Intelligence, IQ, and Crime
History of mental testing and IQ
The relationship between IQ and Crime
Issues of Spuriousness
Direct, or Indirect Effect
Criticisms of the Bell Curve
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 several “mental tasks” (counting coins, spatial reasoning)
Binet’s Admonishment
1.Scores are a practical device
– They do not buttress any theory of “intelligence”
2.Scores are a “rough empirical guide” for identifying retarded children
– They should not be used to rank normal children
3.Children identified as retarded should be helped
– Low scores should not mark children as “innately incapable”
The Creation of “IQ”
Binet: eventually assigned an “mental age” to each task (normal 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
The American “bastardization”
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
– 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
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
IQ and Crime
Early positivists (Goddard…) found large differences between criminals and non-criminals
– As testing improved, this difference shrunk
– Sutherland (1940s): it will dissapear
Currently: 8-10 point gap
Why this difference???
Possible Spuriousness
Race, Class, SES, Culture?
– Controlling for these effects, the relationship remains
Detection Hypothesis?
– Detected vs. Undetected offenders = no difference
Impulsivity?
– Ruled out through statistical control
If relationship is non-spurious
The “Direct Effect Model”
– (Hernnstien and Murray) Low IQ Crime
Indirect Effects
– Low IQ school trouble Delinquency
labeling process
Biological:
– Low IQ is proxy for neuropsychological damage
– (N.P. damage x Parenting) Delinquency
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