Lj. Cudmore et Sj. Segalowitz, Signal-to-noise ratio sensitivity in ERPs to stimulus and task complexity:Different effects for early and late components, BRAIN COGN, 43(1-3), 2000, pp. 130-134
Traditionally, early and late ERP components art: evaluated by the latency
and amplitude of their components. We investigated their signal-to-noise (S
/N) ratio: how well individual ERP trials correlate with their overall aver
aged ERP. High correlations indicate minimal noise or individual trial vari
ability while low correlations reflect greater trial variability. Continuou
s EEG activity was recorded from 57 university students during single- and
dual-task conditions in a within-subjects paradigm (easy and difficult tone
discrimination; with and without verbal working memory task). For early co
mponents, the addition of the second task increased the correlations betwee
n the individual trials and the averaged ERPs. For the late components, bot
h the addition of the second task and an increase in stimulus diffi- culty
decreased individual trial correlations. Results suggest that the S/N ratio
analysis is a useful method fur highlighting differences between early and
late components associated with stimulus processing manipulations. (C) 200
0 Academic Press.