Matt, J., Leuthold, H., and Sommer, W. (1992) Differential effects of voluntary expectancies on reaction times and event-related potentials: Evidence for automatic and controlled expectancies. Journal of Experimental Psychology: Learning, Memory and Cognition, 18(4), pp. 810-822. (doi:10.1037/0278-73220.127.116.110)
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Expectancy has been used to explain the effects of stimulus sequences both on reaction times (RTs) and on the P300 component of the human event-related potential. However, there are conflicting views about the control obtainable over these underlying expectancies. The effects of voluntary expectancies for stimulus changes or repetitions in random tone series on RTs and the P300 were compared. Ss responded according to either stimulus identity (Exp 1) or stimulus sequence (Exp 2). In both experiments, RTs were strongly affected by event expectedness. P300 amplitude, on the other hand, was affected (as a trend) only in Exp 2. Results suggest that there are at least 2 types of "expectancy," one that is largely automatic and inflexible, reflected in P300 amplitude, and a second, controlled process that is reflected mainly in RT. The latter type of expectancy appears to affect processing stages beyond stimulus evaluation and classification.
|Glasgow Author(s) Enlighten ID:||Leuthold, Prof Hartmut|
|Authors:||Matt, J., Leuthold, H., and Sommer, W.|
|Subjects:||B Philosophy. Psychology. Religion > BF Psychology|
|College/School:||College of Science and Engineering > School of Psychology|
|Journal Name:||Journal of Experimental Psychology: Learning, Memory and Cognition|