共查询到20条相似文献，搜索用时 31 毫秒
1.
Two experiments with rats investigated learning about S+ and S? during various stages of discrimination training. Transfer tests, in which either S+ or S? was retained, or two new stimuli were presented, were used to assess learning early in acquisition, at criterion, or following overtraining. Both choice and latency measures were used. Results indicated that learning about S+ occurs early in acquisition when noncorrection training is given, and little improvement occurs after that time, at least up to 70 trials of overtraining under present conditions. Learning about S? begins somewhat later in acquisition and continues throughout overtraining. When correction training is used, learning about S? occurs earlier in acquisition, and further learning about both S+ and S? occurs during overtraining. 相似文献
2.
Steven J. Haggbloom 《Learning & behavior》1982,10(1):61-64
Three groups of 12 rats received 25 pretraining trials to each future discriminandum employed in a subsequent differential brightness conditioning problem. Groups NR and RN received partial reinforcement (PRF) pretraining either with or without, respectively, transitions from nonrewarded to rewarded trials (N-R transitions). Group CRF received consistent reinforcement during pretraining. A fourth group (n=12), Group NP, received no pretraining. During discrimination learning, one-half of the rats in each group received all their daily S+ trials preceding their daily S? trials (+? sequence); the remainder of the rats received an intermixed sequence of trials to S+ and S? (+?+ sequence). Discrimination learning was faster under the +? sequence than under the +?+ condition, and discrimination learning was retarded in Group NR relative to the other three groups, which did not differ from one another, under both the +? and +?+ discrimination sequence conditions. The results are discussed with Reference to previous experiments demonstrating N-R transition effects on discrimination learning, a theoretical extension of sequential theory to discrimination learning, and the effects of nondifferential reinforcement prior to discrimination learning on learned irrelevance. 相似文献
3.
William S. Maki 《Learning & behavior》1979,7(1):31-37
Pigeons performed a delayed matching-to-sample task in which they matched red and green disks as comparison stimuli to samples of food and no food. The birds were also taught a discrimination between two lines: vertical (S+) followed by food and horizontal (S?) followed by no food. The two kinds of trials were then chained in infrequent probes such that (a) S+ and S? preceded samples of food and no food, (b) a longer than usual delay occurred, and then, (c) the comparison stimuli were presented. Therefore, in probes when S+ preceded food and S? preceded no food, the samples were “expected. ” But in probes when S+ signaled no food and S? signaled food, the samples were “surprising. ” Matching to surprising samples was more accurate than matching to expected samples. This result completes a pattern of findings implying that surprising reinforcers enhance learning and also persist (are longer rehearsed) in short-term memory. 相似文献
4.
Steven J. Haggbloom 《Learning & behavior》1983,11(3):367-372
In two experiments, rats were trained on a successive go/no-go discrimination problem in the runway in which the positive (S+) and negative (S?) discriminanda were differentiated by the presence or absence of a distinctive feature. The feature in Experiment 1 was a series of flashing lights over the runway. In Experiment 2, the feature was a pretrial reinforcement (Phase 1), or pretrial reinforcement versus pretrial nonreinforcement (Phase 2). The feature signaled S+ trials in feature-positive (FP) groups and S? trials in feature-negative (FN) groups. The original discrimination was reversed in Phase 2 of both experiments. With the exception of the pretrial nonreinforcement groups in Experiment 2, there was an asymmetry in discrimination learning in both phases of both experiments favoring superior discrimination learning by FN subjects over FP subjects, a feature-negative effect. Implications of the results for an information processing account of asymmetries in learning feature discriminations are discussed. 相似文献
5.
Jacky Emmerton 《Learning & behavior》1998,26(3):243-256
Two experiments are described in which pigeons were trained in a simultaneous conditioning procedure to discriminate small arrays of dots that differed in numerosity. The birds successfully learned to choose the array of each pair that contained fewer dots when these choices were reinforced and choices of the array with more dots led to timeout. For the majority of numerosity values tested, discrimination performance for a fixed S+ value was better when the numerical difference between S+ and S-values was larger rather than smaller. This effect was seen in the first experiment when the numerical difference value was shifted between training trials and novel test trials. In the second experiment, too, performance level depended on the size of the numerosity difference when the birds were concurrently trained with two difference values that varied across trials within sessions. However, discrimination accuracy was influenced secondarily by variations in the density, or interdot spacing, of the stimulus arrays. In order to explain the latter finding, it is suggested that a tendency to “scan” a lowdensity array incompletely might alter the probability of accepting it as the smaller numerosity (S+) stimulus. This would increase error rates with S? arrays in which the dots are more widely spaced. 相似文献
6.
