Search Results
Results 451 - 500 of 1381
< 5 6 7 8 9 10 11 12 13 14 15 >
Jitsumori M - - 1994
Monkeys (Macaca mulatta) were trained to discriminate between sets of artificial stimuli such as those used by Jitsumori (1993) for pigeons and humans. The stimuli were arrays of symbols differing along three two-valued (positive or negative) dimensions. The discrimination required was between polymorphous categories in which a positive stimulus was ...
Graham S - - 1994
This experiment examined the effect of destroying the 5-hydroxytryptaminergic (5HTergic) pathways on the acquisition and performance of discrimination between two brief time intervals. Rats that had received injections of 5,7-dihydroxytryptamine into the dorsal and median raphe nuclei, and sham-lesioned control rats were trained in a series of discrete trials to ...
Davis R E - - 1994
The blockade of learning of Pavlovian fear conditioning by the N-methyl-D-aspartic acid (NMDA)-receptor antagonist MK-801 was examined in 166 goldfish. In previously untrained fish, MK-801 blocked learning of a light-off or a tone conditioned stimulus (CS) paired with an electrical shock unconditioned stimulus (US). Pretraining on the light-off CS did ...
Stubbs D A - - 1994
Under a psychophysical trials procedure, pigeons were presented with a red light of one duration followed by a green light of a second duration. Eight geometrically spaced base durations were paired with one of four shorter and four longer durations as the alternate member of a duration pair, with different ...
Esteves F - - 1994
We examined the possibility of nonconscious associative learning in a context of skin conductance conditioning, using emotional facial expressions as stimuli. In the first experiment, subjects were conditioned to a backwardly masked angry face that was followed by electric shock, with a masked happy face as the nonreinforced stimulus. In ...
Bonardi C - - 1994
In 4 experiments an instrumental contingency between a response and a reinforcer was introduced in the presence of a discriminative stimulus. Then a discriminative inhibitor (S delta) was established that signaled that the instrumental contingency would no longer operate in the presence of that discriminative stimulus, so that the S ...
Reed P - - 1994
Three experiments examined the influence of a brief stimulus (a light) on the behavior of food-deprived rats whose lever pressing on tandem schedules comprising components of different schedule types resulted in food presentation. In Experiment 1, either a tandem variable-ratio variable-interval or a tandem variable-interval variable-ratio schedule was used. The ...
Elsmore T F - - 1994
In two experiments conducted in an eight-arm radial maze, food pellets were delivered when a photocell beam was broken at the end of each arm via a nose poke, according to either fixed-interval or random-interval schedules of reinforcement, with each arm providing a different frequency of reinforcement. The behavior of ...
McLean A P - - 1994
Behavioral contrast and response-ratio sensitivity to reinforcement were compared in multiple schedules in which components alternated strictly or according to a pseudorandom sequence. Average component durations in the two regimes were always 60 s, and order of presentation of component alternation regimes was counterbalanced across subjects. In Part 1, the ...
Rammsayer T H - - 1994
In Experiment 1, the proposition that duration discrimination of filled auditory intervals is based on temporal information rather than on energy-dependent cues was tested in 64 naive subjects. The subjects were presented with two auditory stimuli at different levels of intensity within one trial, and had to decide which of ...
Zentall T R - - 1994
Value transfer theory has been proposed to account for transitive inference effects (L. V. Fersen, C. D. L. Wynne, J. D. Delius, & J. E. R. Staddon, 1991), in which following training on 4 simultaneous discriminations (A+B-, B+C-, C+D-, D+E-) pigeons show a preference for B over D. According to ...
Williams B A - - 1994
McLean (1992) presented significant data showing that the occurrence of behavioral contrast in a multiple schedule was correlated with shifts in the frequency of reinforcers from a second source between components of the schedule, and interpreted his results as showing that contrast was due to changes in the degree of ...
