Case Study 11a

Chimpanzees (Pan troglodytes) exhibit gaze bias for snakes upon hearing alarm calls.

“…Food-associated calls have been reported to attract other chimpanzees to a food patch, at least in some cases (Kalan & Boesch, 2015; O’Bryan et al, 2021; but see O’Bryan, 2015 for a null result). In particular, chimpanzee food grunts have been suggested to exhibit different acoustic profiles depending on the characteristics of food, such as the relative value/preference or size of the food (Hallberg et al, 2003; Kalan et al, 2015 [but only for one tree species]; Slocombe & Zuberbühler, 2005, 2006 [in captivity but not in a wild habitat]; see also O’Bryan, 2015 for a null result). Preliminary evidence suggests that audience chimpanzees may use such acoustic differences to guide subsequent behaviors (Kalan et al, 2015; Slocombe & Zuberbühler, 2005).…”

“…Preliminary evidence suggests that audience chimpanzees may use such acoustic differences to guide subsequent behaviors (Kalan et al, 2015; Slocombe & Zuberbühler, 2005). Similarly, when captive chimpanzees were presented with four images of different food items on a touchscreen and heard a playback of food barks, chimpanzees were reported to spontaneously select an image depicting a food item of similar value as the one that elicited the food bark more often than expected by chance (Hallberg et al, 2003; Gibbons, 2007). However, this line of inquiry has yielded mixed results (O’Bryan, 2015), and the cognitive underpinnings of audience behavioral responses to those calls remain unclear.…”

Primate Cognition Redux

“…His review omits significant work on the referential quality of monkey calls [e.g., Gouzoules et al, 1984] that goes well beyond the early paradigmatic work of Cheney and Seyfarth detailed by Gomez. Other relevant work, such as that by Hallberg et al [2003] demonstrating the referential quality of chimpanzee food barks, may have appeared too late for inclusion in the book.…”