Hypothesis analysis of sameness-difference learning-set by capuchin monkeys

Sameness-difference discriminations were presented to capuchin monkeys and hypothesis analysis was applied to the data. Learners and nonlearners evidenced differences in overall performance and in relative strengths of hypotheses. Learners initially displayed markedly more random than position responding whereas nonlearners evidenced more position than random responding and remained particularly prone to position habits. Stimulus preference and aversion, suppressed by learners by the end of training, reemerged at the onset of two-object discriminations containing previously preferred and aversive stimuli. Hypothesis analysis indicated that when preferred stimuli were positive the correct hypothesis was more evidenced, and stimulus preference or aversion as well as random hypotheses were less evidenced, than when aversive stimuli were positive.