Retardation and facilitation of matching acquisition by differential outcomes

Pigeons were trained on many-to-one matching-to-sample with food and no-food outcomes that were either differential or nondifferential with respect to the sample stimuli. In the differential condition, outcomes were correlated with the correct comparison-alternatives-for half of the subjects, and were uncorrelated with those alternatives for the remaining subjects. Relative to non-differential training, matching acquisition was facilitated in the correlated condition but retarded in the uncorrelated condition. These results clearly demonstrate that differential outcomes do not affect conditional discrimination learning merely by enhancing the discriminability or distinctiveness of the samples with which they are associated. Rather, they apparently give rise to another discriminative cue (viz., an outcome expectancy), which can either enhance or interfere with performance, depending on its predictive validity.     

Some tests of the anticipatory mediated generalization model of acquired sample equivalence in pigeons’ many-to-one matching

Transfer-of-control tests typically show the development of acquired equivalence between samples occasioning the same comparison choice in pigeons’ many-to-one matching-to-sample. Specifically, when some of those samples are later explicitly trained to occasion new comparison choices, the remaining samples immediately exert control over the new choices as well. In the present experiments, we examined whether or not this transfer effect depends on the order in which the various sample-comparison relations in training are learned. One group of pigeons initially acquired 0-delay many-to-one matching with four samples and two comparisons, followed by 0-delay matching with two of those samples and two new comparisons. Another group of pigeons learned the two-sample matching task first, followed by many-to-one matching. When subsequently tested for their ability to match the remaining samples from many-to-one matching to the comparisons used in the two-sample task, both groups showed comparable levels of transfer. These findings challenge the view that common anticipatory processes ostensibly arising from the samples in many-to-one matching are necessary mediators for the subsequent transfer effects indicative of acquired sample equivalence.     

Effects of signaled retention intervals on pigeon short-term memory

In three delayed matching-to-sample experiments, pigeons were given distinctive stimuli that were either correlated or uncorrelated with the scheduled retention intervals. Experiment 1 employed a single-key, go/no-go matching procedure with colors as the sample and test stimuli; lines of differing orientations signaled short or long delays for one group, whereas the lines and the delays were uncorrelated for the other group. The function relating discriminative test performance to delay length was steeper in the correlated group than in the uncorrelated group. In addition, the line orientation stimuli controlled differential rates of sample responding in the correlated group, but not in the uncorrelated group. In Experiment 2, subjects extensively trained with correlated line orientations were exposed to reversed cues on probe trials. Miscuing decreased discriminative test responding at the short delay, but enhanced it at the long delay. As in the correlated group of the first experiment, rates of sample keypecking were higher in the presence of the “short” time tag than in the presence of the ”long” time tag. Experiment 3 used a three-key choice-matching procedure and a within-subjects design, and equated reinforcement rate at the short and long delays. When auditory stimuli were correlated with delay length, the function relating choice accuracy to delay was steeper than when the stimuli and the delays were uncorrelated. The consistent effects of signaled retention intervals on memory performance may be understood in terms of differential attention to the sample stimuli.     

Expectancies as mediators in the differential-reward conditional discrimination performance of pigeons

In a series of within-subject experiments employing a two-choice delayed conditional discrimination task, pigeons chose correctly more often when kind of correct choice and kind of reinforcer were perfectly correlated than when uncorrelated. Correct choice behavior fell to chance levels when the correlation was reversed or when it was removed by using only one kind of reinforcer. Implications for mediation theories are discussed, with the conclusion being that, although the possibility that instrumental mediators are present in this situation cannot be dismissed, the overall pattern of results indicates that classical mediators are of principal importance in this type of task.     

Common coding by pigeons in a many-to-one delayed matching task as evidenced by facilitation and interference effects

Pigeons were first trained on many-to-one delayed matching in which pairs of hue and line-orientation samples were associated with individual comparison stimuli. They were then trained to match two of the original samples (either hues or line orientations) to new comparisons, after which 2-sec delays were inserted between the samples and comparisons. In testing, the remaining samples were presented as interpolated stimuli during the delays. When the interpolated stimulus had been associated with the same comparison as the sample in many-to-one matehing, performance was significantly more accurate than when it had been associated with a different comparison. This finding adds to the evidence that samples sharing common comparison associations are commonly coded.     

