Contextual interference effects on the acquisition, retention, and transfer of a motor skill

72

University physical-education service-class students, USA (36 male, 36 female)

N=72 students assigned to blocked (low CI) or random (high CI) acquisition on pretest, to equate initial ability. 54 acquisition trials on 3 barrier-knockdown tasks; retention at 10 min or 10 days, tested under BOTH blocked and random sequences (counterbalanced, Latin square); then 2 transfer tasks, one equal and one greater in complexity. Lab apparatus task, single site, n=36/group, no preregistration.

The founding contextual-interference reversal. Blocked practice was ~22% FASTER than random during acquisition (1.32 vs 1.69 s) but 32% SLOWER at delayed retention (1.73 vs 1.31 s) and worse at transfer. The canonical acquisition-vs-learning dissociation: judging a practice schedule by in-session performance selects the schedule that harms durable learning. (Audit correction: the acquisition gap is 22% faster for blocked, not 28%.)

Groups equated on pretest ability by design, so pre-existing aptitude is controlled, but individual differences in schedule response are never analysed.

The reversal replicates reliably on lab tasks with young adults (meta SMD ~0.6-0.9) but attenuates to non-significance in applied sport and in under-18s. A mechanism demonstration, not a generalisable prescription.