Lexical decision, visual hemifield and angle of orientation

Varying the orientation of word or nonword target stimuli from 0 degrees to 90 degrees in a lexical decision-visual hemifield task results in an increase in RT and a decrease in accuracy and d'. RVF superiority, as measured by d' was found at all orientations. RVF superiority,as measured by RT was only found for stimulation by words at orientations of 0 degrees and 15 degrees. There was a significant bias to respond 'word' (log beta) only for stimulation of the RVF at orientations of 0 degrees and 15 degrees. Under all other conditions, there was no significant response bias. A 'normal' (horizontal) presentation format seems to be necessary for the finding of a greater RVF bias to respond 'word' and for RVF superiority in speed of processing linguistic stimuli. However, a horizontal presentation format does not seem to be necessary for the RVF superiority in its capability to discriminate words from nonwords. (C) 1997 Elsevier Science Ltd.