Task-Switching Paradigm

The task-switching paradigm measures cognitive flexibility — the ability to redirect attention and reconfigure mental processes when task demands change. Participants make a different judgement about the same stimuli on each trial, guided by an explicit word cue that changes unpredictably.

This implementation uses the alternating-cue mixed-block design introduced by Meiran (1996) and formalised by Monsell (2003). On every trial a single digit (1–4 or 6–9, excluding 5) is shown alongside a task cue: ODD / EVEN? requires a parity judgement, and LESS / MORE? requires a magnitude judgement. Both tasks use the same two response keys (left arrow = first category, right arrow = second category). The cue changes randomly across trials, producing a mix of switch trials (task different from the previous) and repeat trials (same task as the previous).

The primary dependent measure is the switch cost: the RT and accuracy advantage of repeat trials over switch trials. Switch costs are consistently 50–200 ms in RT and 2–8% in accuracy across healthy adult samples, reflecting the time and mental effort needed to reconfigure task-relevant stimulus–response mappings (Monsell, 2003). A secondary measure, the congruency effect, captures interference between tasks: stimuli whose two-task responses would be the same key (congruent: e.g. digit 3 — odd and less than 5 both → left) are compared with those whose responses would differ (incongruent: e.g. digit 7 — odd → left, greater than 5 → right). A response-code congruency effect indicates bivalent stimulus processing even when only one task is required.

The fixation duration varies unpredictably between 300 and 900 ms (four balanced levels per condition per block) so that participants cannot time their preparation to the stimulus onset. All participant-facing text is exposed as translatable parameters.