Getting the Short End of the Stick: Do Chimpanzees Intentionally Attempt to Correct Miscommunications?
Michael J. Kachin, Jamie L. Russell, and William D. Hopkins
Yerkes National Primate Research Center, Division of Psychobiology, Atlanta, GA

Abstract

The study was designed to determine chimpanzees’ capacity to engage in intentional communication and to test their capability to repair failed communicative acts. We tested variation in chimpanzee communicative behaviors based on whether or not they received a usable or non-usable tool to perform a honey dipping task. The results revealed that the chimpanzees engaged in more communicative behaviors after receiving the appropriate tool when compared with the inappropriate tool suggesting an ability to engage in intentional communication.

Introduction

Around the age of 9 months the human infant makes the transition from non-directional acts to intentional communication (Butterworth 2002). Preliminary results suggest that adult chimpanzees display this same intentionality by increasing the frequency and complexity of their communication in an attempt to acquire a more desired food (Leavens submitted). The current study is an extension of the Leavens et. al. study via a “honey dipping” tool task.

Methods and Materials

A total of 38 adult chimpanzees (15 males and 23 females) housed at the Yerkes National Primate Research Center completed the study. All chimpanzees were acclimated to a “honey dipping” apparatus in which the chimps could feed by dipping sticks into a series of honey filled tubes. The apparatus was attached to each enclosure prior to testing. The study consisted of a control and 2 experimental conditions counterbalanced across subjects. The control condition proceeded each experimental condition. Control- the researcher sat 1m outside the subject’s enclosure holding a set of useable tools and observed for 3 min. Correct Tool- the subject was given a large usable stick and then observed for 3 min by the researcher who remained seated in front of the enclosure holding a set of useable tools. Incorrect Tool- the subject was given a small non-usable stick and then observed for 3 minutes by the researcher who remained seated in front of the enclosure holding a set of useable tools. The following communicative behaviors were recorded: gesture vocalization gesture + vocalization cage-bang hoot spit throw lip-pout display clap and barter.

Results

The chimpanzees communicated significantly faster after given the incorrect tool when compared to the correct tool during the post-tests (t (37) = 2.227 p < .05). (figure 1) The chimpanzees communicated more frequently after given the incorrect tool when compared with the correct tool during post-tests (Wilcoxon Signed Ranks Test z = -.3.017 p < .05). (figure 2) After failing to receive the correct tool the chimpanzees’ elaborated on their communicative style during the post-tests (Wilcoxon Signed Ranks Test z = -2.012 p < .05). (figure 3)

Conclusions and Future Studies

Implementing methodology different from that of Leavens allowed us to address the same question from a new angle. By demonstrating that the chimpanzees communicate faster more frequently and elaborate on their communicative style the current study supports previous work by Leavens. Overall results confirm the notion that chimpanzees understand the influence of their own behavior on others and thus have the capacity to correct miscommunications.

Acknowledgements and Funding Attributions

Butterworth G. (2001). Joint Visual Attention in Infancy. In J.G. Brenner and A. Fogel (Eds.) Blackwell Handbook of Infant Development. Hove: Blackwell. Leavens D. Russell J. & Hopkins W. Repair of Failed Communication by Chimpanzees. (submitted). The preceding research was funded by the Howard Hughes Medical Institute.