Attention in character-classification tasks: Evidence for the automaticity of component stages.

Most theories of attention predict that engaging a subject in demanding concurrent activity will increase choice reaction time by an amount proportional to the attention demands of the choice task.The attention demands of mental operations within the choice task can be assessed by extending Sternberg's additivefactors method.Parameters associated with those processing stages that demand attention will interact with the amount of concurrent activity (i.e., will have greater effects with concurrent activity than without), but parameters associated with automatic processing stages will not (i.e., the joint effects will be additive).This analysis was applied to eight character-classification experiments.The classification task was either performed alone or in the retention interval of a short-term memory task which required ordered recall of 7 digits.According to the extended additive-factors method, the important effects are the interactions of classification-task parameters with memory load.The first two experiments reported validate the method with a memory-search task.Interactions were obtained between memory load and target-set size whose magnitude depended on the amount of practice with specific target sets.Inferences about attention demand and automaticity were shown to be consistent with those drawn from another criterion for automaticity, based on a different aspect of the data.The remaining six experiments examined four stages sufficient to perform a visual-search task (encoding, comparison, decision, and response selection).Memory load did not interact with parameters associated with encoding, decision and response-selection stages, and of three parameters associated with the comparison stage (target-set size, array size, and the presence or absence of a bar marker indicating the target's position), only target-set size interacted with memory load (Experiments 1 and 2).It was concluded that most of the processing involved in character classification does not require attention, and this was taken as evidence against models that identify attention with specific processingstructures.The results were interpreted as supporting the view that attention is a limited capacity to activate processing structures internally, and the role of attention in preparing, maintaining, and executing mental operations is discussed.