Number-Letter Task

A task-switching variant from Rogers and Monsell's tradition in which strings mix a letter and a digit, and a cue tells you which one to classify on each trial.

Both objects are always visible, so switching purely reflects reconfiguring attention between classification rules rather than between separate displays.

Slower responses when the classification rule changes from the previous trial — the same switch-cost logic used in cued task-switching paradigms.

It shrinks with practice but rarely vanishes, which supports the idea that at least part of the cost reflects genuine reconfiguration.

The mixed block follows the classic alternating-runs design: positions rotate in a fixed order so the task changes predictably, while the interval between your response and the next pair is drawn randomly from 150 to 1200 ms. At short intervals there is little time to prepare, so the switch cost measured there mainly reflects the preparation-limited residual cost.