The Effect of Explicit and Implicit Teaching Vocabulary on Iranian EFL Learners Vocabulary

This research aimed to find out and compare the effects of two types of teachinglearning vocabularies: explicit vs. implicit teaching-learning on building the EFL vocabulary of Iranian EFL students. The participants of the study were 100 intermediate females EFL students from four English classes. The instruments of this study included a PET test, a pre-test and a post-test. The researchers divided the sample into two groups which were given 15 sessions of treatment; the vocabulary items were taught explicitly to the Explicit Group (EG) by giving them the definitions of the words. However, to the second group, the Implicit Group (IG) the vocabulary items were taught implicitly by giving them example sentences in which the new words were used. After the treatments, a post-test was taken by the participants to examine the effects. The results showed that although both methods of teaching vocabulary were found to be effective, there was a significant difference between the post-test scores of the two groups; the EG which received explicit teaching-learning learnt much more vocabulary than the IG that received implicit teaching-learning of vocabulary. The findings of this study have several pedagogical implications in that they can make EFL teachers in Iran clearer about the more effective way for EFL classes to teach and learn vocabulary.


INTRODUCTION
A prominent feature which is shared amongst people and separates people from animals is the means of communication which can transfer large amounts of information and meaning.This process of exchanging information, expressing thoughts and feelings uses "vocabulary" which has a fundamental role in both developing people's knowledge and conveying meaning.As a person commences using a language, the need for vocabulary arises proving the importance of vocabulary.An urgent need for learning vocabulary precedes the learning of grammar in the acquisition of a first language.In addition, during the learning of a foreign language, the structure of rules is not necessarily perceived, but it is more than likely a wide range of vocabulary must be learned in order not to have a debilitating effect on communication.In the ESL context, vocabulary supports the four language skills (i.e.listening, speaking, reading, and writing), and thus ESL students often find that their lack of vocabulary is an obstacle to learning.Therefore, it follows that teaching-learning of ESL vocabulary often needs to be emphasized.Thornbury (2002) notes that with no knowledge about grammar the meaning is received in very small amounts, but with no knowledge of vocabulary nothing can be perceived (Subon, 2013).This statement shows that teaching-learning of ESL vocabulary must come first and any other methods must come in for criticism.Maiguashca (1993) states that till the middle of the 1980s, vocabulary was not mentioned as important.In the early 20 th century, John Dewey in 1910 stated that vocabulary is critically important because a word is an instrument for thinking about the meaning which it expresses, and since then, there has been an "ebb and flow of concern for (learning) vocabulary" (Manzo, Manzo, & Thomas, 2006, p. 612).At times, interest in teaching-learning vocabulary has been high and intense, and at other times low and neglected, alternating back and forth over time (Berne & Blachowicz, 2008).
There are many different learning styles, techniques and methods that can be used to help students keep new vocabulary in the mind and from among the diverse types of learning, the researchers chose to compare two types of vocabulary teaching-learning: explicit vocabulary teaching-learning versus implicit vocabulary teaching-learning.Moreover, this research was aimed to answer the following questions: 1) Does explicit teaching-learning of vocabulary affect the size of Iranian EFL secondary students' vocabulary more than implicit teaching-learning of vocabulary? 2) How does implicit teaching-learning of vocabulary affect the size of Iranian EFL secondary students' vocabulary?
2. LITERATURE REVIEW Richards and Renandya (2002) say vocabulary is a central component of language proficiency and is the basis for how well learners speak, listen, read, and write.They continued that with extensive vocabulary and strategies for acquiring new vocabulary, learners will achieve to their fullest potential and be encouraged to make use of language learning opportunities around them such as listening to the radio, listening to native speakers, using the language in different contexts, reading or watching television.Vocabulary can be defined as "the words we must know to communicate effectively: words in speaking (expressive vocabulary) and words in listening (receptive vocabulary)" (Neuman & Dwyer, 2009, p. 385).So, second language learning is deeply related to the size of vocabulary learnt (Nassaji, 2006).In the case of learning vocabulary, Harmon, Wood, and Kiser (2009) state that it is a continual process of encountering new words in meaningful and comprehensible contexts.Moreover, Smith (1998) has argued that vocabulary learning never stops and it is a natural and lifelong phenomenon.
