DIFFERENTIATION OF HOLISTIC PROCESSING IN THE TIME COURSE OF LETTER RECOGNITION

  • Thomas Lachmann
  • Cees van Leeuwen

Abstract

Pairs of letters, pseudo-letters, and geometrical shapes were presented in a sequential same–different task, in which the time between the first and second items was varied. The seconditem was either presented in isolation or surrounded by an irrelevant geometrical shape thatcould be congruent or incongruent to the target. Congruence effects were obtained for shapesand pseudo-letters, but not for letters if the interval between the first and second items wasshort. Absence of congruence effects was interpreted as categorical influence on early visualintegration processes; letters are processed less holistically than non-letter shapes. Thepresent result indicates that categorical influence of letters depends on the time course ofstimulus processing. As a highly automatized process, it is effective for stimuli appearing at arelatively fast rate, whereas, a slower rate of stimulus presentation eliminates task-irrelevantcategorical influences.
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