Differential-outcomes effect using hedonically nondifferential outcomes with delayed matching to sample by pigeons

When differential outcomes follow correct responses to each of two comparison stimuli in matching to sample, relative to the appropriate control condition, higher matching accuracy is typically found, especially when there is a delay between the sample and the comparison stimuli. In two experiments, we examined whether this differential-outcomes effect depends on using outcomes that differ in hedonic value (e.g., food vs. water). In Experiment 1, we found facilitated retention when a blue houselight followed correct responses to one comparison stimulus and a white houselight followed correct responses to the other, prior to nondifferential presentations of food. In Experiment 2, we found facilitated retention again when a blue houselight followed correct responses to one comparison stimulus and a tone followed correct responses to the other, prior to nondifferential presentations of food. The results of both experiments indicate that the differential-outcomes effect does not depend on a difference in hedonic value of the differential outcomes, and they suggest that outcome anticipations consisting of relatively arbitrary but differential stimulus representations can serve as cues for comparison choice.     

A differential-outcome effect in pigeons using spatial hedonically nondifferential outcomes

We examined the extent to which nonhedonically different differential outcomes involving feeder location control pigeons’ comparison choices in matching to sample. In Experiment 1, we showed that differential feeder location outcomes associated with each of two samples can facilitate delayed-matching accuracy. In Experiment 2, we found positive transfer following training on two matching tasks with differential feeder location outcomes when samples from one task were replaced by samples from the other task. In Experiment 3, we found that when differential-outcome expectations could no longer serve as the cues for comparison choice, sample stimuli continued to exert some control over choice of comparisons. The results indicate that differential outcomes (involving feeder location) that presumably do not differ in hedonic value are sufficient to control comparison choice. Thus, the differential hedonic value of the outcome elicited by the sample does not appear to be a requirement of the differential-outcome effect. Furthermore, these differential outcomes appear to augment matching accuracy, but they do not eliminate control by the samples.     

Transfer of performance to new comparison choices following differential outcome matching-to-sample

Four experiments examined transfer of differential outcome performances to new choice responses in pigeons. Experiments 1A and 1B showed that new responses trained off a matching-to-sample baseline readily substituted for the choice alternatives in differential outcome matching, provided that they shared the same outcome associations as the alternatives they replaced. Experiment 2 showed that comparison responses trained on baseline, but in a task in which their different outcomes occurred equally often following each sample (viz., one-to-many matching), substituted for the choices in a standard, differential outcome task. Experiment 3 showed, somewhat surprisingly, that the choices in the latter task were likewise effective substitutes in one-to-many matching. These results pose separate challenges for standard two-process theory and for the bidirectional account of differential outcome performance, and they suggest other cues that pigeons may use to predict outcomes.     

Some relationships between outcome expectancies and sample stimuli in pigeons’ delayed matching

Two sets of experiments examined how differential outcomes affect conditional stimulus control by the samples in delayed matching-to-sample. Pigeons were initially trained on symbolic delayed matching with reinforcing outcomes that were either differential or nondiffereatial with respect to the samples. In one set of experiments, the outcome manipulation involved different (p = 1.0 vs. 0.2) versus the same (p = 0.6) probabilities of food; in the other, food and no-food outcomes were used. Following initial acquisition and mixed-delay tests, the matching procedure in each study was discontinued while the samples were nondifferentially reinforced with the same probability of food, or with food and no food, respectively. When later retested on delayed matching with those nondifferential outcomes, birds initially trained with different reinforcement probabilities matched at the same levels of accuracy as those trained with the same probability. By contrast, birds initially trained with food versus no-food outcomes showed lower levels of matching accuracy than their nondifferential controls. Subsequent transfer tests showed that matching performances by the differential birds in both studies had been originally cued in part by differential outcome expectancies. Apparently, the expectancies based upon different probabilities of food provided a source of conditional stimulus control that did not compete with the samples. By contrast, the expectation of food versus no food reduced (overshadowed) sample-stimulus control.     

