David E. Hogan

Backward associations in the pigeon

The learning of backward associations by pigeons during training of forward associations was studied in three experiments using a symbolic matching task. When the sample stimulus remained present with the comparison stimuli, no evidence of learning of backward associations was found with colors as comparison stimuli and either colors (Experiment I) or shapes (Experiment II) as sample stimuli. When the sample stimulus was removed on presentation of the comparison stimuli (Experiment III), evidence of backward associations was found, but only over the first few transfer trials. The data are contrasted with the strong evidence of learning of backward associations by humans. An association between two events may consist of two components, a forward association and a backward association. After training, evidence of the establishment of a forward association comes from an organisms ability to anticipate a second event, or its consequence, given a first event. Evidence of the establishment of a backward association comes from an

Delayed matching in the pigeon: Effect on performance of sample-specific observing responses and differential delay behavior

Abstract Pigeons were trained on a delayed matching-to-sample task with a 0-sec delay and then transferred to a 1-sec delay (Experiment 1) or were trained with mixed 0-sec/1-sec delays and then transferred to longer mixed delays up to 28 sec (Experiment 2). Four groups were distinguished by the nature of the observing response required to each sample color (red and blue). For Group NN pecks were allowed to neither color. For Group PcPc pecks were required to both colors. For Group PcN pecks were required to red but were not allowed to blue. For Group PcPt pecks were required at the center key in the presence of red, but at a key located directly above the center key in the presence of blue. The results of both experiments indicated significant effects of both Pecking vs Not Pecking, and Sample-Specific vs Sample-Independent Responding. At the longer delays individual differences in sample-specific delay behavior were a better predictor of performance than the behavior required in the presence of the sample.

Memory in the pigeon: Proactive inhibition in a delayed matching task*

Six pigeons were trained on a wavelength matching-to-sample task with a 5-sec delay between the offset of the sample and onset of the comparison stimuli. When a novel wavelength or novel shape was interpolated between the sample and comparison stimuli, both disrupted matching performance, and the novel wavelength was more disruptive than the novel shape. The results suggest that interpolated stimulus presentation disrupts the memory trace for the sample stimulus.

Imitation and social facilitation in the pigeon

The sight of another pigeon pecking a response key for grain resulted in similar pecking by more pigeons than did the sight of another pigeon eating or the sight of another pigeon (neither pecking nor eating). But more pigeons pecked the response key when they could see another pigeon that was neither pecking nor eating than when no other pigeon was there (whether or not key-light/grain pairings were observable in the adjacent compartment). Finally, observation of another pigeon pecking but not eating produced pecking comparable to observation of both pecking and eating. The presence of both imitation and social facilitation of keypecking were demonstrated. Observation of the consummatory response contributed little to keypecking.

Delayed matching in the pigeon: Interference produced by the prior delayed matching trial

Pigeons’ delayed matching performance on Trial n was examined as a function of whether the correct and incorrect comparison stimuli from Trial n−1 were maintained in the same role on Trial n (positive transitions), were reversed in role on Trial n (negative transitions), or were absent on Trial n (neutral transitions). Relative to neutral transitions, positive transitions did not significantly facilitate performance. Negative transitions, however, produced significant proactive interference on Trial n, and the magnitude of proactive interference was greater when the Trial n retention interval was 1 sec than when it was 0 sec. As the intertriai interval increased from 2 to 10 sec, the amount of interference dissipated. The results suggest that a prior delayed matching trial can serve as a significant source of forgetting but not a significant source of facilitation on an immediately following delayed matching trial.

