Title

Time of Day, Repeated Testing, and Interblock Interval Effects on P300 Amplitude

Document Type

Article

Publication Date

4-1-1990

Department

Psychology

Abstract

Time of day, repeated testing, and interblock interval effects on P300 amplitude were investigated. Subjects (N=50) were tested using a standard oddball paradigm in either morning or afternoon sessions consisting of six test blocks per session. Amplitude of P300 was significantly higher in the morning than in the afternoon for all test blocks. In addition, amplitude of P300 habituated across test blocks from a mean of 9.59 μV on Block 1 to a mean of 4.98 μV on Block 6. Inserting a one-hour interval between Blocks 2 and 3 attenuated the rate of habituation. The results indicate that time of day, repeated testing, and interblock intervals affect P300 amplitude. Amplitude changes due to time of day may reflect circadian variations in cognitive resources indexed by the P300 component, while decrements due to repeated testing may reflect changes in allocation of resources across test sessions.

Publication Title

Physiology and Behavior

Volume

47

Issue

4

First Page

653

Last Page

658