The effect of retrieval cues on post-retrieval monitoring in episodic memory: an electrophysiological study

The aim of the present experiment was to examine whether episodic retrieval and 'post-retrieval' monitoring are affected by the nature of the cue that guides a search of memory. We recorded event-related brain potentials (ERPs) from young healthy adult participants while they tried to recall studied words (e.g. 'MOTHER') with the aid of word-stem (e.g. 'MOT') and word-fragment (e.g. 'M-TH--') retrieval cues. Analyses of the behavioural data showed that while it was far more difficult to generate completions per se for the fragments, the levels of conscious, or 'explicit', recall obtained with each type of cue were statistically identical. ERP analyses focussed upon differences in neural activity evoked by each type of cue (termed 'old/new' ERP effects) during successful versus unsuccessful retrieval. The stem and fragment old/new ERP effects were remarkably similar in their time course and magnitude, and also in their scalp distribution, which changed over time as multiple neuronal populations, and hence multiple cognitive operations, became activated. These behavioural and ERP findings suggest that the cognitive operations reflected by old/new effects in cued recall tasks may be insensitive to changes in the retrieval strategy, or effort, that participants apply to monitor the episodic status of retrieved information. The findings are discussed in relation to previous ERP and functional imaging studies that have investigated task-specific features of retrieval and post-retrieval processing in episodic memory.