Automatic influences as accessibility bias in memory and stroop tasks: Toward a formal model

Automatic processes can operate to increase the accessibility of a particular response. A series of experiments using the process dissociation procedure will be reported to show that the effects of such accessibility bias are independent of those of more algorithmic (consciously controlled) bases for responding. For example, habit originating from training in the experimental setting can produce an accessibility bias whose effects are independent of recollection. Habit serves to increase the probability of a particular response regardless of whether it opposes or acts in concert with the effects of recollection, the intended basis for responding. The process dissociation procedure combines results from opposition (interference) and in-concert (facilitation) conditions to separate the contributions of automatic and consciously controlled processes. Use of the procedure is based on the assumption that automatic and controlled processes are independent bases for responding. This independence assumption can be instantiated in a model similar to a recent "counter model" advanced by Ratcliff and McKoon (1997) to provide an account of process dissociations that is more detailed, but consistent with, our original model. We have developed a variant of the counter model that accounts for effects on both speed and accuracy in Stroop tasks.