Stimulus-control factors in search performance of hyperactive children   总被引：1，自引：0，他引：1  

S S Zentall 《Journal of learning disabilities》1985,18(8):480-485

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Categorical color coding by pigeons     

Thomas R. Zentall  Charles A. Edwards 《Learning & behavior》1984,12(3):249-255

Pigeons were trained on two independent tasks. One involved red and yellow hues, the other involved blue and green hues. For half of the birds, the two tasks were the same (i.e., both tasks were either matching-to-sample, or oddity-from-sample). For the remaining birds, the two tasks were different (i.e., one task was matching-to-sample; the other task was oddity-from-sample). Following acquisition, the pigeons were exposed to test trials on which either the correct or the incorrect comparison hue was replaced with one of the hues from the other task. On yellow-sample trials and on green-sample trials, the pigeons performed as if they had a common code for yellow and green. When there was one comparison available that was appropriate to the “yellow/green” code, performance remained high; but when either both comparisons or neither comparison was appropriate to the “yellow/green” code, performance dropped. The pigeons also tended to code red samples as green and to code blue samples as yellow. The results indicate that pigeons can categorically code colors under conditions that rule out a failure to discriminate among the colors.  相似文献   

Midsession reversals with pigeons: visual versus spatial discriminations and the intertrial interval     

Jennifer R. Laude  Jessica P. Stagner  Rebecca Rayburn-Reeves  Thomas R. Zentall 《Learning & behavior》2014,42(1):40-46

Discrimination reversal learning has been used as a measure of species flexibility in dealing with changes in reinforcement contingency. In the simultaneous-discrimination, midsession-reversal task, one stimulus (S1) is correct for the first half of the session, and the other stimulus (S2) is correct for the second half. After training, pigeons show a curious pattern of choices: They begin to respond to S2 well before the reversal point (i.e., they make anticipatory errors), and they continue to respond to S1 well after the reversal (i.e., they make perseverative errors). That is, pigeons appear to be using the passage of time or the number of trials into the session as a cue to reverse, and are less sensitive to the feedback at the point of reversal. To determine whether the nature of the discrimination or a failure of memory for the stimulus chosen on the preceding trial contributed to the pigeons’ less-than-optimal performance, we manipulated the nature of the discrimination (spatial or visual) and the duration of the intertrial interval (5.0 or 1.5 s), in order to determine the conditions under which pigeons would show efficient reversal learning. The major finding was that only when the discrimination was spatial and the intertrial interval was short did the pigeons perform optimally.  相似文献   

Preference for rewards that follow greater effort and greater delay     

Alessandri J  Darcheville JC  Delevoye-Turrell Y  Zentall TR 《Learning & behavior》2008,36(4):352-358

Humans prefer (conditioned) rewards that follow greater effort (Aronson & Mills, 1959). This phenomenon can be interpreted as evidence for cognitive dissonance (or as justification of effort) but may also result from (1) the contrast between the relatively greater effort and the signal for reinforcement or (2) the delay reduction signaled by the conditioned reinforcer. In the present study, we examined the effect of prior force and prior time to produce stimuli associated with equal reinforcement. As expected, pressing with greater force or for a longer time was less preferred than pressing with less force or for a shorter time. However, participants preferred the conditioned reinforcer that followed greater force and more time. Furthermore, participants preferred a long duration with no force requirement over a shorter duration with a high force requirement and, consistent with the contrast account but not with the delay reduction account, they preferred the conditioned stimulus that followed the less preferred, shorter duration, high-force event. Within-trial contrast provides a more parsimonious account than justification of effort, and a more complete account than delay reduction.  相似文献   

Effect of a conspecific’s presence on deprived rats’ Performance: Social facilitation vs distraction/imitation     

John M. Levine  Thomas R. Zentall 《Learning & behavior》1974,2(2):119-122

The present study investigated effects of (a) conspecific’s “mere presence” and (b) water deprivation on emission of dominant responses by rats. Zajonc (1965) suggests that a conspecific’s presence functions like a physiologically based drive in enhancing performance of dominant responses. Alternative interpretations suggest that a conspecific’s presence impairs performance by distracting the observer or eliciting imitation of “irrelevant” responses. The social facilitation vs distraction/imitation hypotheses were tested in a 2 by 2 design: Barpress-trained rats, deprived of water for 4 or 23 h, barpressed for water in the presence of a naive rat or alone. Results supported social facilitation theory: Performance was significantly higher when the conspecific was present rather than absent and when the responder was 23 h rather than 4 h deprived. In reconciling these data with conflicting results, it was suggested that degree of contact may be important in determining how a conspecific’s presence affects performance of dominant responses.  相似文献   

Coding of feature and no-feature events by pigeons performing a delayed conditional discrimination     

