Event-related potentials (ERPs) were recorded during
recognition tasks for line drawings (items) or for both
drawings and their spatial locations (sources). Recognized
drawings elicited more positive ERPs than new drawings.
Independent of accuracy in the spatial judgment, the old/new
effect in the source recognition task was larger over the
prefrontal scalp, and of longer temporal duration than
in the item recognition task, suggesting that the source
memory task engaged a qualitatively distinct memory process.
More posterior scalp sites were sensitive to the accuracy
of the source judgment, but this effect was delayed relative
to the difference between studied and unstudied drawings,
suggesting that source memory processes are completed after
item recognition. Similarities and differences between
spatial source memory and memory for conjunctions of other
stimulus attributes are discussed, together with the role
of prefrontal cortex in memory.