Proactive and Reactive Response Inhibition across the Lifespan
(A) SSRT-Unprepared, which measures the speed of reactive control, increases with age. However, this age-related decline is more rapid in men than women. Proactive control is quantified as the difference between Unprepared and Prepared SSRT, i.e. the amount by which inhibition is improved through preparation (difference between red and blue line). (B) In proactive control we observe a strikingly different pattern. Relative to performance in Unprepared trials, women at all ages improve more with preparation than men. Although the lines have a negative slope, the Age coefficient itself is not different from zero. The y-axis represents the improvement in SSRT between Unprepared and Prepared as a percentage of SSRT-Unprepared, such that more negative values indicate greater benefit of preparation on the speed of inhibition. (C) Higher attained education in participants aged 25 or over is not only associated with better reactive control (reduction in SSRT-Unprepared), but also with better proactive control (larger difference between red and blue bar). (D) The distribution of BDI scores is shown in the grey histogram. No relationship with reactive or proactive control was apparent. All error bars indicate 95% CI. BDI = Beck Depression Inventory; SSRT = stop-signal reaction time; GCSE = general certificate of secondary education; A-level = general certificate of education advanced level.