Steven J. Haggbloom 《Learning & behavior》1980,8(3):441-446
The effects of transitions from nonrewarded (N) to rewarded (R) trials (N-R transitions) on discriminative behavior in differential conditioning and subsequent resistance to extinction were investigated in two experiments. In Experiment 1, groups given N-R transitions within S+ were more resistant to discrimination (ran fast in S?) and extinction than were groups given a partial reinforcement (PRF) schedule in S+ devoid of N-R transitions. Experiment 2 indicated that N-R transitions that occur when an N trial in S? is followed by an R trial in S+ are as effective in increasing resistance to discrimination, but not resistance to extinction, as are N-R transitions that occur within S+. The sequential effects obtained here were highly similar to those in conventional PRF and support the view that differential conditioning and PRF are highly interrelated phenomena. The results are discussed in terms of the extension of sequential theory to differential conditioning and the importance of internal reward-produced cues in discrimination learning. 相似文献
7.
Steven J. Haggbloom 《Learning & behavior》1980,8(3):424-428
In two differential conditioning experiments, groups of 10 rats each differed with respect to average reward and schedule of reward received in S+. Nonreward (N) occurred on all S? trials. In both experiments, extinction of responding to S? (resistance to discrimination) was extensively regulated by reward sequence and was largely independent of average reward. In Experiment 1, resistance to discrimination was a function of transitions from N to rewarded (R) trials (N-R transitions). In Experiment 2, resistance to discrimination was increased by large reward on the R trial of N-R transitions and decreased by large reward on the R trial of R-N transitions. These schedule effects on resistance to discrimination parallel the effects of comparable schedules on resistance to extinction following partial reinforcement. The results are discussed in terms of sequential theory, reinforcement level theory, and their implications for various schedule manipulations that have previously shown S? behavior to be inversely related to average reward in S+. 相似文献
8.
Ruth M. Colwill 《Learning & behavior》1993,21(4):337-345
The effect of training a positive discriminative stimulus (S+ ) as a signal for the nonreinforcement of an instrumental response (S?) on the ability of that stimulus to evoke its original instrumental response was examined in three experiments using rats. In all three experiments, two different stimuli were established as S+s for different response-outcome relations. In Experiment 1, an S+ was less effective in controlling its original response after it had undergone training as an S? for a new response that earned the same outcome than it was after training as an S? for a response that earned a different outcome. Experiment 2 established that this effect was not mediated by Pavlovian inhibitory conditioning produced by the negative correlation between the S+ and the outcome during S? training. Simply arranging a negative correlation between S+ and the outcome whose occurrence it had previously signaled did not impair the ability of that S+ to elicit its original response. In Experiment 3, the response-evoking properties of an S+ were found to be undermined by using the S+ as a signal for the simple extinction of a new response trained with the same outcome, but not with a different outcome. These results suggest that positive discriminative stimuli use their associations with the outcomes earned in their presence to control the responses that earned those outcomes. 相似文献
9.
Discrimination performance was investigated with pigeons using feature negative (FN) discrimination procedures which differed in the temporal arrangement of the stimuli on S? trials. In both procedures, a single common element was presented on reinforced (S+) trials. In thesimultaneous FN procedure, a distinguishing element was presented simultaneously with the common element of S? trials. In thesequential FN procedure, the distinguishing element preceded onset of the common element on S? trials. In two experiments, the sequential FN procedure yielded better discrimination performance. In Experiment 1, a summation test designed to separate learning and performance variables indicated that sequential FN subjects had learned the negative relationship between the distinguishing element and reinforcement while simultaneous FN subjects had not. In Experiment 2, summation and acquisition tests indicated that the distinguishing element developed inhibitory properties in the sequential FN procedure but not in the simultaneous FN procedure. 相似文献
10.
Goldfish trained to discriminate between signals paired with shock (S?) and signals paired with shock omission (S+) with a linear presentation procedure, originally learned (OL) to control the signal state of a shuttle box and showed a decided preference for the S+ signal. In Experiment 1, following OL, groups had one OL signal replaced (S+ or S?), both signals replaced (S+ and S?), or the OL signals reversed (S+ and S? reversed) and were then tested in a transfer training procedure. In transfer, groups with one signal replaced maintained discriminated performance at OL levels; the S+ replaced group was slightly superior to the S? replaced group on the first day of transfer. With both OL signals replaced, discrimination dropped to chance performance levels, whereas, with OL signal shock pairing reversed, discrimination performance dropped below chance levels. In Experiment 2, following OL, extinction procedures consisted of turning off the shocker (0% shock) or of shocking 100% or a random 25% of the trials. A fourth extinction procedure (R,) retained the trial start response-dependent shock-omission contingency, but shock differentiating the S+ and S? signals was eliminated entirely. Extinction of the S+/S? discrimination was measured both during extinction training per se and with reversal retraining of the S+/S? discrimination later. Groups for which the OL S+ was paired with shock during extinction extinguished on both measures, but groups for which the OL S? was paired with shock omission did not extinguish, especially as shown by the reversal test procedure. Theoretical implications and the implications for several conditioning procedures are discussed. 相似文献
11.
