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Results 401 - 450 of 1381
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Slawecki C J - - 1997
Six male Long-Evans rats were trained to self-administer 10% ethanol (v/v) during 30 min operant sessions. A licking response on an empty drinking tube resulted in the presentation of reinforcement from an automatic dipper. During the initiation of ethanol self-administration, a tone-light stimulus complex was paired with all ethanol presentations. ...
Walker D L - - 1997
The amplitude of the acoustic startle response is reliably enhanced when elicited in the presence of bright light (light-enhanced startle) or in the presence of cues previously paired with shock (fear-potentiated startle). Light-enhanced startle appears to reflect an unconditioned response to an anxiogenic stimulus, whereas fear-potentiated startle reflects a conditioned ...
Dube W V - - 1997
Stimulus control was evaluated in 3 individuals with moderate to severe mental retardation by delayed identity matching-to-sample procedures that presented either one or two discrete forms as sample stimuli on each trial. On pretests, accuracy scores on one-sample trials were uniformly high. On two-sample trials, the correct stimulus (i.e., the ...
Shimura T - - 1997
The pontine parabrachial nucleus is considered to be one of the most critical regions for the acquisition of conditioned taste aversion which is an associative learning of taste and illness. To further clarify the possible involvement of the parabrachial nucleus in conditioned taste aversion, we recorded neuronal responses to taste ...
Neumann D L - - 1997
The present study aimed to demonstrate conditioned inhibition of Pavlovian conditioning of autonomic responses in humans. Subjects (N = 21) were presented initially with four geometric shapes (A, B, C and D). An electric shock served as the unconditioned stimulus (US) during acquisition. Conditional stimuli lasted for 8 s and ...
Ruob C - - 1997
If a stimulus (e.g. light) is repeatedly preexposed without consequences, it subsequently develops a weaker association with a reinforcer (e.g. foot shock) than does a non-preexposed stimulus. This retarded conditioning to the preexposed as compared to the non-preexposed stimulus, is latent inhibition (LI). It is well documented that LI is ...
Zeigler H P - - 1997
In nature, pecking involves the transport of a prehensile effector organ (the beak) towards biologically significant targets, and the generation jaw movement patterns whose probability and topography are appropriate to the stimulus properties of the target (e.g., distance, direction, size) and the motivational state of the animals (hunger, thirst). Because ...
Abramson C I - - 1997
Several series of experiments are reported that investigate learning in the Africanized honey bee. In the first series, classical conditioning of proboscis extension was studied by confining bees to small metal tubes where they received pairings of an odor with a 3-s feeding of sucrose. After a number of odor-sucrose ...
McClure G Y - - 1997
The effects of methamphetamine, phencyclidine and delta9-tetrahydrocannabinol on responding under temporal response differentiation schedules were studied under three different time requirements. Under the schedules studied, Sprague-Dawley rats were required to make a continuous response for at least a minimum time duration, but not more than a maximum. Baseline performance under ...
Falls W A - - 1997
Posttraining lesions of the perirhinal cortex (Prh) have been shown to interfere with the expression of fear. This study assessed whether Prh lesions would also disrupt the inhibition of fear as measured with conditioned inhibition of fear-potentiated startle. Following light + shock, noise-->light-no shock conditioned-inhibition training, rats were given Prh ...
Lejeune H - - 1997
Thirty rats received training on a peak-interval procedure, where a baseline with a 20-s time of reinforcement was interspersed among cyclic transitions to other reinforcement time values (10, 20, 30, or 40 s), each of which was either in force for only a single session or for 3 sessions. Peak ...
Gisquet-Verrier P - - 1997
To determine the contribution of the hippocampus in the processing of a configural positive patterning discrimination (PPD) task, discrimination between reinforced presentations of a tone plus light compound stimulus and nonreinforced presentations of each of its components (TL+/T-,L-) was examined using a conditioned-suppression paradigm. In the first experiment, rats demonstrated ...
