The cognitive implications of intentional communication: a multifaceted mirror

There is a central concern in contemporary cognitive science with the validity of the use of epistemic and intentional terms to interpret the communication patterns of non-human animals. Here I argue (a) that the human developmental transition to intentional communication is a well-described phenomenon, from an empirical standpoint; (b) that the behavioural patterns that characterise intentional communication in our own species are also well-described in the communication of our nearest living relatives, the great apes; (c) that the presence of the behavioural markers for intentional communication in non-human primates does not unambiguously implicate any particular one of a large number of often mutually contradictory hypothetical psychological process models; and (d) that intentional communication by young humans is also consistent with hypothetical process models that are, themselves, mutually contradictory. Intentional communication is a class of behaviour that is open to public, objective measurement. In contrast, the hypothetical cognitive processes supporting intentional communication in both human and non-human animals are not specified by the fact that intentional communication has occurred—they could not be, except when there is an unambiguous behavioural index of invisible psychological processes, which is a contradiction in terms. In this chapter, I will examine a number of contemporary scientific practices that purportedly reveal aspects of psychological processes underlying intentional communication and demonstrate the deficiencies of these protocols. In general, these methodological infelicities support a systematic, discipline-wide double standard of interpretation of the communication of animals and humans. I will conclude that there is no convincing evidence extant of different psychological processes in the intentional communication of apes and preverbal humans.