Short-term proactive inhibition in the pigeon

Abstract Proactive inhibition in the pigeon was studied using a delayed-color-matching-to-sample task, with and without presentation of stimuli prior to the sample. Interference theory predicts that, relative to control performance, the disruptive effects of a prior stimulus should increase over a retention interval, while decay theory predicts that such disruptive effects should decrease over time. Results supported decay theory when performance was at a low level and interference theory when performance was at a high level. With performance at an intermediate level, parallel functions were obtained, an outcome supporting neither theory. It was concluded that the results supporting interference and decay theories were artifactually produced by floor and ceilling effects, respectively, and it was suggested that the results of earlier experiments using the present paradigm may well have been influenced by similar artifacts. Inserting a nondisruptive stimulus between a prior disruptive stimulus and the sample virtually eliminated the disruptive effects of the prior stimulus when tested immediately, but not when tested after 1 sec. The results of the present experiments and related findings can best be explained by either a modified decay theory (Grant, D. S. Proactive interference in pigeon short-term memory. Journal of Experimental Psychology: Animal Behavior Processes 1975, 104, 207–220) or a modified temporal discrimination theory.

Comparison of two oddity tasks with pigeons

Abstract Two oddity tasks were compared: one in which the odd stimulus could appear on any of the three stimulus positions (true oddity); the other in which the odd stimulus could only appear on the left or right but not the center (oddity-from-sample). A stimulus-configuration theory predicts faster oddity-from-sample learning, whereas a theory, based on shifts in observing over trials, predicts faster learning of true oddity. Pigeons learned the oddity-from-sample task faster, thus supporting configuration theory. Performance on the oddity-from-sample task but not the true oddity task was facilitated by increasing the number of responses required to terminate a trial. When the oddity-from-sample pigeons were shifted to the true oddity task, no evidence of positive transfer was found, suggesting that a configuration theory alone is insufficient to explain differences in acquisition. Only when a correction procedure was introduced did the true oddity pigeons perform above 50%.

Oddity learning in the pigeon: Effect of negative instances, correction, and number of incorrect alternatives

Pigeons have difficulty learning a standard oddity task involving two colors and three stimulus positions. In Experiment 1, performance on standard noncorrection trials was compared with performance on (1) rerun correction trials in which errors resulted in trial repetition, (2) noncorrection trials with added “negative instance” trials involving presentation of three stimuli, all of which matched, and (3) a combination of correction and added negative instance trials. Results indicated that negative instances, but not correction trials, significantly facilitated oddity performance. In Experiment 2, Phase 1, number of stimulus positions lit (three or five) was factorially manipulated with number of positions on which the odd stimulus could appear (three or five). An increase in number of positions lit, but not number of positions that could be odd, facilitated performance. In Phase 2, birds transferred from trials with five positions lit to four positions lit performed significantly better than controls; but in Phase 3, the same birds did not perform significantly better than controls when transferred to trials with three positions lit. In both experiments, analysis of performance as a function of response position indicated better performance at the end of each display than in the middle. These results, together with the group performance differences in Experiment 2, suggest that oddity learning in pigeons involves a size, or number, discrimination.

Music Training and Semantic Clustering in College Students

College students with 5 or more years of music training recalled significantly more words from a 16-item word list than did students with 0-4 years of training. The superior recall of the extensively trained students linked to better application of a semantic-clustering strategy across a series of 3 test trials. Music education and language experience may have similar influences on the development of verbal memory.

Observational learning of a conditional hue discrimination in pigeons

Abstract Three experiments examined a relationship between cooperation and observational learning in pigeons using procedures similar to Skinner (1962) . In Experiment 1, dyads cooperated by searching and pecking nearly simultaneously on the correct pair of adjacent keys of a 2 × 2 matrix. The dyads learned to search for the correct keys in a coordinated fashion, but only if they were permitted to watch one anothers performance. Experiment 2 disconfirmed the hypothesis that the coordinated performance of cooperating pigeons reflects an unlearned response tendency to peck at locations close to where the other bird is pecking. Experiment 3 demonstrated that prior cooperation training involving an observer and demonstrator pigeon facilitated subsequent observational learning of a conditional hue discrimination. Cooperation training appeared to facilitate observational learning by establishing the demonstrators peck response as an instructional stimulus which indicated the reward significance of the discriminative stimuli.