Gormezano I - - 1994
We determined MDA's effects on: (a) conditioning of the rabbit's jaw movement response (JMR) (Experiment 1); and (b) nonassociative JMRs and unconditioned JMRs (Experiment 2). Rabbits were administered 3,4-methylenedioxyamphetamine (MDA; 0, 2, or 4 mg/kg) into the marginal ear vein 20-30 min prior to each of 10 daily sessions. Experiment ...
Zeiler M D - - 1994
The peak procedure was used to study temporal control in pigeons exposed to seven fixed-interval schedules ranging from 7.5 to 480 s. The focus was on behavior in individual intervals. Quantitative properties of temporal control depended on whether the aspect of behavior considered was initial pause duration, the point of ...
Baron A - - 1994
Fixed-interval performances of rats were described either in terms of the individual intervals of the session or in terms of a single average interval constructed for the entire session. Responding in the individual intervals usually followed break-and-run and single response patterns rather than the scalloped pattern that emerged when the ...
Lattal K A - - 1994
Male Siamese fighting fish, Betta splendens, swam through a ring in an aquarium, breaking a photocell beam and initiating an unsignaled, resetting delay interval. Following delays of 0 s, 10 s, or 25 s, a 15-s mirror presentation released an aggressive display by the fish. Swimming through the ring increased ...
Iwata B A - - 1994
This study describes the use of an operant methodology to assess functional relationships between self-injury and specific environmental events. The self-injurious behaviors of nine developmentally disabled subjects were observed during periods of brief, repeated exposure to a series of analogue conditions. Each condition differed along one or more of the ...
Omino T - - 1993
Pigeons were exposed to a concurrent-chains schedule in which a single variable-interval 30-s schedule was used in the initial links and fixed-time schedules were used in the terminal links. Three types of keylight conditions were used in the terminal links. In the first condition, different delays were associated with different ...
Palya W L - - 1993
The ability of stimuli correlated with successive periods in a fixed interfood interval to support a response that produced or removed them was examined using pigeons. The degree to which those correlated stimuli elicited directed key pecks was also obtained. Stimuli early in the interval functioned as negative reinforcers, and ...
Grondin S - - 1993
Experiments 1 and 2 compared, with a single-stimulus procedure, the discrimination of filled and empty intervals in both auditory and visual modalities. In Experiment 1, in which intervals were about 250 msec, the discrimination was superior with empty intervals in both modalities. In Experiment 2, with intervals lasting about 50 ...
Voss P - - 1993
The present study compared the performance of 6 pigeons trained to detect luminance differences in two different signal-detection procedures. Exposed to a three-key array, the pigeons were trained to peck the left key when the brighter of two light intensities had been presented on the center key and to peck ...
McSweeney F K - - 1993
Pigeons pecked keys for food reinforcers delivered by multiple variable-interval 2-min variable-interval 2-min schedules. Positive behavioral contrast was created by changing one component to extinction; negative contrast was achieved by changing one component to a variable-interval 15-s schedule. The duration of each component was varied independently of the other from ...
Wyrwicka W - - 1993
This article reviews studies of various authors on the phenomenon of "switching," which is observed in both classical and instrumental conditioning and consists in elicitation of different responses to the same conditional stimulus (CS) when it is applied in an environment different than the original one. The different responses include ...
Panlilio L V - - 1993
Rats were trained to press a lever in the presence of a tone-light compound stimulus and not to press in its absence. In each of two experiments, schedules were designed to make the compound a conditioned punisher for one group and a conditioned reinforcer for the other. In Experiment 1, ...
Fantino E - - 1993
Delay-reduction theory states that the effectiveness of a stimulus as a conditioned reinforcer may be predicted most accurately by the reduction in time to primary reinforcement correlated with its onset. We review support for the theory and then discuss two new types of experiments that assess it. One compares models ...
