The professional and theoretical context
Nowadays, we do not consider testing to be at the centre of our clinical work. But the history of psychology input to the care of learning disabled people begins with the history of testing. In the mid-19th century, Seguin’s pioneering work on the ‘physiological education’ of idiot children laid the groundwork for later development of nonverbal tests (Anastasi and Urbina, 1997). In the 1870s, Galton was working in England on the study of individual differences (see Galton, 1883), and in 1890 James McKeen Cattell coined the term mental test for the set of cognitive and physiological tasks that he had devised (Anastasi and Urbina, 1997). Spearman was much inﬂuenced by Galton’s early work, including his eugenic ideas. He invented the statistical technique of factor analysis to analyse correlations among variables. In experimenting with school children he discovered signiﬁcant correlations between different intellectual abilities, and developed the idea that in addition to speciﬁc abilities there was a ‘general intelligence’, g. This could be assessed by measuring a number of different abilities and pooling the results (Tulsky et al, 2003).