Palmeri et al. (2002)

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Introduction to WO WO has lexical synesthesia, which means that achromatic words and alphanumeric characters are seen in bright and consistent colors. The subject, WO has experienced this form of synesthesia since childhood and describes that he experiences a visual imagery synesthesia in which spoken words evoke consistent colors in “his mind’s eye” (Pamleri et al., 2000, p.4127). Despite his synesthesia, he has normal trichromatic color vision, good stereopsis and normal visual acuity.

Method and Results The authors tested WO’s synesthesia as elicited by both local and global forms. (i.e. a large number “5” made of small “2s”) Depending on what the subject was attending to, the local or global form of the stimulus, WO experienced whatever color was consistently associated with that stimulus (i.e. light green for the “5” and orange for the “2s”). WO also elicited synesthesia in response to stereopic displays resulting from binocularly defined stimuli. The structure-from-motion defined stimuli, which consisted of arrows facing in different directions, which formed the percept of a number. WO readily demonstrated synesthesia by identifying the color for the number displayed. Palmeri et al. (2000) also conducted a modified stroop interference task in which WO was asked to name colors either congruent or incongruent with the ink color, using latency as the independent variable. WO showed significantly slower reaction time when the written color was incongruent with his synesthesia. In another modified stroop task WO was asked to name the color of the word, which was either congruent or incongruent with the colors normally evoked by his synesthetic experience. The reaction times evoked to name words printed in grey (control condition) had similar durations to the words printed in the appropriate synesthetic color. The final task included a visual search efficiency test consisting of comparable visual stimuli (i.e. a “2” among numerous “5s” or a “6” among numerous “8s”). The results showed that WO’s error rates and reaction times were significantly lower and than that of controls and he commented that the target number was easily distinguishable compared to the other digits.

Discussion

Synesthesia is an automatic condition that results in multimodal perceptual experiences from a unimodal sensory stimulus. Palmeri et. al. (2000) reported, “it appears that the binding of color and form takes place during the process of form recognition itself, with synesthetic colors available before the explicit recognition of the digits (p. 4130). The authors conclude that lexical synesthesia binds color to form before the synesthete consciously recognizes the stimulus. Thus, it seems that synesthesia occurs during central visual processing, instead during higher order, semantic processing.

See also: Synesthesia