Visual field differences in semantic comparative judgments with digits and Kanji stimulus materials.

Hemisphere specialization for two types of semantic comparative judgments were examined. In the first experiment a pair of Arabic numerals of different physical size were displayed and subjects were asked to judge if the physical size of the stimulus and the numerical magnitude were congruent or not by pressing the appropriate button. Reaction times were faster in the right visual field than in the left visual field. In the second experiment a pair of different physical sized Kanji representing concrete objects were displayed and subjects were required to judge if the physical size of the Kanji was congruent or not with the relative real life object size by pressing the appropriate button. Reaction times were faster in the left visual field. In the third experiment a pair of different physical sized Kanji representing numerical magnitude were displayed and subjects judged if the physical size of the Kanji and the numerical magnitude were congruent or not. Results showed a right visual field advantage and eliminated the possibility that Kanji complexity was the cause of the left visual field advantage in the second experiment. These results were interpreted as providing support for the proposal that there are two types of semantic comparative judgments, one relying on the verbal code and the other relying on the use of imagery, and suggesting that the former calls for stronger engagement of the left hemisphere while the latter calls for a stronger contribution from the right hemisphere.