Changes in Stroop Task Performance Across the Life Span.

BACKGROUND: The Stroop test assesses attention and cognition. The selective attention assessed by this test varies in bilingualism, education, gender and advancing age. Thus, this study aimed to examine age related changes in reaction time using the Stroop test. METHODS: A cross-sectional study was conducted at Kathmandu University School of Medical Sciences between March 2025 and November 2025. A total of 210 participants aged 18 - 80 years were recruited through convenience sampling. Participants were categorized into three age groups: Group 1 (18-30 years), Group 2 (31-60 years), and Group 3 (>60-80 years). Each group consist 70 participants, 35 males and females. Each participant was assessed individually and instructed to read the control, congruent, and incongruent Stroop cards. Reaction time was measured using a digital stopwatch for each task. RESULTS: Reaction time demonstrated a significant age related increase across all task conditions. In the control condition, the mean reaction time increased from 21.19 ± 6.80 seconds to 30.38 ± 10.76 seconds and further to 45.13 ± 12.69 seconds (p < 0.001). A comparable pattern was observed in the congruent condition, where mean reaction times rose from 20.41 ± 5.32 seconds to 28.34 ± 9.27 seconds and 41.27 ± 9.69 seconds (p < 0.001). The most pronounced differences were evident in the incongruent condition, with reaction times increasing markedly from 63.64 ± 30.72 seconds to 104.48 ± 34.25 seconds and 141.32 ± 47.97 seconds (p < 0.001). CONCLUSIONS: Reaction time is significantly influenced by age. Older participants demonstrated slower responses, indicating an age-related decline in executive function and cognitive processing speed.