Ana Leda de Faria Brino

Extent and limits of the matching concept in Cebus apella: A matter of experimental control?

The capacity to exhibit generalized sameness-difference judgments is a hallmark of cognition that is regularly exhibited by humans. As yet, that capacity has not been well documented in New World monkeys such as the capuchin (Cebus apella). This article presents data obtained with 6 capuchin monkeys with a variety of procedures that might lead to generalized identity matching-to-sample (MTS) in this species, reporting part of a research program conducted to evaluate methods for assessing the species’ relational learning capacity. Our working hypothesis is that past failures to demonstrate relational learning have been caused by procedural insufficiency rather than a lack of capacity. Thus far, 6 capuchin monkeys have been test,ed for generalized identity MTS. The apparatus was a touchscreen-equipped microcomputer-controlled experimental chamber. Eleven sets of 3 visual stimuli (black shapes on gray backgrounds) were used. The general procedure was comprised of 4 phases: (a) simple discriminations, (b) repeated shifts of simple discriminations, (c) identity MTS training, and (d) generalized identity MTS tests. Every subject was exposed to each of the phases. Positive results on generalized identity MTS tests were obtained in all of the animals, although there have been substantial differences across individuals. The animal tested most recently has performed at levels comparable to typically developing preschool children.

Sample Stimulus Control Shaping and Restricted Stimulus Control in Capuchin Monkeys: A Methodological Note.

This paper reports use of sample stimulus control shaping procedures to teach arbitrary matching-to-sample to 2 capuchin monkeys (Cebus apella). The procedures started with identity matching-to-sample. During shaping, stimulus features of the sample were altered gradually, rendering samples and comparisons increasingly physically dissimilar. The objective was to transform identity matching into arbitrary matching (i.e., matching not based on common physical features of the sample and comparison stimuli). Experiment 1 used a two-comparison procedure. The shaping procedure was ultimately effective, but occasional high error rates at certain program steps inspired a follow-up study. Experiment 2 used the same basic approach, but with a three-comparison matching task. During shaping, the monkey performed accurately until the final steps of the program. Subsequent experimentation tested the hypothesis that the decrease in accuracy was due to restricted stimulus control by sample stimulus features that had not yet been changed in the shaping program. Results were consistent with this hypothesis, thus suggesting a new approach that may transform the sample stimulus control shaping procedure from a sometimes useful laboratory tool to a more general approach to teaching the first instance of arbitrary matching performances to participants who show protracted difficulties in learning such performances.

Expansão de repertório de relações arbitrárias em Sapajus sp. via exclusão

The procedure of exclusion may expand children’s repertoire of arbitrary relations resulting in errorless learning, but although choice by exclusion has been reported in a variety of species, it is not followed by learning of the new relations. The objective of this paper was to verify if capuchins would choose by 1 Endereço para correspondência: Escola Experimental de Primatas, Núcleo de Teoria e Pesquisa do Comportamento, Universidade Federal do Pará, Rua Augusto Corrêa, n° 1, Guamá, Belém, PA, Brasil 66075-110. E-mail: rodolfo.s.campos@gmail.com Trabalho apresentado em sessão coordenada “Responder por exclusão: das abelhas aos universitários, o que aprendemos?”, na XLI Reunião Anual da Sociedade Brasileira de Psicologia, 2011, Belém, PA. Os três autores participam do Instituto Nacional de Ciência e Tecnologia Sobre Comportamento, Cognição e EnsinoINCT/ECCE (Processo Fundação de Amparo à Pesquisa do Estado de São Paulo [FAPESP] 08/577058; Processo Conselho Nacional de Desenvolvimento Científi co e Tecnológico [CNPq] 573972/2008-7). Campos, R. S., Brino, A. L. F., Galvão, O. F. 32 exclusion, and if they subsequently would acquire the new arbitrary relations as outcome of exclusion. The capuchin monkey had previously acquired a repertory of 5 A-B and their symmetric B-A arbitrary relations in delayed-matching to-sample (DMTS) with fi ve or more choices. Using a two-choice DMTS, new A-C relations were introduced using non paired B stimuli as Sto verify exclusion. The subject excluded non paired B and chose the new C stimuli. However, performance was disrupted in trials with only C stimuli as comparisons; training with a blank stimulus substituting either comparison in turns was ineffective. Further studies using trials with more than two comparison stimuli will verify arbitrary relations’ learning in capuchins after exclusion.

