Common control by compound samples in conditional discriminations

We tested whether teaching control by single stimulus samples in conditional discriminations would result in common control of two-stimuli compound samples, and vice versa. In Experiment 1, 5 participants were first taught four single-sample conditional discriminations. The first conditional discrimination was as follows: given sample stimulus P1, select comparison stimulus A1 and not A2; given sample P2 select comparison A2 and not A1. The second conditional discrimination was as follows: given sample P1 select comparison B1 and not B2; given sample P2 select B2 and not B1. Different sample stimuli (Q1 and Q2) were used in the third and fourth conditional discriminations. Moreover, A1 and B1 were presented together as comparisons, such that, if Q1 was presented as the sample, A1 was correct and B1 was incorrect; and if Q2 was presented as the sample, B1 was correct and A1 was incorrect. A2 and B2 were also presented as comparisons. When Q1 was presented, A2 was correct and when Q2 was presented B2 was correct. After training with these four single stimulus sample discriminations, participants were tested with compound PQ samples presented with A1, A2, B1, and B2 as comparisons. If common control were established by the PQ stimuli, a participant would select A1 when P1Q1 was presented, A2 when P2Q1 was presented, B1 when P1Q2 was presented, and B2 when P2Q2 was presented. Such common control by PQ samples occurred in 4 of 5 participants. In Experiment 2, 4 participants were given reverse training. They were first taught to select the A1, A2, B1, and B2 stimuli in response to the appropriate PQ combinations and then probed on the single stimulus sample discriminations. All 4 participants were successful on this probe. Experiments 3 and 4 investigated the effects of teaching additional conditional discriminations with novel stimuli on subsequent transfer from the single-sample discriminations to performance on the compound-sample conditional discrimination.     

ASSOCIATIVE SYMMETRY,ANTISYMMETRY, AND A THEORY OF PIGEONS' EQUIVALENCE‐CLASS FORMATION

Five experiments assessed associative symmetry in pigeons. In Experiments 1A, 1B and 2, pigeons learned two‐alternative symbolic matching with identical sample‐ and comparison‐response requirements and with matching stimuli appearing in all possible locations. Despite controlling for the nature of the functional stimuli and insuring all requisite discriminations, there was little or no evidence for symmetry. By contrast, Experiment 3 demonstrated symmetry in successive (go/no‐go) matching, replicating the findings of Frank and Wasserman (2005). In view of these results, I propose that in successive matching, (1) the functional stimuli are stimulus‐temporal location compounds, (2) continual nonreinforcement of some sample‐comparison combinations juxtaposed with reinforcement of other combinations throughout training facilitates stimulus class formation, (3) classes consist of the elements of the reinforced combinations, and (4) common elements produce class merger. The theory predicts that particular sets of training relations should yield “antisymmetry”: Pigeons should respond more to a reversal of the nonreinforced symbolic baseline relations than to a reversal of the reinforced relations. Experiment 4 confirmed this counterintuitive prediction. These results and other theoretical implications support the idea that equivalence relations are a natural consequence of reinforcement contingencies.     

Effects of within-class differences in sample responding on acquired sample equivalence

Two experiments examined whether acquired sample equivalence in many-toone matching was affected by variation in sample-response requirements. In each experiment, pigeons responded on either identical or different response schedules to the sample stimuli that occasioned the same reinforced comparison choice (i.e., to the within-class samples). Transfer-of-control tests were then conducted to determine acquired equivalence, or lack thereof, between these samples. In both experiments, there was minimal or no evidence of acquired sample equivalence when pigeons responded differently to the samples within each common-choice class. By contrast, transfer was observed if pigeons responded (a) identically to all sample stimuli, or (b) identically to samples within each common-choice class (viz., to samples that occasioned the same reinforced choice) and differently to samples from different classes (viz., to samples that occasioned different choices). These results may help to explain the recent lack of evidence for response membership in pigeons' acquired equivalence (Urcuioli, Lionello-DeNolf, Michalek, & Vasconcelos, 2006). They also raise questions about the functional sample stimuli and about possible interactions between acquired equivalence and acquired distinctiveness.     

Relational learning in children with deafness and cochlear implants

This four-experiment series sought to evaluate the potential of children with neurosensory deafness and cochlear implants to exhibit auditory-visual and visual-visual stimulus equivalence relations within a matching-to-sample format. Twelve children who became deaf prior to acquiring language (prelingual) and four who became deaf afterwards (postlingual) were studied. All children learned auditory-visual conditional discriminations and nearly all showed emergent equivalence relations. Naming tests, conducted with a subset of the children, showed no consistent relationship to the equivalence-test outcomes. This study makes several contributions to the literature on stimulus equivalence. First, it demonstrates that both pre- and postlingually deaf children can acquire auditory-visual equivalence relations after cochlear implantation, thus demonstrating symbolic functioning. Second, it directs attention to a population that may be especially interesting for researchers seeking to analyze the relationship between speaker and listener repertoires. Third, it demonstrates the feasibility of conducting experimental studies of stimulus control processes within the limitations of a hospital, which these children must visit routinely for the maintenance of their cochlear implants.     

