THE SS WERE REQUIRED TO KEEP TRACK MENTALLY OF THE NUMBER OF OCCURRENCES OF EACH OF 4 DIFFERENT SYMBOLS PRESENTED SEQUENTIALLY. IT WAS FOUND THAT A LIGHT INTRODUCED INTO THE SEQUENCE JUST PRIOR TO THE PRESENTATION OF EACH SUCCESSIVE SYMBOL TENDED TO ENHANCE PERFORMANCE. IT WAS SUGGESTED THAT THE LIGHT SERVED TO CUE SS TO COMPLETE REHEARSAL OF THE CURRENT STATE OF THE INFORMATION IN PREPARATION FOR THE NEXT STIMULUS IN THE SEQUENCE. (PsycINFO Database Record (c) 2006 APA, all rights reserved)