Monitoring goal-irrelevant effects interferes with concurrent tasks

Our actions cause manifold environmental changes. Monitoring these action effects serves at least two vital functions: While the validation of currently relevant effects assesses goal-achievement, screening for currently irrelevant effects accumulates knowledge about potential action-effect relationships. However, monitoring the perceptual consequences of our actions presumably impairs performance in concurrent tasks. Here, we investigated how effect relevance modulates monitoring costs by manipulating instructions in three dual-task experiments. We found performance decreases not only after validation of goal-relevant action effects but to a smaller extent also after screening of goal-irrelevant action effects. These results suggest that effect monitoring is a rather fundamental limitation of dual tasking.