Irrelevant tapping and the acoustic confusion effect: the effect of spatial complexity.

When items in a to-be-remembered list sound similar, recall performance is worse than when items are acoustically distinct, what is known as the acoustic confusion effect (ACE). When participants are asked to tap a syncopated rhythm during list presentation, the difference between the acoustically similar and dissimilar conditions is abolished; however, simple temporal and simple spatial tapping tasks have no effect. The objective of the present study is to examine whether spatial complexity is a property of the tapping task that interferes with the ACE. Participants were asked to tap a simple (Experiment 1) or a complex spatial pattern (Experiment 2) at a regular pace during a verbal serial recall task in which acoustic similarity was manipulated. The results showed that simple spatial tapping had no effect on the ACE, whereas complex spatial tapping significantly reduced the effect. Implications for three theories of memory are discussed.