We used two experiments to investigate factors related to error in output monitoring. In the teaming phase, participants were presented with several action phrases from either an internal source (imagine) or an external source (enact). In the recall test phase, participants were asked to recollect as many action phrases as possible. In the output monitoring test phase, participants were asked to judge whether they had recalled each item during the recall test phase. The first and second experiments differed only in the type of recollection participants used (enact vs. imagine). We found that repeated enacting during the teaming phase increased output monitoring error under conditions where participants counted numerals as a secondary task during the recall test phase (experiments 1A, 2A) and under conditions where the output monitoring test phase was conducted seven days after the recall test phase (experiments IB, 2B). These results reveal that when participants were unable to use conscious recollection during the recall test phase, they did not rely on source memory but only relied on the strength of the memory.

Key words: output monitoring, source monitoring, enactment, imagery, attentional focus