Velikonja, Diana2006-07-282006-07-2819971997http://hdl.handle.net/10012/124The effects of increasing arousal, through caffeine and task demand, on selective and sustained attention processes were examined. The auditory oddball task exemplified selective attention processes, while the contingent negative variation task exemplified sustained attention. Caffeine was administered to 27 adults in one of two test sessions. ERPs and EEG were recorded while participants performed 3 selective attention tasks of increasing difficulty; pitch oddball, a difficult duration oddball, and a dual task; and 2 sustained attention tasks: standard auditory CNV(1), and a more challenging CNV(2) task. In the easier selective attention task, caffeine decreased the latency at which auditory information was processed. As task difficulty increased during caffeine trials, there was a shift from decreased latency to increased: allocation of attention to the auditory tones. When task difficulty increased in the no-caffeine trials, there was an increase in the amplitudes of waveforms indexing stimulus discrimination and evaluation, as well as, an increase in the latency of stimulus evaluation. For sustained attention tasks, the amplitude of the E-wave significantly increased for CNV2. A reduction in the amplitude of this component was found with caffeine. EEG beta coherence showed a significant decrease in frontal-parietal regions between the pitch oddball and duration oddball tasks, and a significant increase in coherence between the duration oddball and dual task. For sustained attention tasks there was a significant decrease in frontal-parietal EEG alpha coherence between CNV1 and CNV2. These results support the notion of discrete attention systems located in anterior and posterior brain regions, respectively.application/pdf9133405 bytesapplication/pdfenCopyright: 1997, Velikonja, Diana. All rights reserved.Harvested from Collections CanadaDoctoral Thesis