Persistent methodological problems with evoked potential augmenting-reducing.

Abstract

Evoked potential (EP) amplitudes are known to be influenced by changes in the intensity of a visual stimulus. These EP amplitude-intensity functions have been linked to a wide variety of personality characteristics and neuro- and psychopathological conditions. Those individuals whose EP amplitudes increase in response to increasing stimulus intensity have been termed Augmenters while those exhibiting no amplitude increases or actual amplitude decrements have been referred to as Reducers. Serious methodological problems have been found with many of the procedures of evoked potential augmenting-reducing. Recently, new explanations for the EP augmenting-reducing phenomenon have been offered and attempts to counter some of our criticisms of augmenting-reducing methodology. Their report is itself characterized by a variety of problems. These problems together with those generally prevalent in the augmenting-reducing literature are discussed.