Prospective memory and what costs do not reveal about retrieval processes: A commentary on Smith, Hunt, McVay, and McConnell (2007).

On the basis of consistently finding significant overall costs to the ongoing task with a single salient target event, Smith, Hunt, McVay, and McConnell (2007) concluded that preparatory attentional processes are required for prospective remembering and that spontaneous retrieval does not occur. In this article, we argue that overall costs are not completely informative in terms of specifying the underlying processes mediating prospective memory retrieval, and we suggest more promising approaches for testing for the existence of these processes. We also argue that counterbalancing in a within-subjects design is one of several proper methods for assessing costs.