suggest that the thalamo-amygdala pathway, possibly by the use of population coding, is capable of performing at least crude stimulus discriminations.

Acoustic Stimulation↗

PubMed1969

Stimulus generalization of gravity.

In two experiments, squirrel monkeys were exposed to centrifugally generated, artificial gravity and trained to respond for food reinforcement at selected gravity (g) levels. Experiment I involved a single g value; in Exp. II, subjects were trained to discriminate among two or three g values. After training, generalization tests were administered over a 1.1-g to 2.1-g range. The major findings were as follows: (a) single-stimulus training yielded a linear relationship between percentage of responding and magnitude of gravity. (b) Two-valued discrimination training produced gradient peaks which were shifted from S(D) in a direction away from S(Delta). This effect was cancelled when S(D) was located equidistant between two S(Delta) stimuli. (c) Gradient form was independent of the S(D)-S(Delta) difference, but related to continuum location and/or intensity of discriminative stimuli.

Animals↗

PubMed1967

Stimulus generalization as signal detection in pigeons.

Pigeons that were reinforced for pecking at a single-wavelength responded to nearby wavelengths with lower rates. Response rates indicated the pigeons' certainty that the reinforced stimulus was present. The ratings yielded receiver operating characteristic functions that approximated straight lines on a double probability plot.

Animals↗

PubMed1978

The central tendency effect in stimulus generalization: the effect of sex of subject.

Eighty male and 80 female college students were shown a stimulus light of 525 nm, following instructions to remember it, and then were immediately tested for generalization (recognition) with a successively presented set of stimuli including 525 nm and six longer wavelength values. Subjects rated each test stimulus on a 6-point scale ranging from "surely same" as the original stimulus to "surely different." Both men and women showed a central tendency shift. Although the stimulus perceived as most likely to be the original (the mode) shifted to 545 nm in both groups, the men showed a greater mean shift than the women. Shifting was nearly complete in both groups within the first series of test stimuli with the men shifting faster. These findings replicate a 1972 report by Giurintano of greater central tendency shift in men than in women in a line angle generalization task, challenging an assumed analogy between our generalization task and the rod-and-frame test, in which women typically show the greater distortion. The analysis of central tendency shift within the first test series reveals that it occurs much earlier than previously believed.

Discrimination, Psychological↗

PubMed1982

Stimulus generalization of lifted weights in older and younger women.

Older (62 to 86 years) and younger (17 to 30 years) women were essentially similar in acquisition of weight discriminations and in generalized responding to a range of weights during postdiscrimination tests. In both age groups, acquisition was facilitated by increases in the difference between the positive and negative stimuli, and postdiscrimination gradients were displaced away from the value of the negative stimulus, particularly when it was the heavier of the training pair. The finding from personality test scores that the older women were more introverted than the younger ones, together with the absence of age differences in acquisition and generalization, does not support the Eysenck-Gray hypothesis that introversion influences conditioning processes. The results do suggest that basic conditioning processes are maintained with increasing age in healthy older adults.

Adolescent↗

PubMed1994

Electrical stimulation of the dorsal raphe nucleus as a discriminative stimulus: generalization to (+/-)-DOI.

Electrical stimulation of the dorsal raphe nucleus of Sprague-Dawley rats was used as the cue for discrimination using a taste aversion paradigm. Rats were trained to associate saccharin drinking during electrical stimulation of the dorsal raphe nucleus with LiCl injection after the session as the aversive unconditioned stimulus. In sessions without stimulation, rats were allowed to consume saccharin and received a saline injection after the session. Suppression of saccharin consumption during electrical stimulation was learned within 12 trials. Rats trained in the reverse discrimination, i.e., sessions with no electrical stimulation paired with LiCl injection, showed a similar learning curve. Animals injected prior to the session with the hallucinogenic 5-HT2 agonist (+/-)-DOI associated DOI with electrical stimulation of the dorsal raphe nucleus. Thus, animals may be trained to discriminate electrical stimulation of the dorsal raphe nucleus. Furthermore, animals generalize from activation of 5-HT2 receptors to electrical stimulation of the dorsal raphe nucleus.

Amphetamines↗

PubMed1988

Limited stimulus generalization between delta 9-THC and diazepam in pigeons and gerbils.

Pigeons trained to discriminate between the presence and absence of delta 9-THC (0.56 mg/kg, IM, intramuscularly) were tested with diazepam (5.6-30 mg/kg), administered IG (intragastrically), and were found to generalize the response associated with the THC training to the diazepam treatment only to a limited extent. Two groups of gerbils trained to discriminate between the presence and absence of IP (intraperitoneally) injected benzodiazepine agonists (5.6 mg/kg of diazepam and Ro 11-3128, respectively) generally did not generalize the drug response to IP administered THC (5.6 and 17.5 mg/kg). In addition, substitution testing with the dopamine autoreceptor blocker (+)-3PPP yielded non-drug responding in the pigeons. Hence neither proposed structural similarity between 3-PPP and THC, nor purported anxiolytic activity by 3-PPP (see Introduction) matched the THC-induced stimulus effects. The data are discussed with reference to the specificity of the THC cue or stimulus.

