The additive factor method in rat information processing

Sternberg introduced the additive factor method as a tool for discovering a nd studying in choice reaction time situations in human subjects. Underlyin g the method is the notion that if information processing consists of succe ssive stages, then different factors affecting different stages must have a dditive effects on reaction-time measurements. The additive factor method h as been extensively used in humans but few attempts have been made to exami ne whether or not additive reaction lime patterns were obtainable in rats. In the present work, the subjects (13 Long-Evans rats) had to press down a lever and to respond to a visual (right or left) stimulus by releasing the lever and introducing the head into a lateral (right or left) operandum. Th e present findings show an additive pattern of effects of signal luminance and foreperiod duration on the mean reaction time which suggests that we ha ve successfully manipulated two stages of rat information processing - the preprocessing stage and the motor adjustment stage, respectively. According ly, the present study sets the basis for the basis for investigating the ef fects of invasive manipulations (pharmacological and/or lesional) on inform ation processing stages. (C) 2000 Elsevier Science B.V. All rights reserved .