Measure your cognitive control with the classic Stroop test.
Reading the word RED printed in blue ink and naming the ink color forces your brain to suppress an automatic response (reading) in favor of a controlled one (color naming). Discovered by John Ridley Stroop in 1935, this interference effect is one of the most robust findings in experimental psychology and a standard probe of selective attention and inhibitory control.
The difference between your congruent (word matches color) and incongruent trial times — the interference cost — indexes executive control. Typical costs run 100-200 ms; smaller gaps indicate stronger inhibition. Performance worsens under sleep deprivation, stress and divided attention, which is why variants of this task appear in clinical and aviation screening.
Can focus be trained? Meditation practice and adequate sleep reliably improve inhibitory control; task-specific practice reduces Stroop interference but transfers only partially to daily distractibility.