Ensuring validity in Stroop test
• P: to ensure validity in our study on screen time and Stroop test performance, we took steps to address both internal and external threats, although some limitations remained
• E: internally, we reduced demand characteristics by avoiding a detailed explanation of the Stroop test beforehand, meaning participants were less likely to guess the aim and change their behaviour. We also minimised testing effects by allowing only one attempt at a task and ensuring participants left immediately after completing it, avoiding influence from others
• E: these controls helped ensure any differences in Stroop performance were more likely due to natural variations in screen time, rather than demand or learning effects. Externally, although our sample was narrow - 16-17 year old students in Abbeyfield Sixth form - the study had good ecological validity, as it was conducted in a school computing room..
