2020-07-12
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Charles Spearman didn’t like the idea of separating the mind into a number of independent learning abilities, memory, attention, and so on. What he wanted was to understand the operation of these faculties as a whole (1).
He carried out an experiment with a group of young children in a village school (1904). He obtained independent ratings of each child’s “cleverness in school” (from their teacher) and “sharpness and common sense out of school” (from two older children), and also measured their performance on three sensory tasks. He observed modest positive correlations (2)between all his measures.
In modern test theory, the reliability of a test is measured by the correlation between performance on the test on separate occasions, or performance on one half of the test versus the other. Spearman had no such information and instead assumed that the reliability of his three measures of intelligence (3) was the observed correlation between them, and similarly for the three sensory measures.
In fact, Spearman later acknowledged that these measures of reliability were inappropriate.
A much more important observation was one he made in data collected in another school (4), where he obtained somewhat more objective measures of academic performance, namely, each child’s rank order in class for each of four different subjects, as well as measures of musical ability as rated by their music teacher.
What was the meaning of this? Spearman’s “Two Factor” theory provided an answer. Each test measures its own specific factor, but also, to a greater or lesser extent, a general factor (5) that is common to all the tests in the battery. It is this general factor, which Spearman labeled g for general intelligence.
✓ reliability [rɪˌlaɪə'bɪlətɪ] -надёжность
✓ inappropriate [ˌɪnə'prəuprɪət] несоответствующий (требованиям)
✓ academicperformance – успеваемость, успехи в учёбе
✓ assume [ə's(j)uːm] допускать, предполагать
