Do capuchins (Sapajus apella) know how well they will remember? Analysis of delay length-dependency with memory strategies.

[Correction Notice: An Erratum for this article was reported online in on May 9 2019 (see record 2019-35064-001). Reports several errors in errors in the article: the descriptions of conditions in the Discussion section were incorrect, the number of decimal places for some statistical values was greater, the participants' names were swapped in Tables 1, 2, 3, and 4, and the labels indicating trial types in Figures 3 and 4 were swapped and so did not correctly match the data. All versions of this article have been corrected.] Flexibly changing information processing based on required cognitive resources allows adaptation in terms of cognitive parsimony. Several species have been shown to use temporal durations between memory acquisition and retrieval as a cue for memory-controlling and to engage selectively in active memorization in situations involving lower cognitive cost. However, few studies have addressed whether signaling delay length at different stages of memory affects memorization differently. In the present study with tufted capuchin monkeys (Sapajus apella), we added visual cues signaling upcoming delay length to a delayed matching-to-sample task, so that the monkeys were informed about how long information should be maintained at different points during with-sample or after-sample conditions. We investigated whether the monkeys changed their information processing depending on their expectation of the upcoming delay length and on whether encoding was controllable (4 s vs. 16 s, Experiment 1). The results indicate that two monkeys showed different patterns depending on whether encoding was controllable, whereas the third monkey never changed her strategy. The following experiment using shorter delays showed that one monkey showed a similar pattern across experiments, providing robust evidence for cognitive flexibility in accordance with relative task difficulty (1 s vs. 8 s, Experiment 2). Overall, our results suggest that capuchins adopt two kinds of strategies depending on the experimental context, that is, expending fewer resources on relatively difficult trials and/or maintaining their processing style irrespective of delays. Their strategies aiming at saving cognitive costs may reflect a psychological function to control memory formation either prospectively or retrospectively. (PsycINFO Database Record (c) 2019 APA, all rights reserved).