Repeated presentations raised free recall by about 15 points; spacing showed no effect after position control

We analyzed event files from OpenNeuro ds005411 RepFR1 (97 sessions, 47 SEEG patients, 23,772 studied words) to measure how repetition and spacing relate to free recall. Each list presented 3 words once, 3 words twice, and 6 words three times. Mean recall was 15.4%, 30.0%, and 44.5% after one, two, and three presentations. Each additional presentation raised recall by about 15 percentage points (P2−P1: +14.7, 95% CI 12.3 to 17.2; P3−P2: +14.5, 95% CI 12.3 to 16.7); both gains were positive in 45 of 47 subjects. Recall after two presentations did not differ significantly from the independent-encoding prediction, 1−(1−P1)^2 (+2.0 points, p=0.15), while recall after three presentations was 6.0 points above its prediction (95% CI 3.1 to 8.8, p=1.3e−4). In the raw comparison, long-lag two-presentation words had 8.8 points higher recall (95% CI 4.2 to 13.4, p=8e−4). This difference was absent after controlling for serial position (-4.7 points, 95% CI -11.3 to 1.4, p=0.17), consistent with the raw spacing difference reflecting recency. This event-only behavioral benchmark suggests that re-presentation can produce a larger recall gain than reported stimulation effects scaled in the original comparison. We did not analyze SEEG signals. The study did not examine word properties across repetition conditions, and the greater number of late-list presentations for three-presentation words means recency may contribute to their recall gain.

free recall · memory · word repetition · spacing · SEEG · brain-computer interface