Electrophysiological Correlates of Stimulus Equivalence Processes

Abstract

Research reported here concerns neural processes relating to stimulus equivalence class formation. In Experiment 1, two types of word pairs were presented successively to normally capable adults. In one type, the words had related usage in English (e.g., uncle, aunt). In the other, the two words were not typically related in their usage (e.g., wrist, corn). For pairs of both types, event-related cortical potentials were recorded during and immediately after the presentation of the second word. The obtained waveforms differentiated these two types of pairs. For the unrelated pairs, the waveforms were significantly more negative about 400 ms after the second word was presented, thus replicating the "N400" phenomenon of the cognitive neuroscience literature. In addition, there was a strong positive-tending wave form difference post-stimulus presentation (peaked at about 500 ms) that also differentiated the unrelated from related stimulus pairs. In Experiment 2, the procedures were extended to study arbitrary stimulus-stimulus relations established via matching-to-sample training. Participants were experimentally naïve adults. Sample stimuli (Set A) were trigrams, and comparison stimuli (Sets B, C, D, E, and F) were nonrepresentative forms. Behavioral tests evaluated potentially emergent equivalence relations (i.e., BD, DF, CE, etc.). All participants exhibited classes consistent with the arbitrary matching training. They were also exposed also to an event-related potential procedure like that used in Experiment 1. Some received the ERP procedure before equivalence tests and some after. Only those participants who received ERP procedures after equivalence tests exhibited robust N400 differentiation initially. The positivity observed in Experiment 1 was absent for all participants. These results support speculations that equivalence tests may provide contextual support for the formation of equivalence classes including those that emerge gradually during testing.

Electrophysiological investigation of the functional overlap between semantic and equivalence relations.

“…Nevertheless, it is still possible to contrast our ERP data with those presented in previous works that reported similar findings in order to discuss a possible role that the ERP technique may play in stimulus equivalence research. An interesting difference emerges by contrasting our data with those reported by Barnes-Holmes et al (2005) and Haimson et al (2009) regarding the latency for the achievement of N400 responses. Visual inspection of the waveforms presented by both Barnes-Holmes et al (2005, Fig.…”

Learning processes and the neural analysis of conditioning.

“…This datum indicated that responding (silently judging) to stimulus pairs favored equivalence class formation. Thus, Haimson et al (2009) indicated that non-reinforced presentation of related and unrelated pairs might have the same effect of non-reinforced matchingto-sample testing. So the existence of a context of testing, regardless of whether it involves the matching-to-sample, is probably necessary for the emergence of equivalence relations, as Sidman (1994) argued.…”

Estabelecimento E Reorganização De Relações Arbitrárias Derivadas Após O Treino Em Matching-to-Sample De Identidade Com Consequências Específicas

“…Estes resultados podem ser interpretados como evidências de emergência atrasada, na medida em que a experiência prévia com relações arbitrárias no procedimento MTS parece influenciar os desempenhos nas tentativas que testam relações de equivalência (cf. Dube et al, 1987Dube et al, , 1989Dube & McIlvane, 1995;Haimson, Wilkinson, Rosenquist, Ouimet, & McIlvane, 2009). …”