ABSTRACT

A number of counfounding variables, such as word frequency, stimulus familiarity, age of acquisition of the object’s name, and visual complexity, have not always been properly controlled in studies on category-specific impairments (for the importance of these variables, see Forde & Humphreys, 1999; Funnell & Sheridan, 1992; Gaffan & Heywood; 1993; Stewart, Parkin, & Hunkin, 1992). Two important points should be taken into account when considering these confounding factors. The first point is that the exact mechanisms of these factors in category-specific disorders has been only partly clarified. The second point is to recognise that other confounding factors must be taken into account in category-specificity.