Helmstetter F J - - 1993
Exposure to an innocuous stimulus that has been paired with footshock during Pavlovian conditioning results in the activation of descending antinociceptive systems in the rat. Several recent studies indicate that the hypoalgesia observed when contextual stimuli are paired with shock and the formalin test is used to measure antinociception depends ...
Iversen I H - - 1993
Steady and blinking white lights were projected on three nose keys arranged horizontally on one wall. The procedure was a conditional discrimination with a sample stimulus presented on the middle key and comparison stimuli on the side keys. Three rats acquired simultaneous "identity matching." Accuracy reached 80% in about 25 ...
Higa J J - - 1993
Recent developments reveal that animals can rapidly learn about intervals of time. We studied the nature of this fast-acting process in two experiments. In Experiment 1 pigeons were exposed to a modified fixed-time schedule, in which the time between food rewards (interfood interval) changed at an unpredictable point in each ...
Young A M - - 1993
Classical conditioning both to rewarding and to aversive stimuli is sensitive to drugs which act on the dopaminergic system: amphetamine enhances conditioning and neuroleptics attenuate it. Many lines of evidence point to the nucleus accumbens as being part of an anatomical substrate for reward. We have examined the release of ...
LeFrancois J R - - 1993
Bar presses by one group of rats were conditioned under a differential-reinforcement-of-low-rate reinforcement schedule immediately prior to conditioning under a fixed-interval schedule. In a second group of rats, bar presses were conditioned first under a differential-reinforcement-of-low-rate schedule and then under a fixed-ratio schedule prior to conditioning under a fixed-interval schedule. ...
Fetterman J G - - 1993
Pigeons were trained on a psychophysical choice task to discriminate between 2 fixed ratios and tested with probe ratios intermediate to the training requirements. Absolute and relative ratio size were varied over conditions. In a final condition, subjects were transferred from the number-based discrimination to a time-based discrimination. The times ...
Fredrikson M - - 1993
The reliability of classically conditioned skin conductance responses was investigated. Temporal stability was determined in 28 subjects studied three weeks apart (study 1), and internal consistency in 223 subjects studied once (study 2). A discriminative classical conditioning paradigm using slides with a duration of 8 s served as conditioned stimuli ...
Omino T - - 1993
In two experiments, pigeons were exposed to concurrent-chains schedules in which a single initial-link variable-interval schedule led to access to terminal links composed of fixed-interval or fixed-delay schedules. In Experiment 1, an 8-s (or 16-s) delay to reinforcement was associated with the standard key, while reinforcer delay values associated with ...
Leung J P - - 1993
College students responded for monetary rewards in two experiments on choice between differentially segmented aperiodic schedules of reinforcement. On a microcomputer, the concurrent chains were simulated as an air-defense video game in which subjects used two radars for detecting and destroying enemy aircraft. To earn more cash-exchangeable points, subjects had ...
Bouton M E - - 1993
Four experiments with rat subjects examined the effects of contextual conditioning on conditioned appetitive performance. Experiment 1 compared the effects of contextual conditioning on performance to conditioned stimuli (CSs) with different conditioning histories. Contextual conditioning enhanced performance to the CS if the CS had first been conditioned and then extinguished, ...
Crosbie J - - 1993
In two experiments a multiple-response repertoire of four free-operant responses was developed with university students as subjects using monetary gain as reinforcement. Following baseline, one of the responses was reduced either by making monetary loss contingent upon it (response cost) or by removing it from the repertoire (response restriction). In ...
Nevin J A - - 1993
In a discrete-trial conditional discrimination procedure, 4 pigeons obtained food reinforcers by pecking a key with a short latency on trials signaled by one stimulus and by pecking the same key with a long latency on trials signaled by a second stimulus. The physical difference between the two stimuli and ...
McLean A P - - 1992
Four pigeons responded in components of multiple schedules in which two responses were available and reinforced with food. Pecks on the left key ("main" key) were reinforced at a constant rate in one component and at a rate that varied over conditions in the other component. When reinforcer rate was ...
