Abstract
Previous research has found that adults rely on middle spatial frequencies for face recognition. The objectives of the present study were to follow the development of the mid-band bias in the typical population from early childhood and to compare this development in autism and Williams syndrome. The current paradigm was adapted from the adult literature to use across development and involved masking different spatial frequency bands in face images. Poorer performance when a particular band was masked would imply that this band was being used during face recognition. Thirty-six typically developing controls (TD), eighteen children with high-functioning autism (HFA) and fourteen children with Williams syndrome (WS) between 7- and 15-years-old learned to recognise two faces and then determined which face had been masked during presentation in a 2AFC task. Masks covered the face images at either 8 (LSF), 16 (MSF) or 32 (HSF) cycles per image. The use of each spatial frequency was plotted over developmental time for the three groups. In the TD group, 7-year-olds relied significantly more on HSF information than 15-year-olds, while the use of LSFs and MSFs were not significantly predicted by age. An adult-like bias towards the mid-band was evident by the age of 15. Interestingly, the HFA group followed an almost identical pattern. The WS group, however, demonstrated no change in the use of HSFs with age, but a decrease in the use of LSFs between 7- and 15- years-old. Both disorder groups displayed the adult-like mid-band bias found in typical development by the end of the age range studied. These data suggest that the mid-band bias emerges over an extended period of time during childhood. They also confirm the importance of comparing syndromes across a wide age range, demonstrating that the same adult outcome can be achieved through different developmental processes.
UK Medical Research Council, Grant G0701484 ID: 85031.