Prospective representation: The effects of varied mapping of sample stimuli to comparison stimuli and differential trial outcomes on pigeons’ working memory

The mapping of sample stimuli onto comparison stimuli and the nature of trial outcomes were factorially manipulated in a delayed matching-to-sample procedure. In the many-to-one condition (MTO), responding to a particular comparison was correct following several sample stimuli, whereas in the one-to-many condition (OTM), responding to several comparison stimuli was correct following a particular sample. Probabilities of reinforcement for correct responding to comparison stimuli were either differential (DO) or nondifferential (NDO). Four groups of pigeons were trained under four combinations of mapping and outcome conditions, MTO-DO, MTO-NDO, OTM-DO, and OTM-NDO. Testing at delay intervals of 1, 2, 4, and 8 sec revealed significant effects due to both the mapping variable and the differential outcomes variable. It was argued that the poorer performance obtained in the OTM condition was due to the differential prospective coding requirements placed on reference and working memory by this mapping. In the OTM conditions, a greater number of response codes had to be retrieved from reference memory and multiple response codes may have overburdened working memory, which has a limited capacity.     

The instinct fallacy: the metacognition of answering and revising during college exams

Students often gauge their performance before and after an exam, usually in the form of rough grade estimates or general feelings. Are these estimates accurate? Should they form the basis for decisions about study time, test-taking strategies, revisions, subject mastery, or even general competence? In two studies, undergraduates took a real multiple-choice exam, described their general beliefs and feelings, tracked their performance for each question, and noted any revisions or possible revisions. Beliefs formed after the exams were poor predictors of performance. In contrast, real-time metacognitive monitoring – measured by confidence ratings for each individual question – accurately predicted performance and were a much better decisional guide. Measuring metacognitive monitoring also allowed us to examine the process of revising an answer. Should a test-taker rely on their first choice or revise in the face of uncertainty? Experience seems to show that first instincts are correct. The decision-making literature calls this the first-instinct fallacy, based on extensive analysis of revisions, and recommends revising more. However, whereas revisions have been analyzed in great detail, previous studies did not analyze the efficacy of sticking with an original choice. We found that both revising and sticking resulted in significantly more correct than incorrect outcomes, with real-time metacognition predicting when each was most appropriate.     

Young children's reasoning about many-to-one correspondences

Young children's understanding of many-to-one correspondence problems was studied to illuminate the developmental transition from additive to multiplicative numerical knowledge. A many-to-one correspondence exists when a fixed number of target objects (greater than 1) is associated with each of a set of referents, as in putting 3 flowers in each of several vases. Two experiments examined effects of a brief training procedure that highlighted the iterative nature of many-to-one mappings. In Experiment 1, 5- and 6-year-old children did not benefit from the training, but a subset of 7-year-olds did. In Experiment 2, 7-year-olds showed training effects that extended to generalization problems. Patterns of performance across experimental and generalization problems suggested that some children had difficulty applying what they learned from training to the experimental problems.     

“Same/different” symbol use by pigeons

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.     

Enhancement of pigeons’ conditional discrimination performance by expectancies of reinforcement and nonreinforcement

Prior work has shown that when the separate correct responses of a conditional discrimination are followed by different reinforcing outcomes, performance is enhanced relative to that obtained under the conventional, single-reinforcer procedure. Four experiments with pigeons yielded the analogous finding when the different outcomes were reinforcement and explicit nonreinforcement. Controls indicated that the results could not be attributed to the effects of intermittent reinforcement, to possible differences in cue duration, or to a variety of potential sources of conditioned reinforcement. An interpretation in terms of expectancy learning is proposed.     

Polymorphic response patterns under frequency-dependent selection

In a discrete-trials procedure, a frequency-dependent schedule shaped left-right choice proportion toward various equilibrium values between 0 and 1. At issue was (1) whether pigeons match when the overall reinforcement probabilities for two responses depend inversely on their recent frequency, and (2) how pigeons meet the schedule constraint in terms of local responding. That is, do they respond quasi-randomly (Bernoulli mode), or do they learn the stable pattern of the schedule (stable-pattern mode)? Molar choice behavior always tracked the equilibrium solution of the schedule, but the molecular response patterns varied substantially. Markov chains applied to the data revealed that responding was generally intermediate between the memoryless Bernoulli mode, and the perfect memory stable-pattern mode. The polymorphism of molecular patterns, despite molar regularities in behavior, suggests that (1) in order to engender the Bernoulli or stable-pattern modes, the reinforcement rule must strongly discourage competing response patterns (e.g., perseveration), and (2) under frequency-dependent schedules, molar matching is apparently not the outcome of momentary maximizing.     

