Effect of Inaudible Binaural Beats Stimulation Timing and Task Performance Level on Visuospatial Working Memory

This study aimed to investigate the effect of inaudible-frequency binaural beats (BB), excluding the influence of audible sound, on visuospatial working memory performance (VSWMP). In particular, the effects were examined in relation to the stimulation timing of the stimulus and the task performance level of participants. Thirty adults in their 20 s (20 males, 25.7 ± 1.8 years; 10 females, 24.3 ± 1.6 years) participated in the experiment. A 10 Hz BB stimulus was generated by simultaneously presenting 18,000 Hz and 18,010 Hz tones to the left and right ears, respectively. The experiment employed a within-participant design consisting of a rest phase (5 min) and a task phase (5 min), with four BB stimulation conditions: Control (no BB), Exp1 (BB during both rest and task phases), Exp2 (BB during rest only), and Exp3 (BB during task only). VSWMP was assessed using corrected hit rate and reaction time in a 3-back task. Results indicated that all BB conditions (Exp1, Exp2, Exp3) significantly improved VSWMP compared to the Control condition, regardless of the stimulation timing. When participants were grouped based on task performance level into high- and low-performing groups (HPG, LPG), significant improvements in VSWMP were particularly evident in the LPG across all BB conditions compared to the Control. Notably, in Exp3, LPG participants demonstrated VSWMP comparable to that of the HPG. In conclusion, while BB stimulation enhances VSWMP regardless of its stimulation timing, its effectiveness may vary depending on the task performance level.