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Introduction: Delays in theory of mind (ToM) of children who are congenitally blind have often been attributed to the absence of visual and social experiences. However, these delays could also be partly due to neural factors. In some children, the blindness itself has neural causes (ocular-plus blindness). Children whose blindness has an ocular-plus cause may be more delayed in ToM than children with blindness due to ocular causes. Methods: In the current study, performances of children with congenital ocular-plus blindness (n = 22) and congenital ocular blindness (n = 9) were compared with sighted children (n = 103) on ToM tasks designed for children with blindness. Results: Compared with sighted children, ToM performance was delayed in children with ocular-plus blindness, but not in children with ocular blindness. Discussion: ToM development in children with congenital blindness could be related to factors other than the loss of a sensory function and the lack of visual social and communicative experiences. Implications for practitioners: The specific ToM deficits in children with ocular-plus blindness may help in developing new research paradigms that consider delays in ToM in children with congenital blindness.

Previous studies have reported that congenitally blind children without any additional impairment reveal a developmental delay of at least 4 years in perspective taking based on testing first-order false-belief tasks. These authors interpret this delay as a sign of autism-like behavior. However, the delay may be caused by testing blind children with false-belief tasks that require visual experience. Therefore, the present study gave alternative false-belief tasks based on tactile or auditory experience to 45 congenitally blind 4-10-year-olds and 37 sighted 3-6-year-olds. Results showed criterion performance at 80 months (6; 8 years) in blind children compared with 61 months (5; 1 years) in sighted controls. It is concluded that this 19-month (1; 7 year) difference, which is comparable with delays in other developmental areas, is a developmental delay caused by the fact of congenital blindness rather than a sign of a psychopathological disorder of autism-like behavior. (Contains 4 tables and 7 figures.)