Date of Award
Doctor of Philosophy in Psychology
Quantitative EEG data were obtained for 22 male college students during a Resting condition and during performance of three continuous performance tests (CPT) that differed in the demands on linguistic processing. Previous EEG studies from our laboratory have indicated a relationship between left hemisphere beta power and performance of an auditory CPT that requires processing of phonetic stimuli. The participant listens to a series of letters and responds by pressing a button whenever the same letter is repeated twice in a row. This study was designed to test the hypothesis that left hemisphere EEG beta may reflect processing of language information. In this study our previous experimental protocol was repeated with the addition of a CPT that is completely non-verbal (tone task), as well as one that makes greater demands upon language processing (word task) then the letter task. Additionally, many EEG studies of cognitive function employ tasks that require a motor response. Gevins (1980) has cautioned researchers that many EEG effects that are interpretted as due to cognitive processing may be confounded by motor effects. In this study, hand use was manipulated i.e., participants performed each CPT with their left hand and with their right hand. Performance data were collected for percent correct responses (hits), reaction time for hits, and percent comission errors (false alarms). A repeated measures MANOVA was performed for performance which resulted in a significant condition effect. It was concluded that the three CPTs differed in task difficulty, which interacted with all the variables. A repeated measures ANOVA was performed on beta2, betal and alpha power scores at eight b i polar sites in four regions. Predictions for beta2 were not supported. Findings for the alpha waveband were in accordance with findings reported in the literature i.e., increases in brain activation are associated with decreases in EEG alpha power. Alpha was greater in the left hemisphere FT and T regions during the tone task than during the word task. These findings are consistent with the expectation that the tone task would require less processing demands of the language specialized left hemisphere than the word task would. A significant Hand used x Hemisphere x Region interaction was observed for alpha. A Hand used x Hemisphere follow up test was significant in the FT region. Compared to left hand use, when using the right hand the left hemisphere is activated and the right hemisphere is idle (deactivated). Compared to right hand use, when using the left hand the right hemisphere is activated and the left hemisphere is idle. This finding replicates a similar result found in this lab and by previous researchers (see text). Evidence is provided from this study that, at least for the alpha waveband, our CPT/EEG procedure is sensitive to variations in cognitive and motor processes. Possible applications are discussed.
Gold, Sherri M., "Quantitative EEG Effects Due to Task Related Processing of Lateralized Auditory Continuous Performance Tests, Separate from Attentional and Motor Components of the Tasks" (1994). Open Access Dissertations. Paper 1046.