"Encephalapp Stroop": Validity and reliability of a smartphone app to measure cognitive performance in physically active subjects

This study aimed to analyze the validity and reliability of a smartphone app (i.e., Encephalapp Stroop) to measure cognitive performance. Ten physically active individuals (mean age: 25.2 +/- 4.3 years) participated in three laboratory visits. In a randomized sequence, subjects completed cognitive assessments using the app and a computer separately. The response times from 100 measurements for congruent and incongruent stimuli were compared between the two devices (app and computer) using the intraclass correlation coefficient, Pearson product-moment correlation coefficient (r), Cronbach's alpha (alpha), and Bland-Altman plots. There was excellent agreement between the computerized Stroop and the app version for response times for congruent (ICC = 0.806, p < 0.001; Bland-Altman bias = 41.3 +/- 56.4 ms, p < 0.001) and incongruent stimuli (ICC = 0.755, p < 0.001; Bland-Altman bias = 76.4 +/- 75.1 ms, p < 0.001). In comparison to the computerized version, the app demonstrated a moderate correlation for response times of congruent (r = 0.678, p < 0.001) and incongruent (r = 0.623, p < 0.001) stimuli. The results of the present study indicate that the response times of congruent and incongruent stimuli can be easily, accurately, and reliably evaluated using a mobile app.