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Updated: Aug 13, 2026

Visualizing Visual Adaptation
Published on: April 24, 2017
Covert colour processing in colour agnosia
Tanja C W Nijboer1, Martine J E van Zandvoort, Edward H F de Haan
1Psychological Laboratory, Helmholtz Instituut, Universiteit Utrecht Heidelberglaan 2, NL-3584 CS Utrecht, The Netherlands. t.c.w.nijboer@fss.uu.nl
Abstract:
Patients with colour agnosia can perceive colours and are able to match coloured patches on hue, but are unable to identify or categorise colours. It is a rare condition and there is as yet no agreement on the clinical definition or a generally accepted explanation. In line with observations from object agnosia and prosopagnosia, we hypothesised that (some of) these patients might still be able to process colour information at an implicit level. In this study, we investigated this possibility of implicit access to colour semantics and colour names in a man (MAH) who suffers from developmental colour agnosia. We designed two experimental computer tasks: an associative colour priming task with a lexical decision response and a reversed Stroop task. The results of these experiments suggest that there is indeed automatic processing of colour, although MAH was unable to explicitly use colour information.
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