Pareamento ao modelo com atraso em Cebus cf. apella: efeitos da manipulação do atraso e do intervalo entre tentativas

Abstract

Aimming to develop non-verbal tests of cognitive functions for assessment of deficiencies resulting from mercury contamination in children, the performance in Delayed Matching to Sample (DMTS) was studied in capuchin monkeys, a procedure that has been used to assess short-term memory processes in nonhumans. Studies with nonhumans indicate that choice accuracy deteriorates with delay increase. However, some experiments indicate that the exposure to a new condition of delay or increasing the Intertrial Interval (ITI) can produce recovery of the performance. The objective of this study was a first exploration of the effects of delay and ITI durations on the DMTS performance in two adult male capuchins, Raul and Dracula. Raul performed the arbitrary DMTS task with 10 stimulus relations and Dracula, performed identity DMTS task with 9 stimulus relations. Three-choices trials of all relations were interspersed in the sessions. In a trial, a sample stimulus was presented, five touches on the sample produced its disappearance. After a delay, three comparisons were presented. One touch on the positive comparison produced a banana pellet and the ITI. Responses on the negative stimulus produced only the ITI. After stable performance in 1 s delay and 6 s of ITI sessions, the level of correct answers after successive increases of 0.5 s in the delay was evaluated. When level of correct responses decreased below 80%, the ITI was increased in 1 s. There were two types of session: 1) Fixed Delay - only one delay was programmed for all session trials, and2) Variable Delay - different delays were programmed in session trials. Raul performed 48 ARBDMTS fixed delay sessions, with delays increasing from 1.0 to 5.5 s, in which the performance varied from 50 to 100% correct, and 27 variable delay sessions, with delays increasing from 1.0 to 9.5 s, and the performance varied from 75 to 95% correct. Dracula performed 59 IDDMTS fixed delay sessions, from 1.0 to 13.5 s, with performance between 61 and 100% correct, and 17 IDDMTS variable delay sessions, with delays varying from 1 s to 15 s. Dracula’s overall performance ranged from 72 to 100% correct. For both subjects, performance decreased in sessions whith increase of the delay, performance recovery followed continued training in the same condition alone or with ITI increase. Gradual increase of delay and ITI on 3-choiceIDDMTSand ARBDMTS, was effective to maintain performance level higher than 90% with delays of 15.0 s for Dracula (identity) and 9.5 s for Raul (arbitrary).This study will serve as basis for measuring DMTS performance of capuchin monkeys contaminated with mercury. Subsequently, an equivalent standard test will be used to verify the correlation between measures of repertoire and the degree of mercury contamination in children.