<p>In the foreign language classroom, the acquisition of vocabulary is basically left up to the individual student's rote memorization. Even if the audio-lingual approach (in which emphasis is placed on drills and practices) is employed, the memorization of vocabulary is still required mainly as part of the student's homework. Thus, it is the responsibility of the student to acquire as much vocabulary as he can, in whatever manner possible. For this reason, improving methods of vocabulary acquisition has been one of the important problems in foreign language learning. In the facilitation of vocabulary acquisition, there are several methods within which what is referred to as mnemonics; for example, the method of loci, the pegword method and the keyword method. The method of loci is one type of mnemonics whereby learners memorize words by applying them to places with which they are familiar: their houses, buildings within their hometown, and so on. A pegword is a word which rhymes with a number, such as "one" for "bun", "two" for "shoe", etc., and the learner tries to memorize the words in a list by means of association between the number in the list and the pegwords. A keyword is defined as a word or a phrase in the learner's native language which is similar in sound to one in the foreign language (target language). Vocabulary learning by the keyword method consists of two parts: one is association by sound between a keyword and a word of target language, and the other is association by image between them. Much previous research supports the effectiveness of the keyword method although further research is still necessary to improve it. Problems, such as whether the keyword method is effective with advanced learners as well as with beginners, whether or not keywords with some aids like vocalized short sentences or pictures are more effective than keywords only, or what parts of speech are most appropriate for the keyword method, still remain. The purpose of this study is to investigate those problems. Method The experiment was conducted in September, 1988. One hundred sixty-six male high school juniors served as subjects. Sixty-four English words were selected; 16 nouns high in concreteness, 16 nouns low in concreteness, 16 adjectives and 16 verbs. The nouns were chosen based on concreteness, imagery and meaningfulness values, and adjectives and verbs were selected based on frequency. The 64 words were randomized and arranged in a booklet, one word on each page. Four types of learning tasks were introduced: First, memorization of words without keywords; second, memorization of words with written keywords by the experimenters; third, memorization of words with keywords in addition to vocalized short sentences (which helped image link between the Japanese keyword and the English words); fourth, memorization of words with a keyword in addition to a picture (which helped the image link between them). All these tasks were paced, instructed and administered by tape. Subjects were given 15 seconds a word, and required to write the meaning of English words in Japanese as an immediate test. The same type of retention test was administered one week later. Results and Discussion The results of this experiment supported the following three points. First, the keyword method is significantly effective for advanced foreign language learners in terms of retention,(though the keyword method did not show any advantage in the immediate test). Second, a keyword was more effective when it was presented with a vocalized short sentence or a picture (which helped the meaningful association between a Japanese keyword and an English word) than when presented alone. From this result, some training to memorize words by use of use of keywords was necessary for learners to make this method facilitate vocabulary acquisition. The learner's</p><p>(View PDF for the rest of the abstract.)</p>