Twenge, Zhang, & Im (2004)

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Twenge, J. M., Zhang, L., & Im, C. (2004). It's beyond my control: A cross-temporal meta-analysis of increasing externality in locus of control, 1960-2002. Personality and Social Psychology Review, 8, 308-319.

In this meta-analysis, the authors compare the mean scores on the Rotter (1966) Internal-External Locus of Control scale over time. Higher scores reflect a more external locus of control, suggesting that the respondent believes his or her outcomes are determined more by environmental forces than his or her own choices and abilities.

Data

Study 1 focused on college samples. The authors used data from dissertations and masters theses listed in Dissertation Abstracts International from 1950 to 2002 as well as Rotter's (1966) normative sample, "the college student data points cited in Table 3 of Rotter's article and the college student data points in Appendix VII of Lefcourt (1982)," (p. 312) and a sample of 91 undergrads at San Diego State University between 2002 and 2003. This sample yielded 97 independent studies with 18,310 college students.

Results

The correlation between year of study (minus 2, to correct for lag between data collection and publication) and LOC scores was r=.70, weighting study by sample size. To provide a more concrete interpretation of the magnitude of this effect, the authors estimate that "Using Rotter's (1966) percentile ratings, the average 2002 participant scored around the 80th percentile." The scatterplot suggests a fairly continuous increase in externality over time. The authors conclude that "young Americans increasingly feel outside forces control their lives."

Critique

While the steady rise of externality in locus of control is certainly deserving of alarm, the authors link that increase to several other social indicators in a way that is not consistent with the empirical data. The authors state that "many indicators of the state of society seriously deteriorated during the past 4 decades of the 20th century. For example, the divorce rate increased, the violent crime rate skyrocketed, and the suicide rate for young people quadrupled (U.S. Bureau of the Census, 2001)" (p. 310). The rate of divorce per 1,000 population in the United States did increase dramatically from 2.5 in 1965 to 4.8 in 1975, but it remained fairly constant from 1975 through 1985 and since 1985 it has shown a steady decrease to its 2001 level of 4.0. The suicide rate per 100,000 population increased from 7.6 in 1950 to 10.6 in 1960 and then 11.5 in 1970, but in 2000 it was at 10.4, lower than it was in 1960. If externality in locus of control were linked to these social indicators, it seems more likely that they would follow the same linearly increasing pattern. That they have leveled off and in fact decreased suggests that the connection is not as direct as the authors imply.