PMC3916771_01
Numerical Stroop task. Congruency effect (measured in terms of accuracy) for the two DD individuals. DD1 did not exhibit the canonical Congruency effect (Congruent > Neutral > Incongruent), while DD2 showed a clear Congruency pattern in the predicted direction. For DD1: Neutral > Congruent (p < 0.05); Congruent vs. Incongruent (p = 0.13); Incongruent vs. Neutral (p = 0.08). For DD2: Congruent > Incongruent (p < 0.05); Congruent vs. Neutral (p = 0.07); Incongruent vs. Neutral (p = 0.16). Data are mean +- standard error (SE) of the mean. *p < 0.05.
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F5
When presented with non-adjacent pairs, DD1 did not show any evidence of transitive inference, as she did not exhibit a congruency effect (Figure 5). In contrast, DD2 showed a congruency effect on the accuracy variable (Figure 5). Indeed, the behavioral outcome in DD2 is different from the one expected in neuro-typical adults (Figures 5, 6), suggesting that differential strategies might be adopted by the subject while solving the task.
Numerical distance by congruency effects. Effects measured in terms of RTs for each DD individual. DD1 did not exhibit the canonical Congruency effect (Incongruent > Neutral > Congruent), while DD2 showed a Congruency pattern related to the numerical distance between stimuli. For DD1 both Congruent as well as Incongruent trials were slower than Neutral trials (p < 0.001) and no effect of numerical distance was evident [F < 1]. In DD2, the canonical pattern typical of the Congruency effect (Incongruent > Congruent) was only present for small distances (e.g., 2-4) (p < 0.05); while the reverse pattern (Congruent > Incongruent) characterized DD2's performance with large numerical distances (e.g., 2-7) (p < 0.05). Main effects are shown in black (DD1's profile). Interaction is shown in shades of green (DD2's profile). Data are mean +- standard error (SE) of the mean. *p < 0.05; ***p < 0.001.
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F6
Moreover, DD2 showed a significant congruency effect also in terms of reaction times (Figure 6). Indeed, the behavioral outcome in DD2 is different from the one expected in neuro-typical adults (Figures 5, 6), suggesting that differential strategies might be adopted by the subject while solving the task.
Average location of subjective responses on the number line task plotted for each type of stimulation. Linear regression lines and equations are indicated for each type of stimulation (Red line:Right Anodal-Left Cathodal stimulation received by DD1; Blue line:Left Anodal-Right Cathodal stimulation received by DD2).
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F7
Namely, as reflected by her performance on the number line task, DD2 generated an accurate representation of the artificial digits; while DD1:who received Right Anodal:Left Cathodal tDCS:did not (Figure 7).