Attentional and structural constraints on visual encoding

We examined the mechanisms that mediate the transfer of information from visual input to storage in memory. Observers performed two concurrent tasks, one of which required input into memory. We discovered that the processes involved in the transfer of information from sensory input into memory cause slowing in concurrent cognitive tasks (dual-task slowing). We used the dual-task slowing effect to demonstrate that memory encoding requires more time when more information is to be encoded and to show that dual-task slowing occurs long after the initial perceptual encoding of visual information (Exp. 1). These results suggest a late and central locus of interaction between the two tasks. Experiment 2 also used two concurrent tasks. However, we reversed the direction of interaction between them and produced a memory deficit from the execution of a concurrent task. Together the results suggest that the mechanisms that encode information into memory belong to a family of mechanisms that are involved in dual-task slowing phenomena and that have been studied under the rubric of the PRP effect (psychological refractory period). We were able to locate the most probable locus of the dual-task interactions to a process that appears necessary for memory encoding. We call this process short-term consolidation.