Introversion has the greatest chance of negatively affecting SLA. Students that are afraid of embarrassing themselves by speaking incorrectly or by not being able to speak at all may try to avoid opportunities that would otherwise aid their learning (Zhang, 2008).

Since 1960, personality has emerged as major field of specialization among doctoral candidates (Vance &ump; Macphail, 1964). Many investigations have been accomplished followed by literature on a variety of theories of personality. The importance on individual differences and distinctiveness of the individual are the most frequent features of the study of personality. There is a guarantee that each person’s profile is different from that of another person and thus, each person has unique personality (Allport &ump; Odbert, 1936). Nevertheless, the question is how do we determine personality? In general, the easiest approach to do this was through the observations of individual differences. Though, the validity and reliability of such observation can be questioned as it is not efficient and systematic adequately. On the other hand, the assessment of individual researcher may be subject to personal bias. Thus, in order to be accurate, personality theories often employ the systematic and scientific approach. The study can merely be called systematic and scientific when it concerned unbiased observations that are quantified so that systematic analyses can be performed (Allen, 1990). Dworkin and Kihlstrom (1978) underlined that the prediction of behavior will be improved by the use of personality tests. In line with this, many personality inventories with certain extent of reliability and validity have been developed to aid in the study of personality.

There are essentially two forms of personality tests that can be found in the literature. One of it is named projective test, allowing an extensive variety of freedom in making response, whereby the test items are more unstructured, vague or open-ended. Example of this is the Rorscharch Technique (1951). In the meantime another form of test is called the objective test. Objective tests are extremely structured paper and pencil questionnaires such as true/false or multiple choices, each of which can be scored with a key. Sidek personality Inventory is one case of an objective test. As objective tests are highly structured and scientific, they are higher in validity and reliability compared to projective tests.

Allport (1936) was the first one who considered the conception of traits as the origin of his theory of personality. Nevertheless, different psychologists have developed different list of essential traits and different measurement strategies to examine individual differences in a more consistent manner.

Hans Eysenck and Raymond Cattell were distinguished for their contribution in developing several measurement oriented process to trait theory. They underlined the significance of factor analysis to recognize fundamental traits. Hans Eysenck proposed three main types of super traits namely Extraversion/Introversion, Neuroticism, and Psychoticism through his personality inventories (Eysenck, 1990, 1967, &ump; 1952).

Personality study has a long history in the field of foreign language teaching and learning. Brown (1987) considers that personality will influence both the quality and quantity of foreign language learning. Rivers (1981) proposes that in a class group, instructors should identify personality factors which influence participation in discussion in the language.