The parenting environment provided by mothers with schizophrenia is likely to contribute to the cognitive impairment observed in their offspring.

To assess the relative contribution of maternal schizophrenia, obstetric factors and mothers' lifestyle to the cognitive development of infants in their first year.

The Bayley Scales of Infant Development were administered to 19 infants of mothers with schizophrenia, 34 with non-psychotic depression in the mother, 29 with affective psychosis in the mother and 24 normal controls when the babies were two and seven months of age.

At two months, infants of mothers with schizophrenia and of those with affective psychosis had lower mental development index (MDI) scores than controls. At seven months, infants of mothers with schizophrenia had lower MDI scores than all other groups. When infant birth weight and mothers' social class were taken into account there was no effect of maternal schizophrenia on infants' MDI scores.

Infants of mothers with schizophrenia are likely to have impaired cognitive development. This may be due in part to environmental factors such as the mother's lifestyle.

We report a survey of the content of obsessions in children with autism spectrum conditions. We use the term obsessions' narrowly, to indicate strong, repetitive interests. We predicted that obsessions would not cluster randomly, but rather would occur significantly more often in the domain of ‘folk physics' (an interest in how things work), and significantly less often in the domain of ‘folk psychology’ (an interest in how people work). These predictions were tested relative to a control group of 33 children with Tourette syndrome.

To examine the content of autistic obsessions, and to test the theory that these reflect an evolved cognitive style of good folk physics alongside impaired folk psychology.

Ninety-two parents returned a questionnaire designed to determine the subject of their child's obsessional interests. The results were analysed in terms of core domains of cognition.

Both predictions were confirmed.

These results suggest that impaired folk psychology and superior folk physics are part of the cognitive phenotype of autism. A content-free theory of obsessions is inadequate.