On language laterality in normal dextrals and sinistrals: results from the bilateral object naming latency task.
Rasmussen and Milner [N.Y.Acad. Sci. Vol. 299, pp. 355-379, 1977] published data on late-lesioned (after age 6) epileptic patients who had suffered left hemisphere lesions. They estimated that left hemisphere dominance occurred in 96% of dextrals and 70% of sinistrals. These figures have been regarded as valid estimates for normal dextrals and sinistrals. We administered the Bilateral Object Naming Latency Task, a verbal tachistoscopic task with very good psychometric properties, to 188 dextral and 72 sinistral normals. Results showed that 93.6% of the dextrals and 80.3% of the sinistrals were left hemisphere dominant. A consideration of results from a number of carefully conducted dichotic listening studies suggests, as do present results, that the 70% left-dominance estimate of Rasmussen and Milner for normal sinistrals may be too low by about 10%. It is suggested that 'bilateral dominance', present in 15% of the epileptic sinistrals of Rasmussen and Milner, may be much less common in normal sinistrals.
McKeever
W F
WF
Department of Psychology, University of Toledo, OH 43606, USA.
Seitz
K S
KS
Krutsch
A J
AJ
Van Eys
P L
PL
D001921:Brain / Q000502:physiology*; D004007:Dichotic Listening Tests; D004292:Dominance, Cerebral / Q000502:physiology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007802:Language; D008297:Male; D011930:Reaction Time; D014794:Visual Fields