Stimulus equivalence and N400 in poststroke patients: An exploratory study.

Stroke is caused by an abnormality in brain blood circulation. Approximately 30% of patients present cognitive impairment after brain damage. N400 is an electrophysiological wave that has been related to semantic tasks and the equivalence test. This study’s objectives were to (a) compare the learning of conditional relations and the formation of equivalence classes in patients with stroke with and without cognitive impairment and (b) verify N400’s occurrence and quality under different conditions of stimulation. Two experiments were conducted with 9 participants each, divided into 3 groups: control group, healthy adults; Experimental Group 1, patients with stroke and no cognitive impairment; and Experimental Group 2, patients with stroke patients and cognitive impairment. In Study 1, 9 participants were taught arbitrary conditional relations and equivalence tests. In Study 2, electrophysiological records were made in addition to teaching the conditional relations protocol. The arbitrary conditional relations teaching protocol was efficient, and the equivalence class formation was documented for the control group and Experimental Group 1 but not for Experimental Group 2. In Study 2, Participants P21, P22, and P24 presented the N400 wave’s occurrence in 4 stimulation conditions; P26 in 3 stimulation conditions; P27 and P29 in none of the conditions. The amount of learning and equivalence class formation was directly related to the N400 wave’s quality and occurrence. This corroborates the results from other studies that found that emergent conditional stimulus relations can be considered semantic.

Simple discrimination by exclusion in infant capuchin monkeys.

Learning by exclusion in capuchin monkeys is reported. Two infant female capuchin monkeys were tested for control of choices by exclusion and by novelty and for incorporation of novel stimuli into functional classes after establishment of a robust baseline for exclusion in a 2-choice simultaneous simple discrimination task including 4 positive and 4 negative stimuli. Control by exclusion was assessed by substituting novel stimuli for familiar baseline positive stimuli, resulting in 16 stimulus pairs of combinations of 4 novel stimuli and 4 negative stimuli. Control by novelty was assessed by replacing new stimuli for baseline negative stimuli while maintaining the positive stimuli from the exclusion phase. Finally, the learning of new simple discriminations by exclusion was assessed by replacing novel stimuli with the 4 familiar negative stimuli used in the previous exclusion test. Both subjects demonstrated control by exclusion but not by novelty. One subject learned new stimulus functions without errors after exposure to very few training trials in the exclusion context, consistent with the “fast mapping” phenomenon.

INTERFERÊNCIA DE CONTROLE PELA POSIÇÃO DO ESTÍMULO EM TREINO DE DISCRIMINAÇÕES CONDICIONAIS ARBITRÁRIAS EM MACACO-PREGO (Sapajus sp.)

A interferencia do controle pela posicao dos estimulos no treino de discriminacoes condicionais ja foi documentada na literatura sobre controle de estimulos com animais. Estudos subsequentes sugeriram (1) a introducao da variacao da posicao do estimulo modelo e (2) a ampliacao da variacao da posicao dos estimulos de comparacao. O presente estudo documenta a interferencia do controle pela posicao dos estimulos mesmo nessas condicoes de grande variacao da posicao dos estimulos no treino. Foi utilizado o procedimento de matching-to-sample arbitrario com atraso zero com um macaco-prego (Sapajus sp.). A posicao dos estimulos modelo e de comparacao, apresentados na tela sensivel ao toque de um computador, variava a cada tentativa, podendo assumir qualquer uma das nove posicoes de uma matriz 3x3. Durante o treino, foram observados erros sistematicos nas configuracoes em tentativas em que a comparacao correta (S+) se localizava nas posicoes 8 ou 9. Manipulacoes nas posicoes nas quais o S+ era apresentado confirmaram a interferencia do controle pela posicao. E provavel que esse tipo de interferencia esteja envolvido em boa parte dos fracassos obtidos em estudos visando demonstrar identidade generalizada e a formacao de classes de equivalencia em nao-humanos. Palavras-chave: relacoes de controle de estimulos, discriminacoes condicionais arbitrarias, Sapajus sp.