We all know that certain fundamental techniques assist students to develop vocabulary such as flash cards, repetition, transcribing, writing, learning in context and revision.Hulstijn and Béjoint (1992) has demonstrated that target vocabulary items were retained significantly longer when their meanings were correctly inferred than when explained by their synonyms.Joe (1995) also argues that the retention of unfamiliar words was significantly facilitated when students engaged in a text-based task that demanded a higher level of generativity or engagement.Similarly, Hulstijn and Laufer (2001) have demonstrated that EFL students who participated in a composition task could retain target words better than those engaged in a reading comprehension or fill-in task, which suggests that students who are involved in higher levels of vocabulary production-processing will remember target words better than those who are not so involved.Paribakht and Wesche (1997) have stated that students remember unknown words better when provided with both pictorial and written annotations than when provided with only one kind or with no annotations.Hence, the researchers decided to investigate which of two types or techniques for teaching-learning vocabulary got the best results.
There are generally two types of vocabulary teaching-learning that can be used to teach students: explicit vocabulary teaching-learning versus implicit vocabulary teaching-learning.Ellis (1994) claims that implicit vocabulary teaching-learning methods involve indirect or incidental learning, whereas explicit methods involve direct or intentional teaching-learning.According to Berry (1994), a central concept in cognitive psychology as well as in second language acquisition research that has generated a host of fruitful work is the implicit/explicit distinction, which takes several different forms and has been applied to different referents.For instance, researchers are intrigued by the processes of implicit and explicit learning, by the nature of implicit and explicit knowledge, and by the effect of implicit and explicit teaching-learning strategies on language acquisition.In the realms of cognitive psychology and second language acquisition alike, the presence of awareness serves as a primary defining feature in terms of this implicit/explicit distinction.Schmitt (1998) has explained at great length the role of awareness in implicit and explicit teaching-learning, the definition of the former being "learning without awareness" whereas the latter is, "learning with awareness".The sheer weight that Schmitt (1998) has allocated to awareness (or attention/consciousness) is not accidental.Greenwood and Flanigan (2007, p. 249) argue that "90% of the words that a student learns over the course of a year are without direct instruction; these words are learned through incidental contact".Jenkins, Matlock, and Slocum (1989) assert that by explicit instruction, the instructor clearly outlines what the learning goals are for students, and offers clear, unambiguous explanations of the skills and information structures they are to be presented with in teaching.They continued that by implicit instruction, the instruction does not outline such goals or makes such explanation overtly, but rather simply in teaching.An overall review of literature will guide learners to investigate different ways of teaching-learning and the superiority of one to another.
McCarthy, O 'Dell, and Mark (1999) have proposed that speaking and writing English as a second language needs at least 1000-2000 vocabulary items.Marzban and Kamalian (2013, p. 85) have sought how to "transfer information from short term memory to long term memory, which has almost unlimited storage capacity".Explicit S. T. Yaghoubi & F. Seyyedi,The Effect of Explicit and Implicit Teaching Vocabulary on Iranian EFL Learners Vocabulary | 18 vocabulary learning refers to direct, rote ways of learning for retention, but when they are not practiced the vocabulary will not be "subsumed" and will be forgotten (Ausubel, 1964).Explicit vocabulary teaching-learning can involve word lists or handbooks and textbooks to help increase the size of vocabulary from elementary students to advance (Dimas, 2009).Berry (1994) has defined explicit learning as when people learn to employ the structure of the learning environment.But implicit teaching-learning does not use such deliberate strategies; implicit learning is so extensive in language work and the importance of this method is proposed due to the similarity to first language acquisition which is unconsciously received.Winter and Reber (1994) have asserted that the spirit of implicit learning is mirrored in the notion that people can absorb knowledge or information from the environment without being aware of the learning process.Similar viewpoints are presented by Schmitt and McCarthy (1997), who considers explicit learning the allocation of attention directly to the information to be learned.Explicit vocabulary learning refers to "conscious awareness and intention to learn" (Brown, 2000, p. 217) and implicit learning is the "acquisition of knowledge about the underlying structure of a complex stimulus from the environment by a process which takes place naturally, simply and without conscious operations" (Ellis, 1994, p. 1).
In contrast to implicit teaching-learning, explicit vocabulary teaching-learning uses kinds of teaching-learning that are employed consciously (Marzban & Kamalian, 2013).The performance of implicit learning in task-based language learning has caused this method to be one of the richest methods of learning (Marzban & Kamalian, 2013).Hulstijn (2001) has drawn a distinction between explicit vocabulary learning and implicit learning processes by which explicit vocabulary teaching-learning describes the sort of learning where students are officially informed and directly involved in this kind of learning, but in implicit teaching-learning participants are involved through the retention of information incidentally (Marzban & Kamalian, 2013).