Discrimination Learning in the Armadillo (Chaetophractus villosus): A Study of Positional Strategies

Abstract

Choice behavior of the armadillo Chaetophractus villosus (Edentata, Dasypodidae) was studied under laboratory conditions. Two groups were trained in a simultaneous visual discrimination task with food-reward. One group was trained with a contiguous spatial-temporal relationship between the discriminative stimulus and the reinforcement. For the second group, a spatial-temporal separation of these relevant stimuli was imposed in order to lengthen the presolution period. Attention was directed at determining which one of four positional strategies (alternation, position habit, win-shift/lose-stay, and win-stay/lose-shift) prevailed during the acquisition of the discrimination. There were no obvious differences in choice strategies between the groups, although the immediate spatial-temporal contiguity between the discriminative and reinforcing stimuli produced a significantly faster acquisition. Position habit was the only spatial strategy consistently observed between animals and maintained for a variable number of successive sessions in a given subject. The information gathered in this experiment is related to learning processes and the possible adaptive significance of choice strategies.