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Howard Andrew Knox was Assistant Surgeon at the immigration station at Ellis Island, New York, between April 1912 and May 1916. In response to public disquiet that the physicians at Ellis Island were failing to prevent mentally retarded people from entering the country, Knox and his colleagues assembled a collection of performance tests that could be administered to potential immigrants with little knowledge of the English language. They were subsequently used in clinical practice and in educational, psychological, and social research. Because of the early work done at Ellis Island, it is nowadays taken for granted that any adequate measure of intelligence must include both verbal and performance subtests.
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John T. E. Richardson (2003) studied this question.
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