What does the brain do while playing scrabble?: ERPs associated with a short-long-term memory task

Event-related brain potentials (ERPs) were recorded while subjects performed the scrabble paradigm, a cued recall task that demands retrieving semantic memory information from long-term memory since subjects are not exposed to a previous study phase. The task combines short- and long-term memory processes and consists of forming words from a set of letters presented in random order. Short-term memory was manipulated by varying the number of letters (three, four and five) presented to the subject, while semantic memory was examined by comparing correct trials with no response trials. Behavioral results reveal that the subjects performed the task serially, as denoted by a linear reaction time increment as the number of random letters in the set increased. Short-term memory procedures were reflected by an amplitude increase of the N200 and by an amplitude decrease of the P300 increasing the number of letters. Successfully retrieving semantic information from long-term memory was indexed by a negative slow wave recorded at left frontal and left central sites, and by a positive slow wave predominant over right hemisphere sites. These findings provide evidence that semantic retrieval memory involves activity from both left and right hemispheres.