2 Learning mode factors on vocabulary acquisition 2.1 Intentional and Incidental Vocabulary Learning Research on vocabulary acquisition in general, and in in-
cidental vocabulary acquisition in particular, has increased
largely over the past years. The concept of incidental vocab-
ulary acquisition first appeared in Nagy and Herman's re-
search on children's L1 vocabulary acquisition (Cited in
Zhu [3], 2004). Swanborn and De Glopper [4] (1999) define
incidental vocabulary learning as the incidental, as opposed
to intentional, derivation and learning of new word meanings
by subjects reading under reading circumstances that are fa-
miliar to them. The word incidental implies that the purpose
for reading does not specifically provoke learning or directing
attention to the meaning of unknown words. Wesche and Pa-
ribakht [5] (1999) believe that such learning is referred to
as incidental in that learners are focused on comprehending
meaning rather than on the explicit goal of learning new
words. Qian [6] (2002) defines incidental vocabulary acqui-
sition as learners' vocabulary learning based on the reading
purpose of text comprehension.
2.2 Direct and Indirect Vocabulary Learning Students learn vocabulary indirectly when they hear and
see words used in many different contexts, for example,
through conversations with others, through reading exten-
sively on their own, especially for children, they learn the
meanings of most words indirectly, through everyday experi-
ences with oral and written language.
Students learn vocabulary directly when they are explicitly
taught both individual words and word-learning strategies.
The scientific research on vocabulary instruction reveals that
most vocabulary is learned indirectly and some vocabulary
must be taught directly. Direct instruction helps students
learn difficult words and direct instruction of vocabulary rele-
vant to a given text leads to a better reading comprehension.
In Nation's view [12] (1990), direct vocabulary learning
and indirect vocabulary learning are two approaches to vocab-
ulary learning. He holds that, in direct vocabulary learning,
the learners do exercises and activities that focus their atten-
tion on vocabulary. Such exercises include word-building ex-
ercises, guessing words from context, learning words in lists,
and vocabulary games. In indirect vocabulary learning, the
learners' attention is focused on some other feature, usually
the message that is conveyed by a speaker or writer. And con-
siderable vocabulary learning can occur if the amount of un-
known vocabulary is low.