4302
Psychophysical evidence is given for the existence of two distinct systems in human vision : a fast , sign - invariant system concerned with extracting contours and a slower , sign - sensitive system concerned with assigning surface color .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: GENE 
Text: {0} 
Answer:
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