Individual and Joint Contributions of the Cerebral Hemispheres to Language Comprehension

Normal language comprehension requires contributions from and cooperation of many parts of the brain, ranging from sensory areas that receive the initial physical input, through frontal and temporal areas associated with oft-characterized language subprocesses, to brain areas involved in perspective-taking and social cognition; thus a network of brain areas, in both cerebral hemispheres, is recruited during everyday language and discourse processes. The three experiments presented here examine the idea that some typically-studied language processes are composed of distinct contributions from each hemisphere, but that other processes require input from both hemispheres in order to be successfully engaged. Using event-related brain potentials, these studies explore individual and joint contributions of the two hemispheres over time during the comprehension of normal, plausible sentences. In order to bias processing to one hemisphere, sentence-final words are presented in the contralateral half of the visual field. Hemispheric asymmetries and symmetries are examined across several cognitive processing mechanisms, including those at perceptual, semantic, and later processing stages. Results show that, consistent with prior work, normal semantic processing as indexed by the N400 seems to reflect a combination of the processing biases of the two hemispheres. Rather than being composed of independent hemispheric contributions, some later processing stages of comprehension, dubbed semantic revision, seem to require hemispheric cooperation. Finally, the experiments show that the processing biases are flexible, as different experimental contexts lead to recruitment of the hemispheric biases to differing degrees. Understanding how the hemispheres cooperate over time during language comprehension has broad implications, and is a much needed step in the cognitive neuroscience of language processing. The research presented here provides part of an initial foundation for a full understanding of how the two hemispheres coordinate resources during complex cognitive phenomena such as language comprehension.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Psychology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Wlotko, Edward Wesley

Contributors dc:contributor

• Kara Federmeier

• Language, Linguistics

Language dc:language

eng

Identifier

(MiAaPQ)AAI3395538

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/82197