Rehabilitation of executive dysfunction following brain injury: “Content-free” cueing improves everyday prospective memory performance

Prospective memory (PM) is often claimed to rely upon executive as well as mnemonic resources. Here, we examined the contribution of executive functions towards PM by providing intermittent support for monitoring processes using "content-free" cues, which carried no direct information regarding the PM task itself. Twenty participants with non-progressive brain injury and PM difficulties received brief training in linking a cue phrase "STOP!" with pausing current activity and reviewing stored goals. The efficacy of this strategy was examined with a PM task requiring participants to make telephone calls to a voicemail service at four set times each day for 10 days. Task content was encoded using errorless learning to minimise retrospective memory-based failures. On five randomly selected days, eight text messages reading simply "STOP!" were sent to participants' mobile telephones, but crucially not within an hour of a target time. Striking improvements in performance were observed on cued days, thus demonstrating a within-subjects experimental modulation of PM performance using cues that carry no information other than by association with participants' stored memory of their intentions. In addition to the theoretical insights, the time course over which the effect was observed constitutes encouraging evidence that such strategies are useful in helping to remediate some negative consequences of executive dysfunction. It is proposed that this benefit results from enhanced efficiency of goal management via increased monitoring of current and future goals, and the steps necessary to achieve them, perhaps compensating for under-functioning fronto-parietal attention systems.