Conceptual Differences in the Analysis of Stimulus Equivalence (original) (raw)
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The relation between stimulus function and equivalence class formation
Journal of the Experimental Analysis of Behavior, 2004
Fifty participants were exposed to a simple discrimination-training procedure during which six Sϩ functions were established for six arbitrary stimuli, and SϪ functions were established for a further six stimuli. Following this training, each participant was exposed to one of five conditions. In the Sϩ condition, participants were exposed to a stimulus equivalence training and testing procedure using only the six Sϩ stimuli as samples and comparisons. In the Sϩ/SϪ condition, participants were exposed to the same training and testing sequence as in the Sϩ condition, the difference being that three Sϩ and three SϪ stimuli were used as sample and comparison stimuli, with each set of three corresponding to the trained equivalence relations. In the Sϩ/SϪ mixed condition, the Sϩ and SϪ stimuli were assigned to their roles as samples and comparisons in a quasi-random order. In the SϪ condition, all six SϪ stimuli were used. The no-function condition served as a control condition and employed stimuli for which no stimulus-control functions had been established. The results showed that, on average, participants required more testing trials to form equivalence relations when the stimuli involved were functionally similar rather than functionally different. Moreover, participants required more test trials to form equivalence relations when novel arbitrary stimuli, rather than functionally distinct stimuli, were used as samples and comparisons. The speed of acquisition of stimulus equivalence was also related to the number of functionally similar stimuli established before training. These findings indicate a variety of ways in which the emergence of equivalence relations is affected by the functional classes in which the relevant stimuli participate.
Training and Testing Parameters In Formation of Stimulus Equivalence: Methodological Issues
Research on stimulus equivalence has been prominent for more than 40 years in behavior analysis. The present article will focus on issues related to methodological considerations in stimulus equivalence research. An introduction to stimulus equivalence is provided, followed by a discussion of parameters in training conditional discriminations and testing for the emergence of equivalence classes. Some issues related to different training structures, the use of instructions, simultaneous versus delayed matching to sample, the role of familiar stimuli, response requirements for the sample stimulus, and criteria for (a) defining responding in accordance with equivalence and (b) establishing conditional discrimination are discussed in more detail.
An "Orwellian" account of stimulus equivalence. Are some stimuli "more equivalent" than others?
Stimulus equivalence is widely accepted as a model of semantic relations. However, few studies have used methods other than matching-to-sample to assess whether equivalent stimuli are semantically related. This article describes that formed equivalence classes with arbitrary stimuli and faces expressing emotions. A semantic differential showed that the arbitrary stimuli were then evaluated similarly to the faces, indicating that they had acquired similar meanings. The semantic differential permitted a quantitative assessment of the degree of relatedness between equivalent stimuli, and showed that relatedness varied as a function of nodal distance and simultaneous or delayed matching in training. Another study confirmed the semanticity of relations between faces expressing emotions and their equivalent stimuli through the IRAP. This study also confirmed that stimuli in classes formed with delayed matching-to-sample are more strongly related than those in classes formed with simultaneous matching.
Stimulus familiarity and the delayed emergence of stimulus equivalence or consistent nonequivalence
Psychological Record, 1998
Stimulus equivalence, defined as C-A matching, was tested in 80 adults following training in a matching-to-sample task involving arbitrary A-B and B-C matching. In Experiment 1, 50 subjects, successively assigned to one of five groups, were exposed to specific stimulus material. The stimuli for subjects in the first group were Greek letters only. In the remaining groups, pictures were incorporated as A-, B-, and/or C-stimuli. The probability of equivalence was low when the stimulus material consisted only of Greek letters. For the remaining groups, the probability of equivalence varied considerably depending upon whether the A-, B-, and/or C-stimuli were pictures. The results indicate that seemingly minimal procedural variations can yield markedly differential outcomes not predicted by any existing model. The results also showed that responding gradually may become consistent with a pattern other than the predicted equivalence pattern. Experiment 2 replicated the results of Experiment 1 showing (a) differential probabilities of equivalence in individual subjects, depending upon the configuration of Greek letters and pictures during training/testing, (b) consistent patterns of responding even when the responding was not in accord with equivalence, and (c) higher reaction times to comparison stimuli initially during testing. Probabilities of equivalence increased in a second exposure to the tasks involving only Greek letters, whether or not the subjects were exposed to a task with pictures prior to the second Greek-letter task. Higher reaction times initially during testing may indicate precurrent problem solving behavior prior to the selection of a comparison stimulus. The finding of delayed emergence of consistent responding suggests that even the slightest tendency toward responding that partitions the stimuli into the experimenter-planned equivalence classes may evolve into consistent responding in accord with those classes. The authors gratefully acknowledge Charles Catania for his comments on an earlier version of this manuscript.
Variation in baseline controlling relations is suggested as one of the factors determining variability in stimulus equivalence outcomes. This study used single-comparison trials attempting to control such controlling relations. Four children learned AB, BC, and CD conditional discriminations, with 2 samples and 2 comparison stimuli. In Condition A, a mask always covered the S+ or the S−, each in 50% of the training trials, ensuring both sample-S+ and sample-S− controlling relations. In subsequent tests, children showed immediate equivalence formation. Condition B trained the same sequence of conditional discriminations with different stimuli, attempting to prevent sample-S+ control in the BC conditional discrimination. Two children did not show equivalence, whereas the other 2 did. Probes suggested that children who formed equivalence in Condition B acquired sample-S+ relations, even with training designed to prevent them. Results indicate that acquisition of both sample-S+ and sample-S− relations increases the probability of immediate equivalence formation.
Stimulus Equivalence: A Laboratory Artefact or the Heart of Language?
2015
This thesis surveys some of the implications of the presented collection of publications, all of which address the phenomenon of stimulus equivalence. Stimulus equivalence (SE) is first operationally defined in terms of Sidman’s trio of criteria: symmetry, transitivity, and reflexivity (Sidman & Tailby, 1982). Then some of its main features – the phenomenon of delayed emergence, the effects of nodes, and the influence of properties of the stimuli used, including nameability and meaningfulness - as exemplified in the empirical studies presented, are evaluated in the light of recent literature. The variety of ways in which SE classes may be formed are described, and the question of when SE relations take effect – during the training of the base relations, or subsequently, or only in the course of unreinforced testing for derived relations – is discussed. The effects of nodal number in multi-nodal linear classes are examined and contrasted with those in serial learning. Some methods of...
Stimulus generalization and equivalence classes: a model for natural categories
Journal of the Experimental Analysis of Behavior, 1991
Two three-member classes were formed by training AB and BC using a conditional discrimination procedure. The A and B stimuli were nonsense syllables, and the C stimuli were sets of "short" or "long" lines. To test for equivalence, Cl or C2 was presented as a sample with Al and A2 as comparisons. Once the class-related comparison was chosen consistently, different line lengths were substituted for the training lines in the CA tests. In general, the likelihood of choosing a given comparison was an inverse function of the difference in the length of the test line from the training line. Stimuli in an equivalence class became functionally related not only to each other but also to novel stimuli that rcsembled a member of the equivalence class. The combination of primary generalization and equivalence class formation, then, can serve as a model to account for the development of naturally occurring categories.