Scratching beneath the surface: intentionality in great ape signal production

Abstract

Despite important similarities having been found between human and animal communication systems, surprisingly little research effort has focussed on whether the cognitive mechanisms underpinning these behaviours are also similar. In particular, it is highly debated whether signal production is the result of reflexive processes, or can be characterized as intentional. Here, we critically evaluate the criteria that are used to identify signals produced with different degrees of intentionality, and discuss recent attempts to apply these criteria to the vocal, gestural and multimodal communicative signals of great apes and more distantly related species. Finally, we outline the necessary research tools, such as physiologically validated measures of arousal, and empirical evidence that we believe would propel this debate forward and help unravel the evolutionary origins of human intentional communication. This article is part of the theme issue ‘What can animal communication teach us about human language?’

What can animal communication teach us about human language?

“…Graham et al [24] critically evaluate the criteria used to identify the degree of intentionality in a signal and how the criteria are applied to animal, especially primate, communication. They emphasize the difficulty of differentiating between zero-order intentionality (in which an animal vocalizes with no intention of communicating to others, and no mentality is involved in signalling) and first-order intentionality (where the signaller intends to signal in order to alter the behaviour of the recipient).…”

Exploring the cerebral substrate of voice perception in primate brains

“…Two others employed vocal-to-facial matching tasks and reported correct identification of the caller from both long-range and short-range calls [79,80]. In contrast with this sparse literature on CV perception, higher-level properties of communication like intentionality and meaning have been described for chimpanzee vocalizations [15,17].…”

Intentional communication: solving methodological issues to assigning first‐order intentional signalling

“…However, recent evidence for intentional vocal communication in chimpanzees (Pan troglodytes) questions this idea (Liebal et al, 2014;Schel et al, 2013). This controversy emphasises the urgent need to improve methodologies distinguishing between non-intentional signalling and even basic forms of intentionality to allow valid comparisons across species and communicative modalities (Townsend et al, 2017;Graham et al, 2019).…”

“…Intentional signalling in the sense that is used in comparative psychology is, therefore, a prerequisite for the intentional and ostensive communication that are discussed in developmental psychology and philosophy (Coggins & Carpenter, 1981;Liebal et al, 2014). As efforts are still being made to distinguish reliably between nonintentional and intentional signalling in animals (Townsend et al, 2017;Graham et al, 2019), the current paper focusses on the more fundamental level of intentional signalling.…”

“…(3) Obstacles to inference and systematic comparison of first-order intentional signalling Three main obstacles hinder valid inference and systematic comparison of intentionality in animals. First, inconsistency in how hallmarks of intentionality are defined and operationalised prevents systematic comparison among studies, species and communicative modalities (Liebal et al, 2014;Graham et al, 2019). Progress toward uniformity has recently been made in the framework developed by Townsend et al (2017).…”