The present study investigated whether overtraining of the conditional discriminations that are the prerequisites of equivalence class formation strengthens the relations among stimuli in an equivalence class. Two groups of college students formed equivalence classes that consisted of faces that expressed emotions (A) and arbitrary stimuli (B, C, D, and E). The overtraining group had twice as many training trials as the regular training group. For participants who formed equivalence classes, relational strength was evaluated by the generalization of expressed emotions from the A to the D stimuli, which was measured using a semantic differential. An untrained control group showed semantic differential scores that were positive for happy faces, negative for angry faces, and neutral for the D stimuli. For the experimental groups, the D stimuli, when included in equivalence classes, produced scores that were similar to those produced by the equivalent faces. The overtraining group, however, had average values closer to the values of the faces than the regular training group. These results indicate that the amount of training is an experimental parameter that influences the strength of relations between stimuli that are found to be equivalent in matching-tosample tests. Keywords: stimulus equivalence, relatedness of stimuli, overtraining, strength of conditional relations.

Recent research using the event-related potential (ERP) technique has shown that equivalence relations have properties similar to genuine semantic relations. This study aimed to advance electrophysiological investigations of the functional overlap between semantic and equivalence relations. The N400 component, an index of semantic processing, was used to measure whether semantic relations were experimentally established between arbitrary stimuli. The stimuli became equivalent via a matching-to-sample training designed to maximize the establishment of equivalence relations and the strength of the classes. Non-equivalent pairs of stimuli elicited larger N400 responses than equivalent pairs in electrodes placed over the central and parietal scalp regions, providing additional support for the assumption that stimulus equivalence is an appropriate model of semantic relations. Latency of the N400 component was shorter than in previous studies, probably due to experimental parameters that maximized relational strength. These data raise the possibility that N400 latency may provide a continuous measure of relational strength, thus supplementing the all-or-none character of equivalence tests based on matching to sample.

RESUMOComo a análise do comportamento aborda os fenômenos subjetivos? Seria a teoria de eventos privados a única maneira? Guiado por essas questões, o presente trabalho busca apresentar a abordagem dos fenômenos subjetivos na obra de B. F. Skinner, indicando não apenas a teoria de eventos privados, mas também a possibilidade de abordagens alternativas a essa temática, sem referência à privacidade, por exemplo, por meio da magnitude das ações envolvidas nos fenômenos, níveis (aberto e encoberto) do comportamento e conceitos disposicionais. Indica-se ainda uma significativa diferença de ênfase na teoria de eventos privados ao longo da obra skinneriana. Por fim, conduz-se uma discussão sobre o papel da teoria de eventos privados na análise do comportamento para a abordagem dos fenômenos subjetivos.Palavras-chave: fenômenos subjetivos; B. F. Skinner; teoria de eventos privados; explicações disposicionais. ABSTRACT Different approaches to subjective phenomena on B. F. Skinner's workHow do behavior analysis approaches subjective phenomena? Would the private events theory be the only way to do it? Guided by these questions, this paper aims to present the approach to subjective phenomena in B. F Skinner's work, indicating not only the theory of private events but also the possibilities of alternative approaches to this subject, with no reference to privacy, for example, through the magnitude of actions involved in the phenomena, levels of behavior and dispositional concepts. We also indicate a significant difference of emphasis on the private events theory throughout Skinner's work. Finally, we discuss the role of the private events theory in the behavior analysis' approach to subjective phenomena.

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