**Section 2**

**Colour Processing** 

70 Advances in Object Recognition Systems

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**4**

*Portugal* 

**The Contribution of**

*Universidade do Algarve, Faro,* 

**Color to Object Recognition** 

Inês Bramão, Luís Faísca, Karl Magnus Petersson and Alexandra Reis *Cognitive Neuroscience Research Group, Departamento de Psicologia, Faculdade de Ciências Humanas e Sociais, & Institute of Biotechnology & Bioengineering/CBME,* 

The cognitive processes involved in object recognition remain a mystery to the cognitive sciences. We know that the visual system recognizes objects via multiple features, including shape, color, texture, and motion characteristics. However, the way these features are combined to recognize objects is still an open question. The purpose of this contribution is to review the research about the specific role of color information in object recognition. Given that the human brain incorporates specialized mechanisms to handle color perception in the visual environment, it is a fair question to ask what functional role color might play in everyday vision. Humans possess trichromatic color vision that most likely developed for specialized uses. For instance, color vision could be used to detect ripe fruit against a background of foliage (Gegenfurtner, 2003; Surridge, Osorio, & Mundy, 2003). Traditionally, theories of object recognition suggest that objects are recognized based on shape information, largely ignoring the role of color information (Biederman, 1987; Marr & Nishihara, 1978). However, more recently, a large body of behavioral, functional neuroimaging, and neurophysiological evidence suggests that color information make an important contribution to object recognition (for a review, see Tanaka, Weiskopf, & Williams, 2001). In the first part of this chapter we discuss the relevance of research on color effects in object recognition, while reviewing the neural mechanisms that support color perception. In the second part of the chapter we present a review of the literature exploring the color effects on object recognition and we discuss some apparently contradictory results described in the scientific literature. We also present the main results of a meta-analysis in which the behavioral literature on the effect of color in object recognition has been explored and integrated (Bramão, Reis, Petersson, & Faísca, 2011). In the third section, we review some of our own behavioral and electrophysiological data that might explain some of the conflicting results found in the literature, and we discuss the level at which color information might contributes to object recognition. We argue that the color effects in object

recognition depend on the color diagnosticity status of the specific objects.

All mammals possess dichromatic or monochromatic color vision, but only primates have trichromatic color vision. What is the ecological advantage of having trichromatic color

**2. Color processing in the human brain** 

**1. Introduction** 
