Experimental protocol of Experiments 1, 2, 3 and 4. Experiments 1, 3 and 4 had participants receive stimulation (15 minutes) before and during the word list-encoding portion of the CVLT. Participants completed spatial 2-back tasks during the CVLT delay periods, which followed the short delay free, recall (SDFR) and long delay free recall (LDFR). Experiment 2 had participants receive stimulation (15 minutes) during the 20 minute spatial 2-back before the LDFR. The forced-choice (FC) recognition portion of the CVLT was not included in Experiments 2, 3 and 4 because participants performed uniformly at ceiling in Experiment 1.