Development of excitatory backward associations during the establishment of forward associations in a delayed conditional discrimination by pigeons

The development of excitatory backward associations in pigeons was demonstrated in three experiments involving conditional discriminations with differential outcomes. In Phase 1 of all three experiments, correct comparison choices following one sample were followed by food, whereas correct comparison choices following the other sample were followed by presentation of an empty feeder. In Phase 2, the food and no-food events that served as outcomes in Phase 1 replaced the samples. When the associations tested in Phase 2 were consistent with the comparison-outcome associations developed in Phase 1, transfer performance was significantly better than when the Phase 2 associations were inconsistent with the Phase 1 associations. In Experiment 1, an identity matching-to-sample task was used with red and green samples and red and green comparisons. In Experiment 2, a symbolic matching task was used with shape samples and hue comparisons, and it was shown that the backward associations formed were between the trial outcome (food or no food) and the correct comparison. In Experiment 3, it was determined that the transfer effects observed in these experiments did not depend on either the similarity of behavior directed toward the samples in the training and test phases, or the similarity of food and no-foodexpectancies generated by the samples in Phase 1 to food and no-foodevents presented as samples in Phase 2.     

Matching/mismatching revisited: an empirical study of learning and teaching styles

This paper presents results of a research project that explored the relationship between matching and mismatching instructional presentation style (breadth-first and depth-first) with students' cognitive style (field-dependence/-independence) in a computer-based learning environment. 73 postgraduate students were asked to create Web pages using HTML, using instructional materials that were either matched or mismatched with their cognitive styles. Significant differences in performance on a multiple choice test of conceptual knowledge were found for students learning in matched and mismatched conditions. Performance in matched conditions was significantly superior to that in mismatched conditions. However, significant effects were found for gender, matching mainly affecting male students. Performance on a practical test of Web page creation was not linked to matching or mismatching, but was linked to an interaction between gender and instructional presentation style. The findings provide support for the notion that matching and mismatching can have significant effects on learning outcomes. The paper concludes with suggestions for further research.     

Coding of hedonic and nonhedonic samples by pigeons in many-to-one delayed matching

In two experiments, pigeons were trained on many-to-one delayed matching in which samples of food and one hue were each associated with one shape comparison, and samples of no food and a different hue were each associated with a second shape comparison. When later tested with delays between sample and comparison stimuli, pigeons showed nonparallel delay functions, typically found with food and no-food samples (i.e., steeply declining food-sample delay functions, and relatively flat no-food-sample delay functions). Furthermore, the slopes of the hue-sample delay functions were similar to those on the food/no-food-sample trials. In Experiment 2, following many-toone delayed matching, when the hue samples were associated with new comparisons and then food and no-food samples replaced the hues, evidence was found for transfer of training indicative of the common coding of samples associated with the same comparison in original training. The transfer results suggest that the asymmetrical hue-sample functions resulted from the common coding of samples associated with the same comparison.     

Object recognition through eavesdropping: Passive echolocation in bottlenose dolphins

A bottlenose dolphin (Tursiops truncatus) demonstrated the ability to select the matching object in a matching-to-sample task after listening to another dolphin inspect the sample object via echolocation. The listener was prevented from inspecting the sample himself. In Experiment 1, with objects familiar to both dolphins, the listener’s performance was significantly better than chance. In Experiment 2, objects familiar to only one of the dolphins were used. On these trials, the listener’s performance was significantly better than chance only when the inspecting dolphin made a correct choice. Analysis of the listener’s responses when the inspector made an error demonstrated that this contingency was not due to the listener’s matching the inspector’s response, but was apparently due instead to inadequate information in the echo. The results suggest that the listener was able to “eavesdrop” on echoes produced by the inspector’s clicks and derive characteristics of the sample object.