Lexical decision and visual hemifield: an examination of the RT-accuracy relationship

Visual hemifield, stimulus duration and angle of eccentricity were manipulated using a lexical decision paradigm (discrimination of words from non-words). Lexical decision was measured by several dependent variables: reaction time, (RT); accuracy, d'; and beta. The results support the generalization of RVF superiority in a lexical decision task for parafoveal stimulation for three dependent variables, RT, accuracy and d'. No significant effect of any stimulus manipulation was found for beta. When RT is plotted as a function of accuracy, the data separate into two groups (one for words, one for non-words) each best described by a linear equation with negative slope. The implication of this analysis is discussed, and the hypothesis offered that the same basic process discriminates words from non-words in a lexical decision task, regardless of visual field, parafoveal angle of eccentricity or stimulus duration. Visual field is processed no differently from the other stimulus manipulations.