Task-switch costs subsequent to cue-only trials

There is abundant evidence that there is a performance cost associated with switching between tasks. This "switch cost" has been postulated to be driven by task performance on the preceding trial, but recent research challenges any necessary role of previous task performance in driving the cost. Across three experiments, we investigated whether it is difficult to switch from a task that was prepared but never performed. We replicated the finding of a switch cost following cue-only trials (involving no task performance) whilst controlling for a potential cue-switching confound. This cost was larger than that following completed trials when preparation interval was short (300 ms), and it reduced significantly with a longer preparation interval (1000 ms) on the current trial. We also found that preparing only to attend to a particular visual dimension (colour or shape) was sufficient to drive a significant subsequent switch cost, which appeared to be residual in nature; we speculate that this cost may reflect the persistence of unfulfilled task intentions and/or a strategic slowing when consecutive intentions conflict.