Distal Communication by Chimpanzees (Pan troglodytes): Evidence for Common Ground?

Abstract

van der Goot et al. (2014) proposed that distal, deictic communication indexed the appreciation of the psychological state of a common ground between a signaler and a receiver. In their study, great apes did not signal distally, which they construed as evidence for the human uniqueness of a sense of common ground. This study exposed 166 chimpanzees to food and an experimenter, at an angular displacement, to ask, “Do chimpanzees display distal communication?” Apes were categorized as (a) proximal or (b) distal signalers on each of four trials. The number of chimpanzees who communicated proximally did not statistically differ from the number who signaled distally. Therefore, contrary to the claim by van der Goot et al., apes do communicate distally.

Prelinguistic human infants and great apes show different communicative strategies in a triadic request situation

“…Unlike infants, however, the reward location also influenced apes’ signaling on the experimenter’s side and they exhibited a predominant preference to gesture visually at the reward location. This result supports the findings of van der Goot et al [46] and Leavens et al [45]. Van der Goot et al [46] showed that chimpanzees always approached the desired item as close as possible before signaling their request, whereas the 12 month old infants continued to point from the distance even when they could have retrieved the reward themselves.…”

“…Likewise, in the current study, the apes in the TS condition almost exclusively signaled on the side with the reward (and the experimenter). Leavens et al [45] found no preference within their sample of chimpanzees to signal in close proximity to the reward in a setting where the experimenter and the reward were in different locations, while we found such a preference in the TD condition. This might be due to differences in the coding protocols across the two studies, since we coded and compared participants’ positioning in relation to the middle line that split the experimental area in half (with experimenter and reward being positioned equally distant from the middle).…”

“…This might be due to differences in the coding protocols across the two studies, since we coded and compared participants’ positioning in relation to the middle line that split the experimental area in half (with experimenter and reward being positioned equally distant from the middle). However, Leavens et al [45] compared signals produced in close proximity of the reward to the summed signals produced close to the experimenter and anywhere else in-between those two extreme positions.…”

“…One of the goals of the study was to investigate whether apes and infants exhibit a preference to signal in close proximity to the reward [46] or whether they show no such preference [45]. Therefore we explored for each condition whether participants spent more time or produced more auditory and visual gestures on the experimenter’s side or on the other side.…”

“…Yet, due to the repeated turn-taking and communicative interactions with the human, it remains unclear whether the apes were attempting to direct the human’s attention towards the food (or were just responding to behavioural and positional cues to maneuver the human to the reward location). Furthermore the results of the only other study investigating apes’ communication in a situation in which food and experimenter were at separate locations [45] are difficult to compare to other studies (e.g. [46]).…”