“Plausible insofar as it is intelligible”: Quine on underdetermination

Quine’s thesis of underdetermination is significantly weaker than it has been taken to be in the recent literature, for the following reasons: (i) it does not hold for all theories, but only for some global theories, (ii) it does not require the existence of empirically equivalent yet logically incompatible theories, (iii) it does not rule out the possibility that all perceived rivalry between empirically equivalent theories might be merely apparent and eliminable through translation, (iv) it is not a fundamental thesis within Quine’s philosophy, and (v) it does not carry with it the anti-realistic consequences often associated with the thesis in recent debates. The paper analyzes Quine’s views on the matter and the changes they underwent over the years. A conjecture is put forth about why Quine’s thesis has been so widely misrepresented: Quine’s writings up to 1975 tackled primarily the formulation and justification of the thesis, but afterwards were concerned mostly with the question whether empirically equivalent rivals to the theory we hold are to be considered true also. When this latter discussion is read without bearing in mind Quine’s earlier formulation and justification of the thesis, his thesis seems to have stronger epistemic consequences than it actually does. A careful reading of his later writings shows, however, that the formulation of the thesis remained unchanged after 1975, and that his mature and considered views supported only a very mitigated version of the thesis.     

Six-member stimulus classes generated by conditional-discrimination procedures

In conditional-discrimination procedures with three sets of stimuli, A, B, and C, three stimuli per set (A1A2A3, B1B2B3, and C1C2C3), subjects (children and adults) learned to select Set-B and Set-C comparisons conditionally upon Set-A samples (A1B1, A1C1, A2B2, A2C2, A3B3, A3C3). If the conditional-discrimination procedures also generated equivalence relations, three 3-member stimulus classes would be demonstrable, A1B1C1, A2B2C2, and A3B3C3. In addition to these three sets, the present experiments used three other sets of stimuli--D, E, and F. The subjects learned to select Set-E and Set-F comparisons conditionally upon Set-D samples (D1E1, D1F1, D2E2, D2F2, D3E3, D3F3). This established a second group of three 3-member stimulus classes, D1E1F1, D2E2F2, and D3E3F3. In all, two groups of three 3-member classes were established by teaching subjects 12 conditional discriminations. The two groups of 3-member classes were then combined (successfully for 5 of 8 subjects) into a single group of three 6-member classes by teaching the subjects three more conditional relations (E1C1, E2C2, and E3C3). With three other children, enlarging the classes one member at a time also produced 6-member classes. As a consequence of class formation, 60 untrained conditional relations emerged from 15 that had been explicitly taught. Six of the subjects also proved capable of naming the stimuli consistently in accord with their class membership, but two subjects demonstrated class formation even in the absence of consistent naming.     

Differential vocalization in budgerigars: towards an experimental analysis of naming.

In Experiment 1, 3 budgerigars (Melopsittacus undulatus) were trained with food reinforcement to make low- or high-frequency calls in response to different color stimuli, C1 and C2 (a color-naming task), using a gradual response-differentiation procedure and an automatic call-recognition system. Thus, a call within a certain frequency band was reinforced in the presence of C1 ("C1 call"), and a call within a different band was reinforced in the presence of C2 ("C2 call"). In Experiment 2, all 3 budgerigars were trained in a form-to-color matching-to-sample task, alternating trial by trial with either the color-naming task (2 birds) or an identity color matching-to-sample task (1 bird). Sample stimuli for the new matching-to-sample task were forms (F1 or F2) and comparisons were the same two colors (C1 and C2). Given Sample F1 or F2, birds had to make a call to produce Comparison Pair C1 and C2. With F1 as the sample, a peck on C1 was reinforced; with F2 as the sample, a peck on C2 was reinforced. Although no particular call was specified in the presence of F1 and F2, 2 birds made the C1 call in the presence of F1 and the C2 call in the presence of F2. In Experiment 3, the bird that failed to match form and color calls in Experiment 2 and another bird were first trained in a color-to-form matching-to-sample task: C1 to F3 and C2 to F4. In this task, to produce the comparison pair of forms, a high call (or low for the other bird) was required in the presence of C1, and a low call (or high) was required in the presence of C2. Both birds were then trained with an identity matching-to-sample task in which sample and comparison stimuli were the same two forms, F3 and F4. Trials on the identity task alternated with the color-to-form trials. Although no particular call was required in the presence of Samples F3 and F4, both birds came to make the C1 call in the presence of F3 and the C2 call in the presence of F4. Our technique promises to be useful for the study of emergent vocal relations in budgerigars and other animals.     

Why behavior analysts should study emotion: the example of anxiety.

Historically, anxiety has been a dominant subject in mainstream psychology but an incidental or even insignificant one in behavior analysis. We discuss several reasons for this discrepancy. We follow with a behavior-analytic conceptualization of anxiety that could just as easily be applied to emotion in general. Its primary points are (a) that language-able humans have an extraordinary capacity to derive relations between events and that it is a simple matter to show that neutral stimuli can acquire discriminative functions indirectly with no direct training; (b) that private events can readily acquire discriminative functions; (c) that anxiety disorders seem to occur with little apparent direct learning or that the amount of direct learning is extraordinarily out of proportion with the amount of responding; and (d) that the primary function of anxious behavior is experiential avoidance. We conclude that the most interesting aspects of anxiety disorders may occur as a function of derived rather than direct relations between public events and overt and private responses with avoidance functions. Implicit in this conclusion and explicit in the paper is the assertion that anxiety is a suitable subject for behavior-analytic study.