Cerebral asymmetries and experimental parameters: real differences and imaginary variations?

The basic conditions and stimulus parameters of the paradigm usually used to study visual field-hemisphere differences are reviewed. An argument is presented that a majority of published reports using this paradigm are, in fact, the same basic experiment. The similarity of many parameters over experiments constitutes a set of effects whose influence on our interpretations are not determinable since these parameters are seldom varied. Examples of unsuspected effects on lateralization are drawn from three studies carried out by the author and his colleagues.