HD-tDCS over the left DLPFC increases cued recall and subjective question familiarity rather than other aspects of memory and metamemory

Lack of effects of online HD-tDCS over the left or right DLPFC in an associative memory and metamemory monitoring task

“…To determine the sample size, a power analysis was conducted via G*Power software utilizing parameters (i.e., effect size, power) from prior HD-tDCS work [29,31,75,121]. This analysis determined that 28 participants were needed to obtain a medium effect size, with an alpha of 0.05 and 80% power [122].…”

“…Then, participants gave an FOK rating, in which they indicated how likely they thought they were to recognize the answer to the question at a later time, on a 1 to 10 scale, with 1 representing feeling 0-10% sure in their ability to recognize the correct answer and 10 representing feeling 91-100% sure in their ability to recognize the correct answer, and the other numbers representing 10% increments of increasing certainty. This rating scale has commonly been used in FOK studies [29,31,75,121] and utilizes percentages as anchor points to give the participants a concrete interval between each Likert point. Finally, participants completed a 3 item (1 correct, 2 incorrect) forced choice recognition test for the proverb/name pair, in which they were shown the proverb and asked to select the previously paired name.…”

“…The difficulty with replicating tDCS results could be due to a variety of factors, such as inadequate sample sizes, insufficient current, improper electrode placement, task difficulty, and even individual differences in participants [27,55]. Sample size was based on prior work [28,29,75,121] and power analyses, so this should have been a minimal issue. Current and electrode placement was also based on prior work, so impacts should be minimized.…”