Can squirrel monkeys learn an AB n A grammar? A re-evaluation of Ravignani et al. (2013)

Ravignani et al. (2013) habituated squirrel monkeys to sound sequences conforming to an AB n B grammar, then tested them for the ability to identify novel grammatical sequences as well as non-grammatical ones. Although they conclude that the monkeys "consistently recognized and generalized the sequence AB n A," the data indicate very poor generalization. Pattern grammaticality accounted for at most 6% of the variance in responding. In addition, the statistical significance of results depends on specific choices of data analysis (dichotomization of the response variable and omission of certain data points) which appear to have a weak rationale. I also suggest that the task used by Ravignani et al. (2013) may be fruitfully analyzed as an auditory sequence discrimination task that does not require specific proto-linguistic abilities.