Davison M - - 1992
Six pigeons responded on two concurrently available keys that defined patches with the following characteristics. Reinforcer stores repleted on a patch as a linear function of time when the bird had last responded to the other patch, or else did not replete. Repletion schedules thus timed only when the bird ...
Lovibond P F - - 1992
Two experiments investigated phasic and tonic electrodermal responding to long, variable-duration stimuli in aversive conditioning procedures. Experiment I demonstrated reliable differential conditioning on both phasic (first interval response, FIR) and tonic (change in skin conductance level, delta SCL; spontaneous fluctuations) measures, using 10-40-s slides as conditioned stimuli (CSs) and electric ...
Courtney K - - 1992
Rats' presses on one lever canceled shocks programmed after variable cycles, while presses on a second lever occasionally produced a 2-min timout during which the shock-delection schedule was suspended and its correlated stimuli removed. These concurrent schedules of avoidance and timeout were embedded in a multiple schedule whose components differed, ...
Arbuckle J L - - 1992
In two experiments, key pecking of pigeons was maintained by a variable-interval 180-s schedule of food presentation. Conjointly, a second schedule delivered response-dependent electric shock. In the first experiment, shocks were presented according to either a variable-interval or a nondifferential interval-percentile schedule. The variable-interval shock schedule differentially delivered shocks following ...
Baron A - - 1992
Rats responded under progressive-ratio schedules for sweetened milk reinforcers; each session ended when responding ceased for 10 min. Experiment 1 varied the concentration of milk and the duration of postreinforcement timeouts. Postreinforcement pausing increased as a positively accelerated function of the size of the ratio, and the rate of increase ...
Williams B A - - 1992
Procedures used to study anticipatory contrast are conceptually similar to those used to study autoshaping, in that two target stimuli signal either higher or lower rates of reinforcement in the following components of the schedule. Despite this signal contingency, anticipatory contrast entails response rates that are higher to the target ...
Hanna E S - - 1992
Six experimentally naive pigeons were exposed to concurrent variable-interval variable-interval schedules in a three-key procedure in which food reinforcement followed pecks on the side keys and pecks on the center key served as changeover responses. In Phase 1, 3 birds were exposed to 20 combinations of five variable-interval values, with ...
Machado A - - 1992
In Experiment 1, two conditions were compared: (a) a variability schedule in which food reinforcement was delivered for the fourth peck in a sequence that differed from the preceding N four-peck sequences, with the value of N continuously adjusted to maintain reinforcement probability approximately constant; and (b) a control condition ...
White K G - - 1992
Two pigeons had access to multiple concurrent schedules of reinforcement for 24 hours per day in their home cages. The variable-interval schedules comprising the multiple concurrent schedules were varied across 16 conditions. In three sets of conditions, one schedule was varied while its concurrent alternative and the concurrent schedules in ...
Poling A - - 1992
Pigeons were exposed to delayed-matching-to-sample (DMTS) procedures in which food or a flash of the feeder light followed correct responses. When these consequences were correlated with a particular stimulus (e.g., food followed matching responses to red and a flash of the feeder light followed matching responses to green), accuracy was ...
Mauk M D - - 1992
This study demonstrates that individual animals can concurrently acquire differently timed conditioned eyelid responses using a differential conditioning procedure in which distinctive conditioned stimuli (CSs) are individually paired with an unconditioned stimulus, with each using a different interstimulus interval (ISI). This promotes robust conditioning, and the timing of the conditioned ...
Shull R L - - 1992
Pigeons chose between two fixed-interval schedules of food reinforcement. A single peck on one of two lighted keys started the fixed-interval schedule correlated with that key. The schedule had to be completed before the next choice opportunity. The durations of the fixed intervals were varied over conditions from 15 s ...
< 5 6 7 8 9 10 11 12 13 14 15 >