Weiner I - - 1997
Latent inhibition (LI) refers to retarded conditioning to a stimulus that had been repeatedly preexposed without consequences, as compared with a nonpreexposed stimulus. Amphetamine disrupts LI, and this effect was suggested to result from enhanced switching to respond according to the stimulus-reinforcer contingency. Recently, it has been argued that amphetamine ...
Farley J - - 1997
Modifications of Hermissenda's phototactic behavior by compound pairings of light, scallop extract, and rotation were assessed. In general, the scallop extract potentiated phototactic suppression. Potentiation was dependent on (a) conjunctive presentations of scallop and light, (b) number of conditioning trials, and (c) scallop extract concentration. In related experiments, no second-order ...
Hunt P S - - 1997
Pairing an olfactory conditioned stimulus (CS) with an acoustic startle unconditioned stimulus (UCS) produced conditioned bradycardia in rats ranging from 12 days of age to adulthood but failed to produce conditioning in 10-day-olds (Experiment 1). The second experiment compared the effects of two different UCSs, acoustic startle and electric shock. ...
Letourneau E J - - 1997
The classical conditioning of subjective and physiological aspects of female sexual arousal was examined. Experimental subjects were run in a delayed conditioning design, where an amber light was paired with excerpts from erotic videos. Control subjects received presentations of the same amber light and videos, but these presentations did not ...
Wearden J H - - 1997
Normal adults were tested in eight temporal bisection conditions, using 500-Hz tones as stimuli. Stimulus lengths matched, or overlapped with, durations normally used in bisection experiments with animals, and chronometric counting was prevented by using a concurrent digit-shadowing task. Four experimental groups were used to investigate any effects of stimulus ...
Brandão M L - - 1997
The inferior colliculus has been implicated in aversive or anxiogenic aspects of defensive behavior. Animals learn to turn off electrical stimulation applied to the inferior colliculus. The purpose of the present study was to determine (1) whether this aversion induced by electrical stimulation can be conditioned to a conditioned stimulus ...
Kassel J D - - 1997
An accumulation of evidence suggests that smoking may be reinforcing, in part, due to nicotine's capacity to enhance attentional processing. Correspondingly, the stimulus-filter model of nicotine reinforcement asserts that nicotine facilitates cognitive performance by acting as a stimulus-barrier, thereby screening irrelevant and annoying stimuli from the smoker's awareness. A review ...
Uretsky M E - - 1996
The amphibian Xenopus laevis embryo (tadpole) provides a satisfactory alternative to mammalian screening for structural teratogens. Testing was undertaken to extend the usefulness of this species for behavioral teratogenicity testing. One simple and eight operant conditioning paradigms were examined: none elicited learning in Xenopus embryos. Adaptation to the conditioning stimulus ...
Lariviere N A - - 1996
Four experiments tested the effects in the rat of very early experience with stimuli to be used later for Pavlovian conditioning. Beginning on postnatal Day 12, prior to the development of substantial detection and effective perception of visual and auditory stimuli, rats were given five daily experiences with either lights ...
Weiss S J - - 1996
The dynamics of appetitive-aversive interaction theory were assayed in an experiment where excitors and inhibitors from the same and different incentive classes were compounded. Excitatory and inhibitory incentive properties acquired by the discriminative stimuli resulted from the reinforcement differences between components of four-component multiple training schedules, with the influence of ...
Leinenweber A - - 1996
Progressive-interval performances are described using measures that have proven to be successful in the analysis of fixed-interval responding. Five rats were trained with schedules in which the durations of consecutive intervals increased arithmetically as each interval was completed (either 6-s or 12-s steps for different subjects). The response patterns that ...
Akins C K - - 1996
In a trace conditioning procedure, subjects were presented with a 30-sec conditioned stimulus (CS) followed by a 30-sec trace interval. Delayed conditioning consisted of a 60-sec CS presentation followed by an unconditioned stimulus (US). Although conditioning developed with both procedures, the topography of the conditioned response differed. Sexual conditioned approach ...
