Conditional automaticity: interference effects on the implicit memory retrieval process.

Many studies have indicated that executing a secondary task during encoding has little influence on implicit memory (priming effect). However, relatively few studies have discussed the effect of interference on implicit memory during retrieval. Our previous studies found asymmetry between implicit encoding and retrieval processes, with the priming effect disrupted by retrieval interference. Therefore, the present study investigated why and how the priming effect is affected by interference at retrieval. We adopted a dual-task paradigm, with a lexical decision task as the memory task and an odd-even decision task as the interference task. The effect of interference during retrieval was assessed by comparing the performance in the interference condition with that in the full-attention condition. In Experiment 1, we observed that the priming effect was absent in the synchronous retrieval interference condition. In Experiment 2, asynchronous interference was also found to block the priming effect. To verify the assumption that the priming effect is sensitive to attentional resource competition during retrieval, we used two different manipulations (an extended stimulus interval in the dual-task paradigm, Experiment 3, and an interference inhibition manipulation, Experiment 4) known to reduce attentional distraction. In these experiments, the priming effect was protected from interference effects. We suggest that implicit memory retrieval could be regarded as a conditional automatic process that depends on a configuration of the cognitive system by attention and task sets. If the limited resources are occupied by another task, the implicit retrieval process can be impacted.