[Effects of noise letters upon selective identification of letters]

Eighteen undergraduate students participated in two experiments which were designed to investigate the effects of noise letters upon selective identification of target letters. The reaction time of pressing buttons to the target letter was measured under various combinations of accompanying noise letters located 1 degree 48' apart from a target in visual angle, and added noise letters inserted between the target and accompanying noise letters. The results provided evidence in favor of the hypothesis which attributes the interfering effects of noise letters not to the processing level, but to the response level. Moreover, the results suggested that the noise letter adjacent to a target plays an important part in this interference, though the noise letters can be processed even in the position as much as 1 degree 48' apart from a target, and that it is especially important what relations the adjacent noise letter has with the response of the target.