(Schmidt, 2000, p. 88), as cited in (Marzban & Kamalian, 2013), gives three definitions for incidental learning: 1. Learning without any intention to learn, 2. Learning of one stimulus aspect while paying attention to other stimuli, 3. Learning of formal features through a focus of attention on semantic features.Hunt and Beglar (2005) have proposed that the teaching-learning of words/vocabulary incidentally is performed better by advanced students than by novice learners whereas Brown (2007, p. 302) has mentioned that "children implicitly learn phonological, syntactic, semantic and pragmatic rules for language, but they do not have access to an explanation of those rules".In implicit teaching-learning the learner's ability to think about the meaning of words from the context is tangible (Hulstijn & Béjoint, 1992).Coady, Magoto, Hubbard, Graney, and Mokhtari (1993) investigated explicit instruction in high-frequency vocabulary and its effect on ESL reading comprehension.The subjects were 42 students of diverse proficiency levels enrolled in an intensive English program at the university level.Twenty-two subjects were assigned to the experimental group and the twenty others to the control group.The study was carried out in two phases.In phase one, all students completed a 36-item multiple-choice vocabulary test based on the basic vocabulary list and the Degrees of Reading test from the College Entrance Examination Board (CEEB) originally created for native speakers.
Both groups then received English instruction.In addition to the common treatment, the experimental group was given an additional computerized vocabulary learning program for one hour every week, over a period of eight weeks.Each session, this program presented the students with 20 words from the 600-2.000most frequent words used.
The students would access the computerized enhancements to the words unknown to them.Any selected or missed word was recycled into a personalized file for the student.At the end of the eight weeks, all participants had completed the same vocabulary and reading used for the pre-test.In the second phase of the experiment, the vocabulary was randomly selected from the computer program, and the reading comprehension measures as well as the reading texts were altered.The experiment was ended with a short closed-ended questionnaire as an evaluation of the computer program.The results showed that in phase one, the students in the experimental group experienced significantly greater gains in both reading comprehension and vocabulary knowledge (F(41,1) = 9.55, p<0.05).In phase two of the experiment, the students significantly increased their reading comprehension and vocabulary scores as shown by the t-tests (p<0.05).The majority of the participants indicated that they enjoyed using the program and felt that it helped them to learn vocabulary and improve their reading comprehension.The study clearly showed a link between reading comprehension and vocabulary and Coady et al. (1993) conclude that explicit teaching-learning of vocabulary will be more beneficial and will lead to longer retention as effective vocabulary needs to be automatically and easily retrievable from memory.Zimmerman (1997) has, however, stated three advantages of implicit/ incidental learning: 1.It is learning in context to get the use of words and their meaning.2. It is academically useful for both vocabulary acquisition and reading comprehension.3. It is more learner-centred to get the meanings in reading comprehension.
Compared to the past where explicit vocabulary teaching-learning used to excel, in the latest methods (CLT) the place of implicit learning is high.Marzban and Kamalian (2013) say that this is despite the fact that in this modern age some teachers still use explicit vocabulary teaching-learning in EFL classes (Zimmerman, 1997).Marzban and Kamalian (2013) conducted a research to find out the superior method between explicit and implicit learning and found that the explicit vocabulary teaching-learning method came first.In a study done by Mirzaii (2012), explicit vocabulary teaching-learning was also found to be more effective than implicit teaching-learning.Similarly, Karimi (2013), after 15 sessions of treatment with two groups, reported that explicit vocabulary teaching-learning improved Iranian EFL learners' vocabulary much more than implicit instruction.In this research, 36 preuniversity students were selected at random in order to study the effect of these two types of teaching-learning on the vocabulary of Iranian students.She divided them into two groups for explicit and implicit teaching-learning.In this study, the class following the explicit method was called the experimental group (EG) and the other group following the implicit learning method was called the control group (CG).Both groups took a pre-test to evaluate their writing ability at the beginning of the term and after the class room treatment, all the participants were given the same topic to write about in the post-test.The performance of the participants in the pre-test was almost equal, while the performance of the two groups in the post-test was significantly different.The result of the study indicated that the group receiving the explicit method of teaching-learning outperformed in using correct collocations in their English vocabulary.
The discrete nature of the University Entrance Exam in Iran requires teachers to manipulate the teaching-learning of explicit vocabulary.In this present study, the researchers proposed to investigate which method is superior in assisting participants to acquire more vocabulary in their minds to use when the need arises.This research focus on evaluating the effect of implicit versus explicit vocabulary teaching-learning on the size of the vocabulary learnt by the participants through using an experimental and a control group treated in two different ways of vocabulary practice so as to rate the effectiveness of each method on Iranian students writing due to the permanence of this process.

