TEMPORAL CHANGES IN VISUAL AND ACOUSTIC CODES IN A LETTER-MATCHING TASK

The nature of the coding process in a letter-matching task was examined. Letter pairs that were either visually confusable or acoustically confusable or both visually and acoustically confusable were presented to human subjects tachistoscopically with variable interval between the 1st letter and the comparison letter. The dependent measure was RT [reaction time] for the different responses to the 3 types of confusable items which were each assessed at 4 interstimulus intervals ranging from 0-2 s. A visual code appeared to be emphasized for approximately 1 s, after which an acoustic code seemed to be dominant. There was also evidence which indicated that the acoustic code did not immediately replace the visual code and that both may coexist for a brief period of time.