Lam Y W - - 1996
Conditioned enhancement of the rat eyeblink reflex was studied using as a response measure the electromyogram (EMG) in the orbicularis oculi (oo) muscle, which is responsible for the active force generating eyelid closure. During a reflex eyeblink, the EMG evidences both a short-latency (R1) and a long-latency (R2) component, mediated ...
Zorina Z A - - 1996
A system of four to five differentiations forming a series, in which the magnitude of the reinforcement (R) of each succeeding color stimulus was greater than the preceding by one unit, was formed in pigeons (Columba livia L.) and crows (Corvus corone cornix L.). The number of units of the ...
Hatfield T - - 1996
Considerable evidence suggests that various discrete nuclei within the amygdala complex are critically involved in the assignment of emotional significance or value to events through associative learning. Much of this evidence comes from aversive conditioning procedures. For example, lesions of either basolateral amygdala (ABL) or the central nucleus (CN) interfere ...
Mongeluzi D L - - 1996
Four experiments were conducted to examine the utility of carbon dioxide (CO2) as an aversive unconditioned stimulus (US) in a Pavlovian context conditioning paradigm. Experiment 1 demonstrated that rats exposed to CO2 in a distinctive context showed elevated levels of freezing relative to controls. Experiment 2 replicated this basic effect ...
Panlilio L V - - 1996
Presenting independently established discriminative stimuli in compound can substantially increase response rates under food and shock-avoidance schedules. To determine whether this effect extends to drug self-administration, rats were trained to press a lever to receive cocaine intravenously. A tone and a light were independently established as discriminative stimuli for cocaine ...
Williams B A - - 1996
Pigeons were trained on a multiple schedule of reinforcement in which separate concurrent schedules occurred in each of two components. Key pecking was reinforced with milo. During one component, a variable-interval 40-s schedule was concurrent with a variable-interval 20-s schedule; during the other component, a variable-interval 40-s schedule was concurrent ...
Jones B M - - 1996
Five pigeons were trained on a concurrent-schedule analogue of the "some patches are empty" procedure. Two concurrently available alternatives were arranged on a single response key and were signaled by red and green keylights. A subject could travel between these alternatives by responding on a second yellow "switching" key. Following ...
Bitsios P - - 1996
It has been shown that the eye-blink response evoked by an abrupt loud white noise ('acoustic startle') is potentiated when the subjects anticipate an aversive stimulus, e.g. an electric shock ('fear-potentiated startle'). It has been proposed that this paradigm may be a useful laboratory model of human anxiety. We examined ...
Rogers R F - - 1996
Two important features of modern accounts of associative learning are (1) the capacity for contextual stimuli to serve as a signal for an unconditioned stimulus (US) and (2) the capacity for a previously conditioned (excitatory) stimulus to "block" learning about a redundant stimulus when both stimuli serve as a signal ...
McAdie T M - - 1996
Four hens worked under independent multiple concurrent variable-interval schedules with an overlaid aversive stimulus (sound of hens in a poultry shed at 100dBA) activated by the first peck on a key. The sound remained on until a response was made on the other key. The key that activated the sound ...
Kim S D - - 1996
Four experiments using barpress conditioned suppression in rats found that tone evoked more freezing (immobility) than did light. Still, tone and light appeared to have similar conditioned value as assessed by suppression in Experiments 1, 2, and 3, and by blocking, second-order conditioning, and overconditioning assays in Experiments 1, 2, ...
Fouriezos G G School of Psychology, University of Ottawa, Ontario, - - 1996
Rats implanted with lateral hypothalamic electrodes pressed a lever to obtain 0.5 s bursts of pulses under the four combinations of fixed or variable, interval or ratio, schedules of reinforcement. Along with continuous reinforcement schedules, intervals of 1, 2, 5, and 10 s, or ratios of 2, 5, and 10 ...
Heyman G M - - 1995
In two experiments deviations from matching earned higher overall reinforcement rates than did matching. In Experiment 1 response proportions were calculated over a 360-response moving average, updated with each response. Response proportions that differed from the nominal reinforcement proportions, by a criterion that was gradually increased, were eligible for reinforcement. ...
