Meta-analysis provides qualified support for increased semantic priming as a psychological abnormality underlying thought disorder. However, the possibility that the effect is an artefact of general slowing of reaction time in schizophrenia has not been excluded.

It has been suggested that formal thought disorder, the incoherent speech of schizophrenia, may involve a language disturbance among other abnormalities, or even be a form of dysphasia. Six patients with and seven without formal thought disorder were evaluated on an aphasia test battery. Spontaneous speech was also analysed using Brief Syntactic Analysis. Poor performance on the aphasia test battery was found to be associated with general intellectual impairment but not with formal thought disorder. Naming was preserved in both groups. Patients with formal thought disorder, but not those without, produced semantic errors in their spontaneous speech, and these were unrelated to general intellectual status. The disorder of language in formal thought disorder thus appears to be one of expressive semantic abnormality, which, however, spares naming. Further analysis of two intellectually preserved patients suggested that formal thought disorder may be associated with an additional difficulty in constructing an appropriate model for generating one's own speech.

The absence of activation in the right posterior temporal and left superior frontal cortex in patients with schizophrenia might contribute to the articulation of grammatically more simple speech in people with this disorder.

No abstract

The differences between voices are often broadly categorized as either 'organic' or 'learned', implying that some are determined by our anatomical inheritance, and others by what we copy from people around us or choose in order to mark our individuality. It is normally impossible, however, to assign observable differences to one source or the other, since neither source is experimentally controllable. In the case of identical twins, nature provides such a control. It can reasonably be assumed that the anatomical differences within a pair of identical twins are minimal. Differences between their voices, if any, may be attributed to 'learning' and, furthermore, if the twins have grown up in the same environment, to choices rather than to direct imitation. This paper presents a study of the /l/ and /r/ phonemes of three pairs of identical twins.