Social cognition, language acquisition and the development of the theory of mind

Theory of Mind (ToM) is the cognitive achievement that enables us to report our propositional attitudes, to attribute such attitudes to others, and to use such postulated or observed mental states in the prediction and explanation of behavior. Most normally developing children acquire ToM between the ages of 3 and 5 years, but serious delays beyond this chronological and mental age have been observed in children with autism, as well is in those with severe sensory impairments. We examine data from Studies of ToM in normally developing children and those with deafness, blindness, autism and Williams syndrome, as well as data from lower primates, in a search for answers to key theoretical questions concerning the origins, nature and representation of knowledge about the mind. In answer to these, we offer a framework according to which ToM is jointly dependent upon language and social experience, and is produced by a conjunction of language acquisition with children's growing social understanding, acquired through conversation and interaction with others. We argue that adequate language and adequate social skills are jointly causally sufficient, and individually causally necessary, for producing ToM. Thus our account supports a social developmental theory of the genesis of human cognition, inspired by the work of Sellars and Vygotsky.

Complex language functions and subcortical mechanisms: evidence from Huntington's disease and patients with non-thalamic subcortical lesions

The neuropathological changes associated with Huntington's disease (HD) are most marked in the head of the caudate nucleus and, to a lesser extent, in the putamen and globus pallidus, suggesting that at least part of the language impairments found in patients with HD may result from non-thalamic subcortical (NTS) pathology. The present study aimed to test the hypothesis that a signature profile of impaired language functions is found in patients who have sustained damage to the non-thalamic subcortex, either focally induced or resulting from neurodegenerative pathology. The language abilities of a group of patients with Huntington's disease (n=13) were compared with those of an age- and education-matched group of patients with chronic NTS lesions following stroke (n=13) and a non-neurologically impaired control group (n=13). The three groups were compared on language tasks that assessed both primary and more complex language abilities. The primary language battery consisted of The Western Aphasia Battery and The Boston Naming Test, whilst the more complex cognitive-linguistic battery employed selected subtests from The Test of Language Competence-Expanded, The Test of Word Knowledge and The Word Test-Revised. On many of the tests of primary language function from the Western Aphasia Battery, both the HD and NTS participants performed in a similar manner to the control participants. The language performances of the HD participants were significantly more impaired (p<0.05 using modified Bonferroni adjustments) than the control group, however, on various lexico-semantic tasks (e. g. the Boston Naming Test and providing definitions), on both single-word and sentence-level generative tasks (e. g. category fluency and formulating sentences), and on tasks which required interpretation of ambiguous, figurative and inferential meaning. The difficulties that patients with HD experienced with tasks assessing complex language abilities were strikingly similar, both qualitatively and quantitatively, to the language profile produced by NTS participants. The results provide evidence to suggest that a signature language profile is associated with damage to the non-thalamic subcortex resulting from either focal neurological insult or a degenerative disease.