Hemispheric differences in case processing

Area of Science:

• Neuroscience
• Psycholinguistics
• Cognitive Psychology

Background:

• Brain hemispheres exhibit specialized functions in language processing.
• Grammatical case marking in Serbo-Croatian nouns influences cognitive processing.
• Previous research indicates a 'nominative superiority effect' in lexical decision tasks.

Purpose of the Study:

• To compare morphosyntactic capacities of normal brain hemispheres.
• To investigate hemispheric processing of Serbo-Croatian nouns presented centrally and laterally.
• To examine the influence of grammatical case on lexical decision performance.

Main Methods:

• Lexical decision tasks involving Serbo-Croatian nouns in various grammatical cases.
• Central and lateral visual field presentation of stimuli to assess hemispheric specialization.
• Analysis of reaction times and error rates for words and nonwords.

Main Results:

• Confirmed the nominative superiority effect: faster and more accurate processing of nominative case words.
• Replicated the nominative superiority effect for right visual field stimuli (left hemisphere).
• Observed reduced case sensitivity in the left visual field (right hemisphere), particularly for word reaction times and nonword errors.

Conclusions:

• Central stimuli are processed by the left hemisphere; lateral stimuli by the initially receiving hemisphere.
• The right hemisphere demonstrates a frequency-sensitive lexicon but reduced sensitivity to grammatical case.
• Differences in lexicon structure or absence of morphological/syntactic mechanisms may explain right-hemisphere limitations.