Pigeons were given successive discrimination training in which pecking during a choice period when the key was white was either reinforced or not, depending upon the prior presence or absence of a discriminative stimulus, which was a two-element serial compound. The compound consisted of a keylight and food, with food presented second or first in a forward or backward pairing for different groups of pigeons. In Experiment 1, the sequence was an S+ indicating reinforced trials, while in Experiment 2, the sequence was an S? indicating nonreinforced trials. Following acquisition of discriminated operant behavior, a sequence generalization test was administered during which all possible orders of the two stimuli were presented on test trials prior to the onset of the choice period. The results showed that food overshadowed stimulus control by the color of the light on the key on the sequence-generalization test, independently of whether food was presented first or second during training and independently of whether food was associated with reinforcement or nonreinforcement. The similarity of results for the two experiments suggests that overshadowing occurs independently of whether the compound is a discriminative stimulus for reinforcement or nonreinforcement. Simultaneous presentation of elements of a compound stimulus is not necessary for overshadowing because the phenomenon was captured with sequentially presented stimuli. 相似文献
12.
Richard M. Wielkiewicz 《Learning & behavior》1979,7(2):246-250
Forty-eight albino rats were first exposed to randomly intermixed, noncontingent presentations of one pellet, six pellets, and water. For each of three groups, a CS+ was paired with one of the reinforcers, while the other two reinforcers and a CS? were presented alone. Then half the subjects experienced a six-pellet reward and half experienced a one-pellet reward for leverpresses during a light SD. Finally, on test trials, the CS+ or CS? was compounded with the light. Latencies on test trials indicated that responding for the one-pellet reward was significantly more disrupted by a CS+ for six pellets than by the CS+ for one pellet or the CS+ for water. Responding for the six-pellet reward was disrupted by the CS+ for one pellet somewhat more than by the CS+ for six pellets or water, but not significantly so. This pattern of results is partially consistent with an associative model of transfer and appears to contradict a motivational account of such effects. 相似文献
13.
Rhesus monkeys were trained to press panels to escape or avoid shock. Escape and avoidance training were combined factorially with feature-positive (FP) and feature-negative (FN) discriminations. In the FP situation, S+ trials were characterized by one red and two green panel displays and S? consisted of an all green panel array. In the FN arrangement, S+ and S? arrays were reversed. When compared properly, FP discriminations were learned more readily than FN discriminations in both escape and avoidance training conditions. Positive tracking was associated with FP discriminations, and feature avoidance characterized the FN tasks. These data suggest that in primates, feature responses (i.e., tracking behaviors) are more a function of the operant contingency than of the Pavlovian correlation. 相似文献
14.
Pigeons were reinforced for pecking a key following one signal duration (S+) but not following another signal duration (S?). The S+ and S? were 2.52 and 5.67 sec, respectively, counterbalanced across birds. Subsequent generalization tests with a range of signal durations revealed a step function, with high response rates for all durations on the S+ side of the distribution, low response rates for all durations on the S? side, and an intermediate rate for the intermediate duration. A comparison group of pigeons trained with only the S+ duration showed a flat generalization function. For the discrimination-trained birds, the delay between signal termination and opportunity to respond was subsequently varied during generalization testing. A step function again appeared, and no evidence of subjective shortening over the delay was found. The overall pattern of results suggests that the birds categorized the temporal signal into two classes and retained a categorical code over the delay. 相似文献
15.
Previous work has shown that when a delay of reward (DOR) is introduced into a well-learned discrimination, even gradually, discriminative performance deteriorates and, with moderately long DORs, does not recover with practice. The present experiment assessed whether the decrement in performance was due to an associative loss or to a decline in the incentive value of the reward object caused by the DOR. Cebus monkeys were trained on a simple visual discrimination and tested with either a DOR or an identical delay period which preceded the appearance of S+ and S? (“predelay” trials); reinforcement on predelay trials was immediate. On half of the daily trials, the animals were given the option of choosing either the DOR or the predelay trial. The duration of the delay was increased gradually until terminal delays of 32 to 128 sec were reached. All four animals maintained almost errorless performance on predelay trials; in contrast, their error rate reached 36% on DOR trials. Surprisingly, none of the animals learned to choose predelay over DOR trials. Both results were interpreted in terms of the incentive loss hypothesis. 相似文献
16.
