Sequential effects on discrimination reversal

In Experiment 1 the sequence of trials to the positive (S+) and negative (S?) discriminanda was varied between groups during acquisition and reversal of a successive brightness discrimination. In Experiments 2 and 3, groups received different reward sequences in Phase 1 within S+. In general, groups given transitions from nonrewarded trials to rewarded trials (N-R transitions) in Phase 1 learned both the original discrimination and its reversal more slowly than groups given schedules devoid of N-R transitions. The results were discussed in relation to previously reported effects of partial reinforcement on acquisition and reversal of a discrimination and the role of sequential variables and internal, reward-produced cues in discrimination learning, reversal learning, and nonreversal shifts.     

Contextual control in discrimination reversal learning

In 3 human predictive learning experiments, the authors examined contextual control of responding in discrimination reversal learning. In Phase 1, a discrimination between 2 stimuli (A+, B-) was trained in Context 1. During Phase 2, participants received discrimination reversal training (A-, B+) in Context 2. Testing occurred in Context 1 and Context 2 (Experiments 1A and 1B) or in Context 1 and Context 3 (Experiment 2). During the test phase, performance in Context 1 and Context 2 reflected the contingencies trained during Phase 1 and Phase 2, respectively. When testing occurred in Context 3, there was no discriminative responding between A and B. In addition, the experiments demonstrated that discriminating stimuli with a consistent reinforcement history were also affected by contextual manipulations. Results indicate that each training context acquires the ability to control performance. Unique-cue and configural approaches account for a major part of the results.     

Effects of error and errorless discrimination acquisition on reversal learning

The effectiveness of trial-and-error, graded-choice, and verbal-instruction procedures on the acquisition and maintenance of a two-choice simultaneous color discrimination in an intradimensional double-reversal learning situation was studied using 18 first-grade children. After acquiring a red-green discrimination during one 70-trial session, the discriminative roles of the stimuli were reversed for 30 trials, followed by a second reversal for 30 trials. Children in the graded-choice and verbal-instruction groups acquired and maintained the discriminations with fewer errors than children who learned by trial and error. The importance of the results in terms of two-stage discrimination learning theories is pointed out and similarities between errorless learning and overtraining are discussed.     

Form preferences in successive discrimination learning of young chicks.

In four experiments the effects of form and orientation pecking preferences of 1- and 3-day old Vantress X Arbor Acre chicks on successive discrimination learning were determined, using heat reinforcement. Major findings were as follows: (a) The young chick has both circle and verticle orientation pecking preferences that are present during at least the first 3 days after hatching; (b) when either of these preferred cues is the nonreinforced cue, the young chick has difficulty in learning not to respond to it but learns quickly not to respond to an unpreferred cue (e.g., triangle and horizontal oriented dots or bar); and (c) these pecking preferences can be modified by heat reinforcement, and the effects of this conditioning is evidenct in subsequent extinction and retention tests. The main conclusion from these experiments is that form and orientation preferences, like brightness and color preferences, are important developmental constraints on conditioning of the young chick.     

Sex differences in discrimination reversal learning in the guppy

In several mammalian and avian species, females show a higher performance than males in tasks requiring cognitive flexibility such as the discrimination reversal learning. A recent study showed that female guppies are twice as efficient as males in a reversal learning task involving yellow–red discrimination, suggesting a higher cognitive flexibility in female guppies. However, the possibility exists that the superior performance exhibited by females does not reflect a general sex difference in cognitive abilities, but instead, is confined to colour discrimination tasks. To address this issue, we compared male and female guppies in two different discrimination reversal learning tasks and we performed a meta-analysis of these experiments and the previous one involving colour discrimination. In the first experiment of this study, guppies were tested in a task requiring them to learn to select the correct arm of a T-maze in order to rejoin a group of conspecifics. In experiment 2, guppies were observed in a numerical task requiring them to discriminate between 5 and 10 dots in order to obtain a food reward. Although females outperformed males in one condition of the T-maze, we did not find any clear evidence of females’ greater reversal learning performance in either experiment. However, the meta-analysis of the three experiments supported the hypothesis of females’ greater reversal learning ability. Our data do not completely exclude the idea that female guppies have a generally higher cognitive flexibility than males; however, they suggest that the size of this sex difference might depend on the task.     

Infantile handling and the facilitation of discrimination and reversal learning

One group of rats was removed from their home cage and received daily handling from Days 3-21, while the control group of litter mates remained in the cage and did not receive any treatment. On Day 22 all rats were weaned and they were housed in individual cages until they were 60 days old. After two pretraining days, subjects were given daily blocks of one free and three forced trials in the T-maze and were rewarded with food after making the correct response. Following 20 days of training and testing on black-white discrimination, subjects were given 10 days of reversal training with four daily trials. Results indicate that the handled animals showed faster running and a greater number of correct choices than the control rats during both the acquisition and reversal learning phases of the experiment.     

Effects of monochromatic rearing on spectral discrimination learning and the peak shift in chicks

Chicks were hatched and raised in white or monochromatic sodium (589 nm) light. They were trained on a 590 (+) vs. 580 (-) nm successive discrimination. The combined results of two experiments indicated that rearing illumination did not affect discrimination acquisition. All subjects given generalization tests after discrimination training exhibited peak shifts that were equivalent for the two rearing conditions. The peak shifts exhibited by the monochromatically reared subjects represent maximum responding to stimuli they had not previously seen. This result further confirms the notion that behavioral control by the spectral dimension in birds is organized independently of differential early experience on that dimension.     

The role of R-S1 expectancy in discrimination and discrimination reversal learning

Four experiments assessed the role of response-reinforcement (R-S¹) expectancy as rats either learned a discrimination or a discrimination reversal. Experiment 1 showed that the higher the percentage of reinforcement during nondiscriminative pretraining the more quickly a subsequent discrimination is learned. Experiment 2 demonstrated that the overlearning reversal effect (ORE) can be obtained even though the overtraining phase consists of responses to a single neutral card. In Experiment 3 subjects were again overtrained on a single neutral stimulus under conditions of varying reinforcement. ORE was apparent under reinforcement of a high percentage of responses but was not apparent under reinforcement of a low percentage. Experiment 4 revealed that the fewer errors a subject makes prior to reversal the better its reversal performance is. Results of these studies were discussed in terms of generalized attention theories and the expectancy notions of Bolles (Psychological Review, 1972, 79(5), 394–409.     

Variation in reversal learning by three generalist mesocarnivores

Animal Cognition - Urbanization imposes novel challenges for wildlife, but also provides new opportunities for exploitation. Generalist species are commonly found in urban habitats, but the...