Visual Perception and Cognition in Infancy

By Carl Granrud | Go to book overview
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Motion Nulling Techniques and Infant Color Vision

Davida Y. Teller Delwin T. Lindsey University of Washington

Since the 1970s, a variety of studies of infant chromatic discriminations and related topics have been carried out (reviewed by Brown, 1990; Teller & Bornstein, 1987). Most of the studies of chromatic discrimination have been motivated by classical trichromatic color theory, and the paradigms used have been guided by an interest in probing the functional maturity of the very earliest stage of chromatic processing in the visual system, that is, the photoreceptors.

The logic has been as follows: The initial encoding of wavelength information is made possible by the presence in the human retina of three different types of photoreceptors, the long-wavelength-sensitive (LWS), mid-wavelength- sensitive (MWS), and short-wavelength-sensitive (SWS) cones.1 Moreover, certain classes of adults, called dichromats, demonstrate highly specific losses of chromatic discrimination that stem from having only two, rather than all three, functional classes of cones. In adults, there are diagnostic tests for these color discrimination deficiencies. The most straightforward of these are called Rayleigh discriminations, which are possible only if the observer has both LWS cones

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1
The nomenclature used in color vision is confusing, and has undergone changes with time. Historically, cone types have sometimes been referred to by color names (e.g., blue, green, and red cones). However, most modern color theorists reserve color names to refer to color appearances or sensations, and not to elements of the neural substrate. Some modern theorists use the initials B, G, and R to refer to cone types, because they have mnemonic value in relation to the more familiar color names. Other color vision theorists prefer the terms S or SWS (short-wavelength- sensitive), M or MWS (mid-wavelength-sensitive), and L or LWS (long-wavelength-sensitive) cones, respectively.

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