Global and local mechanisms of perception of “compound letters”

Abstract

This study describes an algorithm of temporal interaction of spatial mechanisms for global and local analysis in recognition of “compound letters” by second-grade students including some with speech disorders. A method of “compound letters” was used that models some properties of reading without line-by-line text scanning. Large “compound letters” are composed of small letters. Large “compound letters” are congruent if they are composed of the same letters; otherwise, they are incongruent. The test subject was asked to recognize either a large (global task) or a small (local task) letter in the “compound letter” and press the corresponding button. The number of correct/incorrect responses and the reaction time were registered. The responses of second-grade students with and without speech disorders were compared. The percentage of correct responses in recognition of large and small, congruent and incongruent letters was identical, but the response times were different for these groups of test subjects. The temporal properties of interaction of vision system channels that are responsible for local and global analysis during text recognition and speech production were assumed to be important.