Self-recognition, Theory-of-Mind, and self-awareness in primates and right hemispheres

A fashionable view in comparative psychology states that primates possess self-awareness because they exhibit mirror self-recognition (MSR), which in turn makes it possible to infer mental states in others (“Theory-of-Mind”; ToM). In cognitive neuroscience, an increasingly popular position holds that the right hemisphere represents the center of self-awareness because MSR and ToM tasks presumably increase activity in that hemisphere. In this chapter I critically assess these two claims as follows. MSR should not be equated with full-blown selfawareness; for instance, evidence suggests that MSR only requires kinesthetic self-knowledge and does not involve access to one’s mental events. ToM and self-awareness are fairly independent and should also not be taken as equivalent notions; to illustrate, ToM implies a focus of attention on others, not on the self, whereas self-awareness exclusively entails self-focus. MSR and ToM tasks engage medial and left brain areas—not sites solely located in the right hemisphere, as recent meta-analyses of brain-imaging studies clearly show. Other selfawareness tasks besides MSR and ToM tasks (e.g., self-description, autobiography) mostly recruit medial and left brain areas. And inner speech, produced by the left hemisphere and which primates lack, plays a significant role in self-referential activity; indeed, accidental loss of inner speech following brain injury leads to self-awareness deficits. The conclusions I will reach based on this analysis is that (1) primates that display MSR most probably do not possess introspective self-awareness, and (2) self-related processes most likely engage a distributed network of brain regions situated in both hemispheres.