Rats were trained in a light ON vs light OFF discrimination in operant chambers with food reinforcement. Following acquisition, extinction under conditions of no alternations between S+ and S? and under conditions of numerous alternations between S+ and S? were examined. In Experiment I, extinction in S+ or S? alone produced less responding to S+ and more responding to S? than extinction with regular alternations between S+ and S?. In Experiment II, 9, 39, or 79 alternations in extinction between S+ and S? produced no differences in responding. These results indicate that during extinction of a discrimination there is (a) sharpening of differential performance, (b) a difference between multiple- and single-stimulus procedures, and (c) little effect of different numbers of alternations. 相似文献
17.
In two experiments, we investigated the impact of odor preexposure treatments on the acquisition of an olfactory discrimination in dogs. In the first experiment, four groups of dogs were each given five days’ odor-exposure treatment prior to discrimination training. Dogs in the exposure group were exposed to anise extract (S+) for 30 min daily. Dogs in the Pavlovian-relevant pairing group received six daily delayed-conditioning trials to the same S+. The Pavlovian-irrelevant pairing group received conditioning trials to almond extract (S'). Dogs in the control group received no pretreatment. All of the dogs were then trained to detect S+ from a background pine odor (an AX-vs.-X discrimination). The Pavlovian-relevant pairing group acquired the odor discrimination significantly faster than all of the other exposure and control groups, and the remaining groups acquired the discrimination at the same rate as the no-exposure control group. In a second experiment, we extended these results to a within-subjects design using an AX-versus-BX discrimination. Six dogs were simultaneously trained on two different odor discriminations, one discrimination in which the S+ was previously Pavlovian conditioned, and one discrimination in which the S+ was novel. All of the dogs learned the odor discrimination with the previously conditioned S+ faster than they learned the novel odor discrimination, replicating the results of Experiment 1, and demonstrating that familiarity in the form of Pavlovian conditioning enhances odor-discrimination training. The potential mechanisms of the facilitated transfer of a Pavlovian conditioned stimulus to discrimination training are discussed. 相似文献
18.
A. P. Greenway 《Learning & behavior》1975,3(3):235-238
In a discrete trials multiple reversal experiment with singly presented stimuli, rats were given either 10 or 20 training trials per day for 2 days on each problem. All subjects improved progressively over reversals, but subjects with more training on each problem showed greater inhibition of responding to S? during reversal than those having less training. For both groups, the S? within sessions curve became steeper over reversals. Inhibition of responding to S? was greater on Day 2 of a reversal than on Day 1. The rat data are discussed in relation to those obtained from pigeons and goldfish. 相似文献
19.
Four experiments with rats tested their ability to anticipate serial patterns made from elements of reward magnitudes (14, 7, 3, 1, or 0 food pellets). Anticipation was measured by the running time in a straight alley. Elements arranged in a monotonically descending pattern were more easily anticipated than were the same elements arranged in a nonmonotonic pattern. Better anticipation was also observed when training utilized four trials per day with short interrun intervals (10–15 sec), spent in the startbox of the runway, than when training utilized one trial per day with long interrun intervals (4–5 min), spent in the rat’s home cage. Anticipation of the monotonie sequence was also superior when training consisted of one trial per day with a short interrun interval relative to that observed with four trials per day and a long interrun interval. Following acquisition of anticipation of the monotonie sequence with a short interrun interval, transfer to the same sequence with a long interrun interval resulted in disruption of anticipation. Finally, anticipation of a well-learned monotonie sequence was not disrupted by replacement of individual rewarded elements in the sequence with a 0-pellet element. These experiments indicate that the duration between runs of a trial, but not that between trials or the number of trials per day, is important in the formation of serial expectancies. They also suggest that the rats come to represent the sequence as items in serial position. 相似文献
20.
In conditioned suppression discriminations, the Konorski-Lawicka paradigm involves A+ trials, where conditioned stimulus A is followed by shock, and sh → A? trials, where A is preceded by shock Rats easily mastered this A+/sh → A? discrimination, as indicated by suppression of food-reinforced barpressing on A+ trials and acceleration of barpressing on sh → A? trials. A history of A+ conditioning resulted in nearly perfect discrimination performance on the very first day of A+/sh → A ? training, but a history of sh→ A? conditioning retarded development of the discrimination. The basis for the development of the discrimination was discussed in terms of an inferred stimulus (sh′) arising from the aftereffects of shock. 相似文献