The right visual field advantage and the optimal viewing position effect: On the relation between foveal and parafoveal word recognition.

Abstract

Recent developments on the optimal viewing position (OVP) effect suggest that it may be caused by the same factors that underlie the right visual field advantage in word recognition. This raises the question of the relationship between foveal and parafoveal word recognition. Three experiments are reported in which participants identified tachistoscopically presented words that were presented randomly in foveal and parafoveal vision. The results show that both the OVP effect and the right visual field advantage for word recognition are part of a larger extended OVP curve that has the shape of a Gaussian distribution with the mode shifted to the left of the center of the stimulus word. The shift of the distribution is a function of word length, but not of presentation duration; it is also slightly moderated by the information value of word beginning and word end. Tachistoscopic visual half field (VHF) studies are frequently used to assess the laterality of cognitive functions. They are based on the fact that stimuli presented in the left half of the visual field (LVF) are initially projected to the right cerebral hemisphere, and stimuli shown in the right half (RVF) are sent to the left cerebral hemisphere. This anatomical feature has been taken as support for the argument that LVF-RVF differences are an index of asymmetric functioning of the two cerebral hemispheres (for reviews see Bradshaw & Nettleton, 1983; Bryden, 1982; Hellige, 1993). Thus, the repeated finding that words are recognized more easily in the RVF than in the LVF is considered a consequence of left-hemisphere dominance for language processing. Further evidence for this position is obtained by finding that individuals with left hand preference show a reduced RVF superiority for word recognition relative to persons with right hand preference (Kim, 1994; but see Brysbaert, 1994c, for a more cautious account). The interpretation of LVF-RVF differences in word processing as an indication of laterality has not remained unchallenged, however. At least three alternative explanations of the RVF superiority have been proposed. The first considers the