Colour and Naming in Healthy and Aphasic People

Abstract

Abstract The purpose of this study was to create a paradigm suitable for people with aphasia and healthy subjects to evaluate the influence of colour on naming pictures of objects. We designed a completely new stimulus set based on images of 140 common real objects that were inspired by the Snodgrass and Vanderwart picture set (1980). We were especially interested whether there is a difference in performance between the aphasic patients and the group of healthy controls. Adding chromatic information to pictures of objects shows only a small effect in verification and categorisation tasks. However, when observers are required to name objects, colour speeds performance and enhances accuracy (Rossion & Pourtois, 2004). The present study contrasts two different claims as to why colour may benefit object naming. The first is that colour simply aids the segmentation of the object from its background (Wichmann et al., 2002). The second is that colour may help to elicit a wider range of associations with the object, thereby enhancing lexical access (Bisiach, 1966). To distinguish between these processes an equal number of pictures containing high and low colour diagnostic objects were presented against either fractal noise or uniform backgrounds in a naming task to aphasic subjects with anomia and to healthy controls. Performance for chromatic stimuli was compared with that for monochrome stimuli equated in luminance. Results show that colour facilitates naming significantly in both subject groups and there was no significant difference between objects with high or low colour diagnostic values. We also found that object segmentation and the lexical access seem to occur in parallel processes, rather than in an additive way