Graduation Year


Document Type




Degree Granting Department


Major Professor

Raymond M. Hurley, Ph.D., Chair

Committee Member

Jennifer J. Lister, Ph.D.

Committee Member

Robert F. Zelski, Au.D.


normal hearing, P300, amplitude increment


The purpose of this study was to determine the effects of task difficulty on the amplitude and latency of the P300 by altering the intensity of the oddball stimulus. A P300 was obtained on 22 adult subjects ranging in age from 21 to 34 years of age (mean = 24 years) with normal hearing. The "frequent stimulus" was a 1000 Hz or 4000 Hz tone burst, gated with a rise and fall time of 10 msec and 20 msec plateau, presented at 75 dBn HL The "oddball stimulus" was a tone burst of the same frequency (1000 Hz or 4000 Hz)presented at 77, 79, or 81 dBn HL. A four-channel recording was made with linked reference electrodes and the following montages:Cz-A1+A2, Pz-A1+A2, and Fz-A1+A2. The fourth channel was used to monitor "eye blink" activity. The investigation tested the null hypothesis that changing the intensity of the oddball stimuli would not result in a significant change in either the amplitude or latency of the P300.

Analyses of Variance (ANOVA) indicate that P300 latency and amplitude did not differ significantly by run, stimulus frequency, intensity of the oddball, or montage. Thus the null hypothesis was supported.