White K G - - 1995
In a successive discrimination, red and green hues signaled component variable-interval schedules. The exponent of the power function relating ratios of responses in the red and green components to ratios of reinforcers provided a reinforcement-free measure of discrimination or stimulus control. Responses were recorded in successive 10-s subintervals of the ...
Nordholm A F - - 1995
Linopirdine (DUP 996), a proposed cognitive enhancing agent, was studied in four squirrel monkeys (Saimiri sciureus) and six White Carneau pigeons responding under a titrating matching-to-sample paradigm (TMTS). Briefly, under this titration schedule, each trial began with the presentation of a sample stimulus on the center key of a three-key ...
Schmid A - - 1995
The acoustic startle response of rats was found to be attenuated if elicited in the presence of a conditioned stimulus predicting reward. During conditioning, animals received a total of 21 pairings of light with palatable food and sucrose solution, whereas controls received food and sucrose in the absence of light. ...
Pilgrim C - - 1995
Following the emergence of two four-member equivalence classes (A1B1C1D1 and A2B2C2D2), 5 students were exposed to a series of phases including a baseline conditional discrimination reversal (i.e., choosing D2 was reinforced and D1 punished given Sample A1; choosing D1 was reinforced and D2 punished given Sample A2), the delayed introduction ...
Armony J L - - 1995
Conditioning of fear reactions to an auditory conditioned stimulus (CS) paired with a footshock unconditioned stimulus (US) involves CS transmission to the amygdala from the auditory thalamus, the auditory cortex, or both. This article presents a simple neural network model of this neural system. The model consists of modules of ...
McLean A P - - 1995
Four pigeons responded on multiple schedules arranged on a "main" key in a two-key experimental chamber. A constant schedule component was alternated with another component that was varied over conditions. On an extra response key, conjoint schedules of reinforcement that operated in both components were arranged concurrently with the multiple ...
Alsop B - - 1995
Four experiments, each with 6 human subjects, varied the distribution of reinforcers for correct responses and the probability of sample-stimulus presentation in symbolic matching-to-sample procedures. Experiment 1 held the sample-stimulus probability constant and varied the ratio of reinforcers obtained for correct responses on the two alternatives across conditions. There was ...
Del Seppia C - - 1995
The comparison of two measurements of the pigeon threshold for electrical stimuli, performed 2 h apart, reveals stress-induced analgesia as a result of stressful manipulations between the two tests. When pigeons are exposed to a weak, oscillating magnetic field between the two measurements, the analgesic response is inhibited and a ...
Rogers W R - - 1995
Using a set of six baboons (Papio cynocephalus), we conducted a series of seven experiments designed to evaluate the potentially aversive character of a 60 Hz electric field (EF). Initially, the subjects were trained, using food rewards as the reinforcer, to respond only when a cue light was illuminated. Next, ...
Fetterman J G - - 1995
Pigeons partitioned time into three intervals. Responses to one key could be reinforced after a short time, to a second key after an intermediate time, and to a third key after a long time. The values of the short, intermediate, and long times and the proportion of trials ending with ...
Kiyatkin E A - - 1995
Although a large body of neuropharmacological evidence suggests that the mesolimbic dopamine system (ML DA) is critical for goal-directed behaviors, exactly which aspects of behavior are mediated or modulated by this system remains a matter of conjecture. By measuring changes in DA cell firing patterns and extracellular DA concentrations in ...
Kuno H - - 1994
Four homing pigeons were trained over 5 months in a zero-delay, "arbitrary" matching-to-sample procedure with sample and comparison stimuli presented on any of three response keys. Birds were also required to complete a fixed-ratio 10 requirement on both sample and comparison stimuli to terminate their presentation. The procedure resulted in ...
Dougher M J - - 1994
Two studies investigated the transfer of respondent elicitation through equivalence classes. In Experiment 1, match-to-sample procedures were used to teach 8 subjects two four-member equivalence classes. One member of one class was then paired with electric shock, and one member of the other class was presented without shock. All remaining ...
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