Extraction of structural regularities by baboons (Papio Papio): Adjacent and nonadjacent repetition patterns differ in learnability.

Several animal species can discriminate between different sequential patterns based on repetitions of items (e.g., ABB vs. ABA), and generalize their performance to sequences made of novel elements but following the same underlying structure. This achievement suggests that these species possess the ability to abstract the sequences structures beyond exemplars. Developmental studies in humans suggest however that adjacent repetition patterns (e.g., ABB) are easier to extract than patterns based on a nonadjacent (e.g., ABA) repetitions. This study addressed this effect of adjacency from a comparative perspective. Seventeen Guinea baboons () were tested with an adaptation of the serial response time task. Results show that baboons successfully learned and generalized both adjacent and nonadjacent repetition patterns after extensive exposure to each pattern in 2 successive experimental phases (Experiment 1). However, when these patterns were presented interleaved within the same experimental phase and at equal frequencies (Experiment 2), or presented successively as in Experiment 1 but with less exposure trials (Experiment 3), baboons showed evidence of learning of the adjacent repetition pattern only. Overall, these data suggest that baboons are more sensitive to adjacent than nonadjacent repetitions. We argue that a strategy based on sole detection of the presence/absence of an adjacent repetition is therefore likely to be adopted by the tested animals in pattern learning studies contrasting adjacent versus nonadjacent repetition patterns, and that future studies may need to avoid this contrast to prevent the use of this strategy. (PsycInfo Database Record (c) 2021 APA, all rights reserved).