Laurel Olson

Publication Date


Document Type


First Advisor

Ferre, Jeanane M.||Jackson, Pamela L.

Degree Name

M.A. (Master of Arts)

Legacy Department

Department of Communication Disorders


Auditory perception; Visual perception; Sensory stimulation


This study was designed to determine if the degree of perceived difficulty of a task has an effect on the latency of the P300 event-related potential (ERP). The latency of the ERP waveforms of ten female subjects, age 22-24 years (x̅ = 23 years), was evaluated for four tasks of reported increasing perceptual difficulty. Tonal stimuli in an odd-ball paradigm were verbally labelled, covertly counted, or compared for same/difference. In general, based on data analyses, three results were observed. First, ranking of the perceived difficulty was well correlated among subjects. Second, latency of P300 did not differ significantly as a function of task (p < .10). Previous research has demonstrated that the stimulus evaluation time is indexed by the latency of the P300. The results of this study suggested that it was not the perceived difficulty of the tasks that affected the stimulus evaluation time, but what the system actually was required to do. Closer examination of the tasks indicated that the system was required to make a fairly easy frequency discrimination, attach a label, then complete a motor act for each task. It would appear that the key to task difficulty was more related to the manipulation of the stimuli (as seen in previous studies) than manipulation of the response (as seen in this study). Finally, waveform morphology and latency were highly variable across subjects. However, within subjects, the waveform morphology and latency of the P300 response were very similar. This supported the conclusion that each task required the system to perform in the same manner, resulting in similar stimulus evaluation times and therefore similar P300 latencies.


Bibliography: pages [60]-64.


v, 70 pages




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