Effects of Interhemispheric Communication on Two-Digit Arabic Number Processing

We investigated interhemispheric communication and hemispheric style differences (analytic vs. holistic) in two-digit Arabic number comparison by employing the divided visual field paradigm. Interhemispheric communication modulated two-digit number comparison in a very specific way. While no advantage of interhemispheric communication was found with unit-decade compatible trials (e.g., 52 and 67, the decade comparison and unit comparison of the two numbers lead to the same response; see Nuerk et al., 2001), a significant advantage of interhemispheric interactions emerged in the attentionally more demanding incompatible trials (e.g., 47 and 62, decade and unit comparisons do not lead to the same response, because 4 < 6 but 7 > 2), thereby enhancing the efficiency of selective attention (c.f., Banich, 1998). Additionally, some results indicated a more analytical processing style in the left hemisphere and a relatively more holistic processing style in the right hemisphere.