Ta. Mondor, INTERACTION BETWEEN HANDEDNESS AND THE ATTENTIONAL BIAS DURING TESTS OF DICHOTIC-LISTENING PERFORMANCE, Neuropsychology, development, and cognition. Section A, Journal of clinical and experimental neuropsychology, 16(3), 1994, pp. 377-385
Perceptual advantages are typically interpreted as direct expressions
of underlying hemispheric functional asymmetries. However, many other
confounding factors including the asymmetric distribution of attention
may also contribute to either the magnitude or direction of any of th
ese advantages. In a series of experiments, Mondor and Bryden (1991, 1
992a, 1992b) found that right-handed subjects bias their attention tow
ard the right ear when faced with a difficult dichotic listening task.
The present study was undertaken to determine whether the direction o
f the attentional bias is associated with handedness. The focus of aud
itory spatial attention was manipulated in a dichotic listening paradi
gm by presenting a pretrial tone cue to the ear from which the subject
was required to report. The time period between the onset of the cue
and the onset of the dichotic trial (Stimulus Onset Asynchrony - SOA)
was varied in order to control the time available to orient attention
to the cued ear. Whereas performance for the right ear improved substa
ntially with SOA, that for the left ear improved only marginally. In a
ddition, because of this differential effect of the cue on right ear a
nd left ear performance, the magnitude of the right ear advantage was
inflated at 450 ms SOA from that apparent at 150 ms and 750 ms SOA. Th
ese findings are interpreted as evidence that, in contrast to right-ha
nders, left-handers bias their attention toward the left ear. This rel
ation between handedness and the direction of the attentional bias is
shown to have important implications for the interpretation of percept
ual asymmetries.