ABSTRACT
This chapter addresses instances where double-task performance is inferior to single-task performance, insofar as performance is measured by reaction time. Double stimulation is usually defined as the presentation of two stimuli in rapid temporal succession. While a limited-capacity channel has a bottleneck, no such locus is specified in a variable allocation model. Indeed this class of model emphatically denies the very existence of a bottleneck. The response conflict model, originally proposed for single-stimulation data by Berlyne, and extended to psychological refractoriness by Reynolds and to all double-stimulation paradigms by Herman and Kantowitz, postulates response processing as the primary, but not necessarily the only, locus of double-stimulation effects. Buffer Model, which specifically locates a response selection bottleneck in short-term memory, has been proposed by Smith. Smith uses a two-stage model similar to that proposed by Atkinson and Juola to describe memory retrieval. In order for a response to be executed, the motor program residing in long-term memory needs to be accessed.
