Effects of Graded Texts on EFL College Students' Incidental ...

immediately after reading, one week after reading, and one month after reading,
aiming to measure learners’ productive and receptive gain and word retention. The
results indicated that only two encounters with unfamiliar words during reading can
positively affect learners’ vocabulary growth. Yet, learners with six exposures did
significantly better on both immediate, delayed receptive and productive vocabulary
tests whereas two and four exposures resulted in a small difference. The findings
first suggested that long term effect on adult L2 vocabulary growth during reading can
be guaranteed under the condition that texts are sufficiently rich for building
vocabulary knowledge. Moreover, though two exposures during reading already
result in word knowledge gain, lexical growth is more likely to be speeded up if the
exposure is increased to six encounters.
The major reason leading to these disparate results with measuring encounters is
the incremental nature <strong>of</strong> word learning process. A single encounter with a word in
context could already result in some amount <strong>of</strong> learning, while 50 exposures will still
not enable learners to build the complete and complex word knowledge needed for
productive use. As Huckin and Coady (1999) stressed “word-learning outcomes can
range over continua <strong>of</strong> lexical knowledge and use competencies from partial
recognition knowledge to precise knowledge and productive use capability” (p. 185).
In other words, researchers’ concepts <strong>of</strong> successful acquisition were different, and
thus, vocabulary learning was measured in different ways.
The other possibility involved in measuring word encounter frequency could be
that different degree <strong>of</strong> exposure is needed by different learners (Zahar, et al., 2001).
Zahar, Cobb, and Spada (2001) investigated the issue by recruiting 144 ESL learners
coming from a variety <strong>of</strong> first language backgrounds at five pr<strong>of</strong>iciency levels ranging
from beginners to bilinguals. Each student’s performance on Nation’s (1990)
Vocabulary Levels Test involving matching words to brief definitions at five
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