Age negatively impacted working memory performance. First, we collapsed data across post-stimulation memory blocks of the sham condition and found that older adults were markedly slower and less accurate at performing the task as compared with younger adults (Fig. 2a). No response biases were observed between age groups (t82 = 1.074, p = 0.286, dz = 0.234). Next, we examined the evolution and dynamics of behavior throughout the stimulation and post-stimulation periods by sorting the data from memory blocks into nine sequential 4-minute-long bins across the 75-minute recording period of the experiment (Fig. 2b, c). Both age groups showed gradual performance decline with increasing time on the task (older accuracy, F8,328 = 5.001, p = 0.009, partial η2 = 0.109; older RT, F8,328 = 4.859, p = 0.005, partial η2 = 0.106; younger accuracy, F8,328 = 3.059, p = 0.035, partial η2 = 0.069; younger RT, F8,328 = 6.431, p < 0.01, partial η2 = 0.136). However, no group x time interactions reached significance (accuracy, F8,656 = 1.418, p = 0.236, partial η2 = 0.017; RT, F8,656 = 2.055, p
