INTRODUCTION
Adolescence, especially during the early years, is a period of important developmental changes and a time of stress and conflict. The physiological changes often precipitate special problems and doubts about self-concept, sexual identity, and relationships with others (Mussen et al., 1973). Research indicates that important changes in personality and cognition occur during adolescence, with early adolescence being the most crucial time. Kagan (1971) maintains that changes that occur during puberty "justify the positing of a psychological stage called early adolescence" (p. 998). Early adolescence encompasses the age range of 12 to 15 years (Gordon, 1971; Loevinger, 1976). At this time, society makes numerous demands on the individual and it is expected that these demands will be met within a very short period of time: achieving independence from the family; establishing satisfying give and take relationships with peers of both sexes; undertaking new tasks and social roles, and deciding on and preparing for a meaningful vocation (Kulas, 1986; Mussen et al., 1973).
Locus of control is defined as a generalized expectancy of internal or external control reinforcement (Rotter, 1966). The internally controlled individual believes that reinforcement is attributable to his/her own ability or efforts. The externally controlled individual believes that reinforcement is attributable to fate, chance, or some powerful external force.
The internal-external locus of control dimension has been one of the most widely researched personality variables in recent years. Numerous researchers have investigated the relationship between the perception of locus of control reinforcement and different aspects of personality, including perceived stress, motivation to attain goals, personal adjustment, hostility, and problem-solving strategies. However, relatively few studies have examined the relationship between age and locus of control beliefs, and surprisingly little is known about the nature of locus of control changes in adolescence. As Sherman (1984) noted, the vast majority of studies dealing with development of locus of control beliefs are cross-sectional in design. Baltes and Nesselroade (1972) point out that cross-sectional research confounds cultural and maturational components of change. According to them, the only way not to confuse these factors is to adopt longitudinal designs. Thus, a longitudinal design was employed in the present study.
The primary purpose of this study was to investigate the …