Commission errors with forced response lag.

It is often necessary to retrieve intentions once a certain cue occurs in the environment. However, such prospective memory (PM) tasks can also be erroneously recalled even though they are no longer relevant and may result in commission errors. According to the dual mechanism account, commission errors occur because the intention is spontaneously retrieved, and there is a subsequent failure to suppress the associated action, resulting in erroneous instant execution. In three experiments, we tested whether failed response suppression is a prerequisite for commission errors. We set up a response lag condition in which participants had to delay their response to ongoing task trials for 1 s (Experiment 1) or 2 s (Experiments 2 and 3) and a pause condition in which the delay occurred between ongoing task trials. In both conditions, participants learned about a PM task and were then told that the PM task was cancelled. In addition, a control group with response lag executed the PM task and was subsequently told the task was finished. Later, all participants encountered several irrelevant PM cues. If failed response suppression is a prerequisite for commission errors, commission error rates should be non-existent in the response lag conditions, because participants had designated time to suppress the PM action. However, commission errors occurred at an equal rate in all lag and pause conditions. Due to this contradiction to the dual mechanism account, we suggest that the process for commission error occurrence should be reconsidered. Because commission errors appear not to be caused by failed response suppression, we discuss the idea that erroneous intentions might be formed when encountering the former PM cue and persist over delays between formation and execution.