Vocabulary knowledge gained through extensive reading showed little decay on a three-month delayed posttest, with relative gains ranging from 21.05% (low-level) to 59.01% (high-level)¶

Claim · All claims
Evidence · 1 study · associational r1 · q3
Currency · newest study 2015 · checked against its sources 2026-10-17 (automated, 1 of 1 entry) · not reviewed by a person

Subclaims¶

Reading the evidence codes

q is the design tier, i the impact, n the sample, and the kind with its r the rigour judged within that kind: what each code means.

This claim: no standardized effect is recorded in observations/ for it yet, so no benchmark reading is possible.

q3 i? On the Term 1 three-month delayed posttest there was little decay in knowledge; relative gains ranged from 21.05% for the low-level group to 59.01% for the high-level group. → Stuart Webb and Anna C.-S. Chang 2015

Evidence¶

Stuart Webb and Anna C.-S. Chang 2015¶

Stuart Webb and Anna C.-S. Chang. (2015). HOW DOES PRIOR WORD KNOWLEDGE AFFECT VOCABULARY LEARNING PROGRESS IN AN EXTENSIVE READING PROGRAM? Studies in Second Language Acquisition, Volume 37, Issue 4, pp. 651-675. https://doi.org/10.1017/S0272263114000606

q3 · i? · associational · r1

Delayed posttest of Term 1 target words administered three months after the immediate posttest in the same 60-participant extensive reading study; the article reports "little decay in knowledge" with relative gains of 21.05% (low-level) to 59.01% (high-level).

"There was little decay in knowledge on the Term 1 three-month delayed posttest; relative gains ranged from 21.05% for the low-level group to 59.01% for the high-level group."

Discussion¶

Learner Variables¶

Reading and Language — outcome: instruction changes it
Vocabulary — outcome: instruction changes it

Vocabulary Knowledge Grows Incrementally With Repeated Encounters In Varied Contexts — the general claim this finding bears on, with the studies behind it
Extensive reading of graded readers produced substantial vocabulary learning gains for EFL learners across proficiency levels — related
Prior vocabulary knowledge moderates vocabulary learning gains in an extensive reading program, with high-level learners gaining more than intermediate and low-level learners — related
Incidental vocabulary exposure produces reliable learning, but learners pick up only a small share of the unknown words they meet — related
Gains from an intensive period of second-language study persist for weeks without rehearsal. — a broader claim this one bears on
L2 learners pick up vocabulary incidentally from meaning-focused input, with reading the most-studied mode and listening yielding similar proportions of words learned — a broader claim this one bears on
L2 proficiency positively predicts L2 incidental vocabulary acquisition through reading — related
Vocabulary learning gains in Term 2 of the extensive reading program were consistent with those from Term 1 — related
Vocabulary knowledge gained from eight encounters persisted over two weeks, with no significant immediate-to-delayed test differences — related

Page metadata

Field	Value
`type`	`claim`
`id`	`little-decay-three-month-delayed-posttest-extensive-reading`
`title`	`Vocabulary knowledge gained through extensive reading showed little decay on a three-month delayed posttest, with relative gains ranging from 21.05% (low-level) to 59.01% (high-level)`
`description`	`Vocabulary knowledge gained through extensive reading showed little decay on a three-month delayed posttest, with relative gains ranging from 21.05% (low-level) to 59.01% (high-level)`
`status`	`review`
`evidence_strength`	`moderate`
`newest_evidence`	`2015`
`source_checked`	`2026-10-17`
`generated`	by `process:wiki-ingest` on `2026-10-15`
`trust`	unverified — no one has confirmed this page's content
`sources`	1 — `stuart-webb-and-anna-c-s-chang-2015`

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