Temporal changes in visual and acoustic codes in a letter-matching task

The objective of the present experiment was to examine the nature of the coding process in a letter-matching task. Letter pairs that were either visually confusable or acoustically confusable or both visually and acoustically confusable were presented tachistoscopically with a variable interval between the first letter and the comparison letter. The dependent measure was RT for the “different” responses to the three types of confusable items which were each assessed at four interstimulus intervals ranging from 0 to 2 sec. The results indicate that a visual code appears to be emphasized for approximately 1 sec, after which an acoustic code seems to be dominant. There is also evidence which indicates that the acoustic code does not immediately replace the visual code and that both may coexist for a brief period of time.