Investigating the cost to ongoing tasks not associated with prospective memory task requirements

The purpose of the current study was to investigate the relationship between prospective memory (PM) and consciousness by examining cost to ongoing activities, with cost assumed to reflect a direction of conscious resources away from the ongoing task in service of the PM task. Ongoing task blocks in which the PM task was relevant or irrelevant were alternated to achieve three aims: determine if cost would persist in irrelevant blocks when relevant and irrelevant blocks were clearly demarcated and irrelevant stimuli were incompatible with the PM task; investigate if costs would be greatest at the start of irrelevant blocks; and determine whether costs would occur when the irrelevant block preceded any relevant blocks. Costs were found in irrelevant blocks and greater cost at the start of the irrelevant blocks suggest the cost may be due in part to participants making decisions about the engagement of conscious resources at transition points.