Dual hemispheric processing in a letter matching task

Abstract

It has been reported that performance on recognition, detection, and matching tasks is enhanced if stimuli are projected to both sides of the visual field rather than to one side alone (Dimond, 1972). The present study investigated the claim that this phenomenon is due to the distribution of the burden of perceptual processing between the hemispheres. Three experiments were carried out using a matching paradigm in which RT and response errors were recorded. In all experiments, subjects were required to match two letters that were displayed separately on either side of a central fixation point (bilateral presentation) or were displayed together on the same side of the visual field (unilateral presentation). It was found that although lateral interference between adjacent stimuli was significantly implicated in the phenomenon, a strong residual effect, which could be tentatively ascribed to hemispheric mechanisms, remained in relation to letter name matches. It is argued that a model based on parallel hemispheric decision processes provides a better account of the data than does one based upon the notion of distributed perceptual processing.Several studies (e.g., Dimond, 1970Dimond, , 1972Elithorn & Barnett, 1967) have shown that performance on a reaction time (RT) task may be facilitated by projecting component stimuli of the task to different, rather than same, sides of the visual field. Dimond (1970), for example, presented arrow shapes to the left, right, or both sides of the visual field. Subjects were instructed to respond with the hand indicated by the arrow. On some trials, two arrows were presented simultaneously, one pointing in each direction, and a double response was required. On these trials, the two arrows were presented in either the left or the right visual field, or were divided so that one arrow appeared on each side of the visual field. The results of this experiment were striking. When a double response was required, RT was some 95 msec shorter when the arrows were divided between the two sides of the visual field. Dimond attributed this finding to the distribution of the burden of perceptual processing between the cerebral hemispheres. He argued that the arrival of stimuli in separate hemispheres, via opposite sides of the visual field, permits simultaneous analysis and encoding to occur in the two perceptual systems, thus reducing the overall time ordinarily required for such operations. In commenting on this explanation, he noted that if each hemisphere shared stimulus information with the other immediately upon receiving it, one would not expect the projection of stimuli to same or separate visual fields to have any differential effect upon performance.This implies that when stimuli are projected to both sides of the visual field, the two hemispheres are able to

Stages of functional processing and the bihemispheric recognition of Japanese Kana script

“…Compared to the previous studies (e.g. Banich & Belger, 1990;Belger & Banich, 1992;Coney, 1985;Davis & Schmit, 1973;Dimond & Beaumont, 1972), applying Japanese phonograms as stimuli to Japanese subjects reduced the effects of a left-to-right scanning habit on the bilateral visual fields performance. Furthermore, in order to equate the perceptual processing load across the hemispheres, a pair of targets (Kana scripts) and two distractors (digits) were presented for all of the trials.…”

“…For example, in the BVF condition of the NI task used in the present study and the previous studies (e.g. Banich & Belger, 1990;Coney, 1985;Davis & Schmit, 1973;Ludwig & Jeeves, 1996;Yoshizaki & Tsuji, in preparation), each hemisphere would involve an equal number of functional steps; perceptual identification followed by name identification. As far as the author knows, few studies have examined the effects of functional steps on bihemispheric processing using tasks in which the number of functional steps taxed in one hemisphere differed from that in the other when projecting the divided information to each hemisphere.…”

“…One way to demonstrate that the bilateral visual fields advantage was due to bilateral hemispheric processing is to show that the effects of the bilateral visual fields advantage depend on a variety of tasks that are assumed to systematically operate the information processes (Banich & Belger, 1990;Belger & Banich, 1992;Coney, 1985;Davis & Schmit, 1973;Dimond & Beaumont, 1972;Hatta & Tuji, 1993;Hatta & Yoshizaki, 1996, 1997Jeeves & Lamb, 1988;Ludwig & Jeeves, 1996;Norman, Jeeves, Milne, & Ludwig, 1992;Yoshizaki & Tsuji, in preparation). Although a conclusive view has not yet been obtained, Banich (1995a) proposed the weighty model, where as tasks become more computationally complex, the benefits of interhemispheric integration are enhanced.…”

Lateral Asymmetry in Phonological Processing: Relating Behavioral Measures to Neuroimaged Structures

“…It is not even possible, at present, to speculate sensibly whether the two hemispheres operate cooperatively or independently in relation to this task (c.f. Coney, 1985). However, under most of the processing scenarios that might be envisaged, it is likely that faster responses would be produced by the operation of two hemispheres, compared with the circumstance generally obtaining in the male brain in which only one hemisphere performs phonological processing.…”

Effects of Learning Experience on Bihemispheric Processing

“…1990: Beiger & Banich. 1992: Comptt)n & Mintzer, 2001: Coney, 1985: Davis & Schmit, 1973: Dimond & Beaumont, 1972: Hatta et al. 2002: Koivisto.…”