Chimpanzee Use of Human and Conspecific Social Cues to Locate Hidden Food

Abstract

Two studies are reported in which chimpanzees attempted to use social cues to locate hidden food in one of two possible hiding places. In the first study four chimpanzees were exposed to a local enhancement cue (the informant approached and looked to the location where food was hidden and then remained beside it) and a gazeapoint cue (the informant gazed and manually pointed towards the location where the food was hidden). Each cue was given by both a human informant and a chimpanzee informant. In the second study 12 chimpanzees were exposed to a gaze direction cue in combination with a vocal cue (the human informant gazed to the hiding location and produced one of two different vocalizations: a`food-bark' or a human word-form). The results were: (i) all subjects were quite skillful with the local enhancement cue, no matter who produced it; (ii) few subjects were skillful with the gazeapoint cue, no matter who produced it (most of these being individuals who had been raised in infancy by humans); and (iii) most subjects were skillful when the human gazed and vocalized at the hiding place, with little difference between the two types of vocal cue. Findings are discussed in terms of chimpanzees' apparent need for additional cues, over and above gaze direction cues, to indicate the presence of food.

Cooperation and human cognition: the Vygotskian intelligence hypothesis

“…Not one of six chimpanzees used this cue to find the food. Tomasello et al (1997a) and Call et al (2000) provided chimpanzees with several other types of visual-gestural cues (including pointing) in this same paradigm and also found mostly negative results (see also Itakura et al 1999;Povinelli et al 1999).…”

“…After this 'warm-up', the hider again places a piece of food in one of the containers, but now the helper indicates the location of the food for the ape by pointing at the baited container with his index finger (or by gazing at it). Variations of this method involve other kinds of communicative cues ) and a trained chimpanzee instead of a human as the provider of the cue (Itakura et al 1999). The results were the same in all these studies: the apes performed poorly, that is, they chose the correct container at chance level.…”

All Great Ape Species Follow Gaze to Distant Locations and Around Barriers.

“…The discrepancy between being able to follow human gaze but not being able to use it to select the baited container is puzzling Itakura et al, 1999). One possible explanation for this discrepancy is that a simple gaze cue by itself is not enough to suggest the presence of food in the gazed-at locations.…”

Chimpanzees are more skilful in competitive than in cooperative cognitive tasks

“…Call & M. Tomasello, unpublished data), food was not hidden in the same hiding location for more than two trials in a row (including in the introduction of the current experiment). When subjects cannot find food reliably, they frequently develop an optimizing strategy in which they exclusively choose the same cup (Itakura et al 1999). By repeatedly choosing the same cup they are assured of (1) going no more than two trials without finding food and (2) finding food in half the trials (assuming side is counterbalanced).…”

“…Povinelli et al (1999) found that some chimpanzees could learn to use similar cues after several dozen trials, but they also showed in various ways that this was for them only a learned behavioural cue, not an indicator of the visual experience of others; for example, when the experimenter turned his head in the direction of the baited container but looked to the ceiling, subjects chose the correct container just as often as if the experimenter looked directly at it. Itakura et al (1999) used a trained chimpanzee conspecific to give the gaze direction cue, but still found mostly negative results. Other primate species also take dozens or scores of trials to learn to use human social cues in the object choice paradigm (Anderson et al 1995;Vick et al 2001;Neiworth et al 2002).…”