Abstract
Categorical Perception (CP) is shown when stimuli that cross a category boundary are discriminated faster, more accurately or more easily than equivalently spaced stimuli from within a category. This thesis investigated the origin and nature of CP of color by asking three questions. First, is CP hardwired? Second, what is the effect of language on CP? Third, is CP really perceptual? These three questions were addressed in a series of experiments that took developmental and cross-cultural approaches. Category effects consistent with the CP model were shown in four-month old infants, toddlers and children across a range of boundaries, using a range of tasks. For the toddlers, there was no effect of colour term acquisition on the size of the category effect. Additionally, despite cross-cultural differences in naming, there were no cross-cultural differences in the size of the category effect in toddlers. There were cross-cultural differences in the category effect in children, although these differences could not easily be explained by differences in naming. The underlying mechanisms of the category effects were explored, certain mechanisms were ruled out, although the exact nature of the category effects in the infants, toddlers and children was unclear. Three conclusions were made. Firstly, it was concluded that the presence of categorical responding in infants may suggest that the category effect is hardwired, although it was also acknowledged that infant categories may be acquired. Secondly, it was concluded that language is not the origin of all category effects and that language does not modify the category effect in toddlers or in children. Finally, it was concluded that 'Categorical Perception' may actually be a range of effects, with a range of underlying mechanisms. Future research is suggested to investigate whether the category effects in infants are acquired, to investigate why effects of language on the category effect are found in adult but not toddler and child studies, and to investigate the exact nature of category effects found in infants, toddlers, children and adults.