This chapter focuses on individual differences as explanations for crime. It deals with intelligence, personality, and mental disorder, all of long-standing interest, both as “core” areas of applied psychology, and as sources of hypotheses concerning criminal behavior.

Intelligence

Introduction

The first scientist to construct an objective test of human intelligence was Francis Galton (a cousin of Charles Darwin). However, his tests, developed between 1860 and 1880, and largely to do with sensory functioning, failed to gain acceptance. Instead, the first successful and widely adopted test was devised by a Frenchman, Alfred Binet, whose work began in the 1890's and emphasized verbal skills such as reasoning. The Binet test crossed the Atlantic and, by the end of World War I, intelligence testing was in widespread use in the USA. The main attraction of intelligence tests is that, whatever “intelligence” is, a test such as the Wechsler–Bellevue is both highly reliable and a reasonably valid predictor of educational performance. There is evidence of a strong contribution of genetic inheritance to intelligence as measured by formal tests (Shields 1973), An association between criminal behavior and intelligence test scores would thus give some support to biological views of crime causation.