Lou M. Sherburne  Thomas R. Zentall 《Learning & behavior》1993,21(2):92-100

Pigeons’ performance of a delayed conditional discrimination with presence versus absence of conditional (sample) stimuli was examined in two experiments. The pigeons showed steeper retention functions with feature (i.e., presence) samples (either food or yellow) than with no-feature (i.e., absence) samples (either no food or no yellow). These results suggest that pigeons code features and respond only by default to test stimuli (comparisons) associated with no features. In contrast, the overall superiority of performance on no-feature-sample trials compared with feature-sample trials in both the food/no-food- and yellow/no-yellow-sample tasks was reversed at a 0-sec delay in the food/no-food-sample group, but not in the yellow/non-yellow-sample group. This difference in results with hedonic versus nonhedonic samples suggests that the crossover in delay performance on food/no-food-sample trials is produced by the formation of backward associations between the food-associated comparison stimulus and the food sample.  相似文献   

Interaction of sample dimension and sample-comparison mapping on pigeons’ performance of delayed conditional discriminations     

Thomas R. Zentall  Peter J. Urcuioli  Joyce A. Jagielo  Pamela Jackson-Smith 《Learning & behavior》1989,17(2):172-178

Coding strategies developed in the acquisition of delayed conditional discriminations can be assessed by independently manipulating sample and comparison memory load. Two stimulus dimensions that can affect memory load were examined: Number of stimuli in the sample and comparison sets (two vs. four) was manipulated between groups in a 2×2 design, and discriminability of sample and comparison stimuli (hues vs. lines) was manipulated between counterbalancing subgroups and within subjects. The results indicated large effects of sample discriminability but not of comparison discriminability, evidence for retrospective coding. There was also a significant effect of number of stimuli in the comparison set (although only with hard-to-discriminate samples) but not of number of stimuli in the sample set, evidence for prospective coding. These findings suggest evidence for retrospective coding with easy-to-discriminate samples, independently of number of stimuli in the comparison set, and evidence for prospective coding with hard-to-discriminate samples.  相似文献   

“Same/different” symbol use by pigeons     

Charles A. Edwards  Joyce A. Jagielo  Thomas R. Zentall 《Learning & behavior》1983,11(3):349-355

Pigeons learned to respond at one spatial position when a pair of stimuli matched and at a different spatial position when they mismatched. All birds were then transferred to novel stimuli on an orthogonal dimension. For the positive-transfer group, the correct positions for matching and mismatching stimuli remained as they were during training. For the negative-transfer group, the correct positions were reversed. In Experiment 1, the birds were trained with shape stimuli and transferred to hue stimuli. Significant group differences were found, in spite of considerable stimulus-specific learning. In Experiment 2, when the same birds (counterbalanced for Experiment 1 transfer group) were transferred to steady-intermittent stimuli, even larger group differences were found. The data indicate that pigeons have some capacity for representing the concepts “same” and “different” with arbitrary stimuli (i.e., symbols). The data further suggest that distinctions that have been made between matching/oddity transfer tasks and same/different tasks may be procedural rather than conceptual.  相似文献   

Differential inhibition and stimulus generalization cannot account for value transfer in simultaneous discrimination learning by pigeons: Reply to Aitken     

Thomas R. Zentall  Brigette R. Dorrance  Tricia S. Clement 《Learning & behavior》1999,27(4):494-496

Aitken (1999) argues that, in a simultaneous discrimination, reports of the transfer of value from the positive to the negative stimulus can be more readily explained in terms of an artifact produced by the procedure in which differential inhibition accrues to the negative test stimuli during training, together with stimulus generalization (similarity between the positive and negative stimuli). We argue that (1) there is little evidence for differential inhibition, and it often occurs in the wrong direction; (2) value transfer can be demonstrated when differential value is established to the positive stimuli afterdiscrimination training, when differential inhibition is not likely to be a factor; and (3) on both logical and empirical grounds, stimulus similarity does not provide an adequate account of the transfer of value from the positive to the negative stimulus (i.e., the strongest evidence for value transfer occurs when there is least stimulus similarity). We propose that value transfer occurs whenever there is relatively little experience with the negative stimuli. However, when there is extended experience with the negative stimuli, contrast will be found.  相似文献   

Within-event learning contributes to value transfer in simultaneous instrumental discriminations by pigeons     

Brigette R. Dorrance  Thomas R. Zentall 《Learning & behavior》1999,27(2):206-210

Following simultaneous discrimination training with pigeons, in which responding to the S−was reinforced on half of the trials and responding to the S− was never reinforced, we examined the effect on the S− of presenting the S− by itself and the effect on the S+ of presenting the S− by itself (relative to an S− or an S− for which there had been no single-stimulus presentations). For Group A−, responding to the S− presented by itself was always reinforced, whereas for Group A−, such responding was extinguished. For Group B−, responding to the S− presented by itself was always reinforced, whereas for Group B+, responding was extinguished. Although both Group A+ and Group A−tended to avoid their associated S− (relative to a control S−), Group A+ avoided its associated S− less than did Group A−. In contrast, although for Group B−, presentation of the S− alone increased the pigeons’ preference for its associated S−(relative to a control S+), for Group B−, presentation of the S−alone had little effect on its preference for its associated S+. These results suggest that presentation of one stimulus from a simultaneous discrimination has two independent and sometimes opposite effects on the other discriminative stimulus. First, it reduces the strength of within-event conditioning between the S+ and the S−, and second, if the value of the singly presented stimulus has increased, some of its newly acquired value will transfer retroactively to the stimulus with which it was originally paired.  相似文献