Syntes: Kim & Webb (2022) — spacing has a medium-to-large effect on second-language learning

Källa: Kim, S. K. & Webb, S. (2022). The Effects of Spaced Practice on Second Language Learning: A Meta-Analysis. https://doi.org/10.1111/lang.12479

Verified content

• [abstract] 98 effect sizes from 48 experiments (N = 3,411) on spaced practice in L2 learning.
• [abstract] Spacing had a medium-to-large effect on second-language learning.
• [abstract] Shorter spacing matched longer spacing on immediate posttests but was less effective on delayed posttests; equal and expanding schedules were statistically equivalent.

• [abstract] Effect-size variability was tied to learning target, number of sessions, type of practice, activity type, feedback timing and retention interval.

• [full text] Spaced vs massed: immediate g = 0.58 (95% CI 0.16 to 1.00; k = 11); delayed g = 0.80 (0.44 to 1.17; k = 15; I² = 82%).

• [full text] Delayed spaced vs massed by target (Table 2): vocabulary 1.15 (0.81 to 1.49; k = 10), grammar 0.11 (−0.32 to 0.54; k = 5); Q = 13.78, p < .001.
• [full text] Longer vs shorter spacing: immediate −0.15 (ns; k = 17); delayed 0.40 (0.16 to 0.64; k = 32). Delayed by age: adults 0.54 (k = 24) vs grades 1–12 −0.04 (k = 8), p = .04; by sessions: within one session 0.76 (k = 11) vs between separate sessions 0.18 (−0.10 to 0.45; k = 21), p = .01; by target: grammar 0.56 (k = 8), vocabulary 0.34 (k = 22).
• [full text] Equal vs expanding spacing: no reliable difference (immediate 0.15, delayed −0.15).
• [full text] Publication bias apparent for delayed spaced-vs-massed effects; p-uniform judged it negligible; the authors cannot rule bias out.

Limits

• Read level: full text (PDF supplied by Jonatan 2026-11-04, private). Tables extracted with pdftotext; numbers checked against the running text.
• [assessment] Young learners = grades 1–12, few effects. Grammar subgroups rest on 5–8 comparisons with wide intervals.
• [assessment] Used 2026-11-05 to weaken C23 (vocabulary vs grammar; within- vs between-session gaps).

Why it is in the library

Core meta-analysis for a Language-learning candidate on spaced vs massed L2 practice (Phase B Near seed).

Added 2026-10-27 by the project (Phase B expansional push). [abstract] = published abstract; [full text] = full text; [assessment] = judgement; [secondary] = secondary summary pending paper check.