Influence of interhemispheric differences on the Stroop and the Reverse Stroop effect  

Nikolić M., Juranić I.
First author's affiliation: University of Zadar, Zadar, Croatia

The Stroop effect is demonstration of interference in the reaction time of a task, where subjects have to ignore the word’s semantic meaning and react on the word’s color. Opposite effect is the reverse Stroop effect where subjects have to react on the word’s semantic meaning and ignore the word’s color where extension of reaction time is also obvious. Methods; One of the possible explanation are interhemispheric differences in elaboration of information - so the aim of this study was to explore effects of interhemispheric differences on the Stroop and the reverse Stroop task in groups of extreme left handed (N = 10) and extreme right handed (N = 10) subjects. The subjects were asked to solve two kinds of tasks, Stroop (naming color) and reverse Stroop (reading word), within different conditions (neutral, congruent and incongruent for the Stroop task and congruent and incongruent for the reverse Stroop task). In every situation they reacted with right and left hand. In right handed group both effects were identified while in left handed group only Stroop effect occurred. Subjects from both groups made more mistakes in incongruent conditions of both tasks, because of interference which is caused with difference in semantic meaning and ink color of the word. Interesting finding is that in right handed group Stroop effect is larger when subjects were reacting with right hand and reverse Stroop effect when reacting with left hand. This is the result of difference in interhemispheric elaboration of information where left hemisphere is dominant for verbal information and right hemisphere for color information. This has not been identified in left handed group because left handed individuals have more fibers in corpus callosum, which ensures better interhemispheric interaction and reduces interference.