A meta-analysis on the influence of transcranial direct current stimulation (tDCS) on the processing of implicit associations (IATs)

Implicit biases are often costly to the self and others since implicit biases can impair cognitive functioning, social interactions, physical health, and psychological wellbeing. A variety of di erent interventions have therefore been used in an attempt to decrease implicit bias in participants including psychopharmacology, interpersonal and imaginary contact, cognitive and emotional training, and adopting alternative perspectives through virtual embodiment. Recently, brain stimulation techniques such as transcranial direct current stimulation (tDCS) have also been used with the goal of decreasing implicit bias in participants. But how e ective, if at all, is tDCS at decreasing implicit bias? The purpose of this research is to address this question by systematically reviewing all relevant studies that compared the in uence of tDCS versus sham stimulation on implicit bias as measured by a variety of implicit association tests (IATs). Using a random e ects model, this meta-analysis found a small e ect for tDCS versus sham on increasing RTs during IATs in males (k = 28, SMD = 0.252, p = 0.012) but a very small e ect for tDCS versus sham on decreasing RTs during IATs in females (k = 28, SMD = -0.140, p = 0.026). Further, this meta-analysis found no statistically signi cant e ect for tDCS versus sham on in uencing D values (bias scores) in males (k = 14, SMD = -0.176, p = 0.143) or in females (k = 14, SMD = 0.134, p = 0.081). Here I discuss the results of this research on tDCS and implicit associations, its practical value, along with limitations and prospects for future work.