LATERALITY AND COGNITIVE INTERFERENCE IN STROOP LIKE TASKS AMONG RIGHT AND NON-RIGHT HANDERS

Abstract

This study investigates Stroop-like incongruency effect when emotional face, geometrical shape and color patches, are presented as paired stimuli in the form of image and word in split visual and parallel visual field to right-handed and non-right-handed individuals. The sample comprised 80 right-handers and 69 non-right handers males of 17-25 years of age. Self-report 10-items questionnaire were administered to determined handedness level. To access inconruency effect reaction time and accuracy were measured based on Stroop-like task with the help of JAVA based program in which pair of stimuli presented for 180 milliseconds on computer screen in the form of images (Emotional faces, Geometrical shapes and Color patches) and words (Emotional words, Geometrical shapes name and Color names) under three experiments over the 120 trials (60 split visual field and 60 parallel visual field) in congruent and incongruent conditions. Results reveal that in both visual field presentations i.e. split visual field and parallel visual field, non-right handers were faster in reaction and greater accuracy compared to right handers. So, the results demonstrated that, non-right handers had less incongruence effect in both types of stimuli i.e. word and images as compared to right handers in almost all the three experiments. The nature of stimuli was different in all three experiments but the incongruence effect was reported consistently as right handers had high incongruence effect during the recognition of different stimuli under both kinds of visual presentations. Further right handers were faster displaying high accuracy for word stimuli when stimuli presented in right visual field than the non-right handers in the all three Experiments. For image stimuli the right handers showed better performance when stimuli were presented in left visual field than the non-right handers in all three Experiments. These findings were strong under split visual field presentations than parallel visual field presentation. Surprisingly all these findings were quite consistent in the three experiments involving emotional, geometrical and color stimuli. The results of the current study deliver sufficient support to proposed two hypothesis, as well as it also supports different findings and theories that discussing an interaction of handedness and perception or cognitive functions. Further this study also gives different insight to understand the effect of handedness on Stroop like task as well as hemispheric dominance on perception of verbal and nonverbal materials. Apart from handedness, visual field is also a factor that effects visual perception that was also explained in this study.The findings that emerge from the study can be organized in a theoretical- conceptual framework. They are suggestive of the fact that the pattern of recognition of word and image stimuli varied across right and non-right handers. It also varied across the two visual fields, i.e. split visual field and parallel visual field. Nonright handers emerged as non-dominant or bilaterally dominant groups of people and these iii | P a g e people have lower level of incongruence generated interference as compared to the right handers. With the findings of this study it can also be stated that individual ways of perceiving stimuli are quite strong and consistently influence one’s perception. It appears that in Stroop like experiments the different visual field presentation methods can be helpful to decipher perceptual style and lateralization pattern.