Modulating perceptual learning: Anodal transcranial direct current stimulation (tDCS) reduces the face inversion effect (FIE), while cathodal tDCS restores it to baseline.

We report three large experiments (n = 440 in total) investigating the effects of transcranial direct current stimulation (tDCS) at Fp3 on perceptual learning indexed by the face inversion effect (FIE). Experiments employed a double-blinded design, with participants randomly allocated to different tDCS groups. They then participated in an old/new recognition task involving both upright and inverted faces. Consistent with previous research, our findings indicate that anodal tDCS reduces the FIE compared to sham tDCS/control by impairing the recognition performance of upright faces. Crucially, our experiments introduced novel evidence suggesting that cathodal tDCS at Fp3 can reverse the effects of anodal tDCS, thereby restoring the FIE and performance for upright faces to typical levels. Across all three experiments, participants who received anodal tDCS followed by cathodal tDCS exhibited no reduction in the FIE nor impaired performance for upright faces. Moreover, Experiments 2 and 3 demonstrated that participants who only received cathodal tDCS showed no difference in the FIE compared to the sham/control group. This indicates that the effects of cathodal tDCS are specific to reversing the negative impact of anodal tDCS rather than affecting baseline performance. These results underscore that the detrimental effects of anodal tDCS on the FIE can be reversed through the application of cathodal tDCS. (PsycInfo Database Record (c) 2025 APA, all rights reserved).