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Behavioural Neurology
Volume 2015 (2015), Article ID 960725, 12 pages
http://dx.doi.org/10.1155/2015/960725
Research Article

On Colour, Category Effects, and Alzheimer’s Disease: A Critical Review of Studies and Further Longitudinal Evidence

1Departamento de Psicología Básica I, Facultad de Psicología, UNED, Calle Juan del Rosal, No. 10, 28040 Madrid, Spain
2Departamento de Psicología Básica II (Procesos Cognitivos), Facultad de Psicología, Universidad Complutense de Madrid, Campus de Somosaguas, Pozuelo de Alarcón, 28223 Madrid, Spain

Received 15 February 2015; Revised 17 April 2015; Accepted 28 April 2015

Academic Editor: Andrea Romigi

Copyright © 2015 F. Javier Moreno-Martínez and Inmaculada C. Rodríguez-Rojo. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The role of colour in object recognition is controversial; in this study, a critical review of previous studies, as well as a longitudinal study, was conducted. We examined whether colour benefits the ability of Alzheimer’s disease (AD) patients and normal controls (NC) when naming items differing in colour diagnosticity: living things (LT) versus nonliving things (NLT). Eleven AD patients were evaluated twice with a temporal interval of 3 years; 26 NC were tested once. The participants performed a naming task (colour and greyscale photographs); the impact of nuisance variables (NVs) and potential ceiling effects were also controlled. Our results showed that (i) colour slightly favoured processing of items with higher colour diagnosticity (i.e., LT) in both groups; (ii) AD patients used colour information similarly to NC, retaining this ability over time; (iii) NVs played a significant role as naming predictors in all the participants, relegating domain to a minor plane; and (iv) category effects (better processing of NLT) were present in both groups. Finally, although patients underwent semantic longitudinal impairment, this was independent of colour deterioration. This finding provides better support to the view that colour is effective at the visual rather than at the semantic level of object processing.