From colour photographs to black-and-white line drawings: an assessment of chimpanzees’ (Pan troglodytes’) transfer behaviour

Abstract

Over two experiments, we investigated the ability of two adolescent and two adult chimpanzees to generalise a learnt, pictorial categorisation to increasingly degraded and abstract stimuli. In Experiment 2, we further assessed the ability of the adolescent chimpanzees to engage in open-ended categorisation of black-and-white line drawings. The current results confirmed and extended previous findings, showing that sub-adult chimpanzees outperform adult chimpanzees in the categorisation of pictorial stimuli, particularly when the stimuli are more degraded and abstract in nature. However, none of the four chimpanzees showed positive transfer of their category learning to a set of black-and-white line drawings, and neither of the adolescent chimpanzees evidenced reliable open-ended categorisation of the black-and-white line drawings. The latter findings suggest that both sub-adult and adult chimpanzees find it difficult to recognise black-and-white line drawings, and that open-ended categorisation of black-and-white line drawings is challenging for chimpanzees.

Pictorial Competence in Primates: A Cognitive Correlate of Mirror Self-Recognition?

“…However, the adolescent chimpanzees finally learned to categorize line drawings after a moderate period of training. These findings are broadly consistent with those of Tanaka [75], as after training, juvenile chimpanzees, unlike naïve adults, similarly showed in [75] and in [78] positive transfer of their previous category learning (colored pictures) to the degraded stimuli (black and white pictures or line drawings). Overall, it suggests that learning abilities may be enhanced by training during a critical period of chimpanzees' development that further enables adults to achieve various cognitive tasks.…”

“…Actually, training regimen with pictorial display seems to influence drastically primates' behavioral responses. Untrained chimpanzees either failed to match real objects with their pictures when the objects were previously explored haptically [63] or to match real objects with line drawings of objects [75,78]. It is only after training with degraded pictures that an equivalence mode of picture processing gradually emerged, at least in juveniles in these studies [75,78].…”

“…Their good performance may be due to their better learning ability, as it is established that young animals show greater cognitive flexibility, for example [76,77]. Close and Call [78] used a similar procedure with sub-adult and adult naïve chimpanzees. The subjects were presented with colored, black and white sketches, and line drawings of the training pictures (tree vs. flower).…”

“…Untrained chimpanzees either failed to match real objects with their pictures when the objects were previously explored haptically [63] or to match real objects with line drawings of objects [75,78]. It is only after training with degraded pictures that an equivalence mode of picture processing gradually emerged, at least in juveniles in these studies [75,78]. A similar experiment with macaques trained to match objects and their pictures, and only when they were visible at the same time, also resulted in successful objects/pictures matching [79,80].…”

Similar stimulus features control visual classification in orangutans and rhesus monkeys

“…Many organisms generalize and discriminate in ways that at least approximate classification of images (Brown & Boysen, ; Close & Call, ; D'Amato & Van Sant, ; Herrnstein & Loveland, ; Koba & Izumi, ; Spencer, Quinn, Johnson, & Karmiloff‐Smith, ; Zentall, Wasserman, Lazareva, Thompson, & Rattermann, ). For example, several species successfully assign stimuli to groups by making specific responses when presented with images belonging to the groups (Basile & Hampton, ; Gazes, Brown, Basile, & Hampton, ; Hayes & Nissen, ; Schrier, Angarella, & Povar, ; Wasserman, Kiedinger, & Bhatt, ).…”