Participants
Out of eight classes of Intermediate Level of EFL Iranian students, whose ages ranged from 15 to 21, four classes were selected based on the results from a proficiency test.All of the participants were females from two branches of one of the Tabriz Institutes, named Shokouh.Based on the results of a Preliminary English Test (PET), they were all initially at about the same level of vocabulary proficiency.

Instruments and Materials
In order to examine the related effects of the treatment on the size of the participants' vocabulary, a pre-test and a post-test were given .The PET test was one of the instruments used in this research; it had 36 items, via: 20 multiple-choice reading questions, 10 close-tests and 6 paraphrased sentences to evaluate their homogeneity.Out of the 36 results, the researchers chose those who scored from 20 to 30.A pre-test and a post-test were done with both groups together before and after the 15 sessions of treatment.

Design
The method of this study was quasi-experimental; the students were selected randomly from eight classes.The independent variable of this study was the explicit or implicit teaching-learning of vocabulary and the dependent variable was the vocabulary knowledge of the EFL students.

Procedure
The sample was divided into two 10-student groups.Each group was given 15 treatment sessions, the EG was given explicit vocabulary teaching-learning and the IG was given implicit vocabulary teaching-learning.Classes were held 3 days a week and both classes were respectively taught from 4 p.m. to 6 p.m. and from 6 p.m. to 8 p.m. in the evening.In the first session, the researchers gave the pre-test and in the last session the post-test; the tests were given simultaneously to both groups.In the explicit vocabulary teaching-learning sessions the students were asked to check the meanings of the words from dictionaries or the teacher gave them the direct meaning (explicit vocabulary learning), but with the IG the teacher used body language, other meanings of the words and had discussion and interactions that made the students get the meanings through the context (implicit learning).In the 15 th session, the post-test was held with the same questions as in the pre-test.

Data Analysis
In the process of data analysis, the researchers used the SPSS software pack version for Windows.In order to compare the mean differences between the pre-test and the post-test scores within each group, the Paired Sample T-Test method of statistical analysis was used.Moreover, to compare the mean scores between the two groups, (EG and IG), one sample T-test was used.

RESULTS
As mentioned above, to analyse and compare the mean scores gained from the pre-tests and the post-tests within each group, the researchers used the Paired Sample T-Test method.The results from the test are shown in Table 1 below As the results show, significant differences were found within both groups since sig. is found to be less than the value of p which is 0.05.Based on these results, it seems that both methods of enhancing vocabulary knowledge were beneficial.One Sample T-Test was also used to compare the pre-test and the post-test scores between the two groups and the results are shown in Table 2 below.As the results show, no significant difference was found in the pre-test scores between the two groups.However, a significant difference was found between the posttest scores of the two groups.That is to say, the post-test scores of the EG who received S. T. Yaghoubi & F. Seyyedi,The Effect of Explicit and Implicit Teaching Vocabulary on Iranian EFL Learners Vocabulary | 22 explicit instructions during the sessions of treatment were significantly higher than the IG who received implicit instructions.In other words, explicit methods for teachinglearning vocabulary were more effective and beneficial than implicit methods.

DISCUSSION
The findings of this study indicated that although both explicit and implicit vocabulary teaching-learning methods improved the Iranian EFL learners' vocabulary positively, the explicit methods got better results than the implicit ones.The findings by Ellis (1994) offers a comprehensive review of implicit and explicit teaching-learning of vocabulary.His findings support our research results which conclude that both implicit and explicit processes are involved in vocabulary learning.Whereas some aspects of vocabulary learning are more amenable to conscious learning, some other aspects are more accommodating to explicit teaching-learning.Information concerning the surface forms such as the frequency, phonologic and orthographic regularity of vocabulary is acquired implicitly while semantic aspects are better acquired explicitly.The findings of this study is also in line with Mirzaii (2012) who has also reported that the explicit teaching-learning of vocabulary is more effective than implicit teaching-learning.Similarly, Marzban and Kamalian (2013) also found that the explicit teaching teachinglearning of vocabulary is more effective than teaching-learning vocabulary implicitly.Moreover, the findings of the current research support the results from the study conducted by Karimi (2013).
In contrast with our findings, Carter and Nunan (2002) indicate that in vocabulary acquisition studies, one key research direction is to explore the points at which implicit vocabulary teaching-learning is more efficient than explicit vocabulary teachinglearning.However, these results contrast with the findings from the study done by Nezakat-Alhossaini, Youhanaee, and Moinzadeh (2014) who found no significant difference between the results from explicit and implicit teaching-learning for the development of Iranian EFL learners' knowledge of vocabulary.

CONCLUSION
This research aimed to find out and compare the effects of two types of teaching: explicit and implicit teaching-learning for developing the EFL vocabulary of Iranian EFL secondary student learners.The finding of this study show that there was a significant difference between the post-test scores of the EG which received explicit teaching-learning and the IG that received implicit teaching-learning of vocabulary.The findings of this current study can have several pedagogical implications in that they can provide information for foreign language teachers on clearer ways for teaching-learning vocabulary items in EFL contexts such as Iran.EFL teachers should be aware of the importance of methods of teaching-learning vocabulary in classrooms and should try to use the best methods in their classes as much as possible to help learners learn more vocabulary.Teachers should also teach their students how to learn more vocabulary in English, to reflect on the processes of teaching-learning vocabulary and to focus on using the best explicit teaching-learning methods.

Table 1 .
. Paired differences (the mean difference is significant at the 0.05 level).

Table 2 .
Comparison of the pre-test and the post-test scores between the two groups.