Fig. 4: Accuracy and speed dynamics for the combined datasets.
From: Native learning ability and not age determines the effects of brain stimulation
The data depicted combines the Modeling and the Validation datasets, so each group contains individuals from all age groups. a Accuracy dynamics of the combined datasets, showing a clear differential effect of atDCS, detrimental to optimal learners and beneficial to suboptimal learners. The benefit of stimulation is most pronounced in the least efficient individuals (i.e., the low tier of suboptimal learners). The verum groups are colored to code stimulation benefits (blue), detriments (red), or a lack of effect (gray). b Speed dynamics in all learner tiers, with patterns being similar between stimulation conditions. Please note that the consistent improvement in speed (paired with the maintenance of accuracy) suggests a consistent improvement in performance throughout training, which does not support the notion of a ceiling effect in the performance of the task. The dynamics (both for accuracy and speed) are computed as the ratio of the score of each training block to the score of the first training block, reflecting the performance change relative to the first block. In all plots, the markers represent the average accuracy (a) and speed (b) of each training block (i.e., 6 blocks per day), and the shaded regions reflect the 95% confidence interval of the fitted lines. The hollow markers correspond to groups receiving either no stimulation or placebo stimulation, while the full markers correspond to the groups receiving verum stimulation. The table depicts the number of individuals assigned to each learner tier, and each column corresponds to young, middle-aged, and older adults receiving verum (V), placebo (P), or no stimulation (NS).
