1. Intelligence, IQ, and Crime
History of mental testing and IQ
The relationship between IQ and Crime
Issues of fake claims
Direct, or Indirect Effect
Criticisms of the Bell Curve

2. Alfred Binet French scientist who began in the field of “craniometry”
Began to doubt the validity of this method
Around 1900, he started “psychological” testing
(commissioned by government)
Devised “mental tasks” (counting coins, spatial reasoning

3. Binet’s Ideas
Scores are a “rough empirical guide” for identifying retarded children
They should not be used to rank normal children
Children identified as retarded should be helped
Low scores should not mark children as “innately incapable”

4. The Creation of “IQ”
Binet: eventually assigned a “mental age” to each task (normal child x years of age should complete)
Subtract the physical age from the mental age to see how big the gap was (identify those in need)
Later, others argued that the mental age should be divided by the physical age
“Intelligence Quotient” was born

5. The Americans!!!!
Binet’s methods adopted by scientists in U.S. They managed to break all of the “rules”
H.H. Goddard
coined the term “moron,” set at a mental age of 12 for an adult
avid in the eugenics movement
Lewis Terman
Created the “Stanford-Binet” IQ exam
Goal = “rational society” where people could be assigned jobs based on intelligence

6. IQ tests today No longer “mental age/physical age”
All correlate with the Stanford Binet or other early versions
Calibrated to produce a mean of 100
The “Flynn effect”
Still multiple tasks covering different cognitive areas

7. IQ and Crime
Early theorists found large differences between criminals and non-criminals
As testing improved, this difference shrunk
Sutherland (1940s): it will disappear
Currently: 8-10 point gap
Why this difference???

8. If relationship is real
The “Direct Effect Model”
(The Bell Curve)
Low IQ Crime
Indirect Effects
Low IQ school trouble Delinquency
labeling process
Interactive:
Low IQ is proxy for neuropsychological damage
(N.P. damage x Parenting) Delinquency

9. Criticisms of the Bell Curve
Only 3 variables in model (not enough control)
Could control for school performance, other factors
IQ explains only 3% of the variation in crime
The correlation is about .-06
Is this important enough to justify their policy implication??
Ranked with other “predictors,” IQ is near the bottom of the list