Animals↗

PubMed1966

Stimulus generalization: the ordering and spacing of test stimuli.

Twenty-four pigeons learned a successive discrimination between 500 mmu (S+) and 574 mmu (S-). When tested in extinction, some birds received stimuli around S+, with no S- presentations. These birds showed a positive peak shift, with maximum responding not at 550 mmu, but displaced to 538 mmu and 544 mmu. Other birds were tested with stimuli around S-, with no S+ presentations. These birds showed a negative shift, with least responding not at 574 mmu, but at 586 mmu. Though the first group was tested around S+ and the second around S-, total responding between groups did not differ. When retested on the other half of the continuum, however, birds that had gone from the S+ half to the S- half responded fewer times than those that had gone from the S- half to the S+ half. In a second experiment, reducing stimulus spacing from 6 mmu to 2 mmu produced flatter gradients and decreased the amount of positive shift. In a third experiment, birds were tested across the whole continuum with stimuli presented in serial order. A sequence from 538 mmu to 586 mmu produced no responding after the first part of the session; a sequence from 586 mmu to 538 mmu produced responding throughout the session.

Animals↗

PubMed1975

Stimulus generalization of suppression in rats following aversively motivated instrumental or Pavlovian training.

Following 100 or 300 avoidance training trials, instrumental subjects and their yoked Pavlovian counterparts were tested for generalization of lick suppression along the frequency dimension of the avoidance conditioned stimulus. Gradients of stimulus control were evident after 300 instrumental avoidance training trials, and additional intradimensional Pavlovian discrimination training further sharpened the gradients. After 100 trials, the yoked Pavlovian subjects suppressed more than their instrumental counterparts. However, with increased Pavlovian training, flatter gradients with decreased suppression were obtained. Results from a second experiment revealed that, whereas Pavlovian experience decreased suppression to the tone, subjects suppressed drinking in the presence of static, environmental cues. Data from both experiments supported interpretations that stress the role of response control over environmental events.

Acoustic Stimulation↗

PubMed1982

Discriminative stimulus effects of pentobarbital in rhesus monkeys: tests of stimulus generalization and duration of action.

Rhesus monkeys were trained to emit 20 or 30 consecutive responses on one lever following an IM injection of pentobarbital (10 or 18 mg/kg) and the same number of consecutive responses on another lever following an injection of saline. The required number of correct consecutive responses in both cases resulted in food delivery. When responding was reliably under the control of the presession injection, the ability of a variety of other compounds to produce pentobarbital-appropriate responding was examined. Diazepam, clobazam, methohexital, pentobarbital, and phenobarbital, given 10 or 20 min before the session, produced dose-related pentobarbital-appropriate responding in each monkey. Ethylketazocine and dextromethorphan produced responding primarily on the saline-appropriate lever, whereas codeine, cyclazocine, dextrorphan, and ketamine resulted in responding that was, on the average, intermediate between that appropriate for pentobarbital and that appropriate for saline. When tested at various times after their injection, methohexital (3.2 mg/kg) and pentobarbital (10 mg/kg) produced pentobarbital-appropriate responding within 10 min. Barbital (56 mg/kg) resulted in pentobarbital-appropriate responding only if at least 1 h intervened between the injection and the experimental session. The discriminative effects of methohexital, pentobarbital, and barbital lasted approximately 20-60, 120-240, and 480-720 min, respectively. The time-course of the discriminative stimulus effects of barbiturates in the rhesus monkey appears to parallel closely other pharmacological actions of these compounds.

Animals↗

PubMed1999

Stimulus generalization, context change, and forgetting.

Forgetting is often attributed to retrieval failure caused by background contextual cues changing over time. However, generalization between stimuli may increase over time and make them increasingly interchangeable. If this effect occurs with contextual cues, it might cancel any effect of a changing context. The authors review the evidence and suggest a resolution of this paradox. Although generalization gradients can change over time, the effect is not always strong. Increased responding to nontarget stimuli is not often shown, and few studies have demonstrated such changes with contextual cues in a way that rules out other interpretations. Even this example of forgetting may be caused by retrieval failure. The physical contexts manipulated in learning and memory experiments themselves occur within a superordinate temporal context and can thus be forgotten with no inherent challenge to a context-change account of forgetting.

Animals↗