IQ and Delinquency

• Author: Ilhong Yun,Julak Lee
• DOI: 10.1177/1541204012463410
• Published date: 01 July 2013
• Date: 01 July 2013
• Subject Matter: Articles

Article
Youth Violence and Juvenile Justice
11(3) 196-211
IQ and Delinquency:
ª The Author(s) 2013
Reprints and permission:
The Differential Detection
sagepub.com/journalsPermissions.nav
DOI: 10.1177/1541204012463410
yvj.sagepub.com
Hypothesis Revisited
Ilhong Yun1 and Julak Lee2
Abstract
The purpose of this study is to examine the degree to which police arrest is influenced by an offenders’
level of verbal intelligence. Concomitantly, we examine whether the level of concentrated dis-
advantage of the neighborhood where the offender resides moderates the effect of verbal intelligence
on arrest. To accomplish this, we employed the National Longitudinal Study of Adolescent Health
(Add Health) to examine the extent to which persistent delinquent youths’ self-reported arrests are
significantly related to their verbal IQ scores. Furthermore, we also analyzed the interaction of verbal
IQ scores and neighborhood disadvantage net of an array of theoretically relevant control variables.
Keywords
verbal intelligence, differential detection, arrest, delinquency
A majority of adolescents engage in conduct that, if detected by the police, could result in an arrest.
Not all of them end up arrested by the police, however. This empirical reality clearly indicates that
law enforcement decisions do not flow only from consideration of legal factors, but there are also
certain nonlegal factors in operation. In a series of efforts to identify such nonlegal factors that might
influence police officers’ decision to adopt punitive sanctions, researchers have typically focused on
situational factors surrounding officer–offender encounters or officer’s psychological attributes
(Terrill & Reisig, 2003; Worden, 1989). To a lesser extent, police scholars have investigated
organizational factors and, more recently, neighborhood factors as potential determinants of police
behavior (Klinger, 1997; Warner & Coomer, 2003).
Recently, Beaver, DeLisi, Mears, and Stewart, (2009) garnered considerable attention by
demonstrating that a series of critical decisions of the actors in law enforcement and the court system
are affected by offenders’ level of self-control. Previous researchers had consistently noted that
disrespectful, belligerent, obdurate, and impulsive offenders were more likely to get arrested and
received harsher punishments (Black, 1976; Piliavin & Briar, 1964; Terrill & Reisig, 2003). Beaver
1 Department of Police Administration, Chosun University, Gwangju, South Korea
2 Department of Protection and Security Management, Kyonggi University, Gyonggi-do, South Korea
Corresponding Author:
Julak Lee, Department of Protection and Security Management, Kyonggi University, 154-42, Gwanggyosan-ro, Yongtong-gu
Suwon-si, Gyonggi-do, 443-760, South Korea.
Email: julaklee@hanmail.net

---

Yun and Lee
197
et al.’s (2009) study is meaningful by showing that low self-control is what potentially induces
offenders to behave disrespectfully, belligerently, and impulsively even at the immediate prospect
of arrest or imprisonment. Offenders with low self-control, according to this study, were not only
more likely to be stopped and arrested by the police but also more likely to be convicted than their
high self-control counterparts.
On a different note, a long line of research in clinical psychology and neuroscience indicates that
self-control, which is a part of a larger executive function housed in the prefrontal cortex of the
brain, is closely linked to verbal intelligence (Beaver, DeLisi, Vaughn, Wright, & Boutwell,
2008; Beaver & Wright, 2007; Luria, 1961; Moffitt, Caspi, Silva, & Stouthamer-Loeber, 1995).
Based on this literature, we hypothesize that offenders’ verbal intelligence also plays a statistically
meaningful role in shaping police officers’ decision to arrest. Thus, in the present study we examine
the extent to which police arrest is influenced by offenders’ level of verbal intelligence.
Concomitantly, we examine whether the type of neighborhood in which the offender resides
moderates the effect of an offender’s verbal intelligence on arrest.
Similar to Beaver et al. (2009), we use the National Longitudinal Study of Adolescent Health
(Add Health). The Add Health is singular in that it offers one of the largest nationally representative
longitudinal data sets of American adolescents (Udry, 1998), which includes adolescents’
self-reported delinquency, arrest experiences, and verbal intelligence test scores. To foreshadow our
findings, youthful delinquents with low verbal intelligence appear to be more likely to be arrested
than their counterparts of normal and higher verbal intelligence. More importantly, the effect of
verbal intelligence on arrest appears to be conditioned by neighborhood disadvantage.
Intelligence and Delinquency
Intelligence means dozens of different things to different people (Nisbett et al., 2012). Further, the
checkered history of biases and cruel criminal justice policies that were associated with the concept
of intelligence (Dugdale, 1877; Goddard, 1914) advise criminologists to remain vigilant for the mis-
use of it. Nevertheless, intelligence when measured through common IQ tests is a reasonably strong
correlate and predictor of a range of outcomes.1 For instance, the correlation between IQ scores and
school grades is about .5, meaning that about 25% of the variance of school performance is
explained by IQ scores (Neisser et al., 1996). Intelligence is also correlated with years of education
(r ¼ .55), job performance (r ¼ .54), and other various aspects of successes and failures in life
(Neisser et al., 1996).
IQ scores are also linked to delinquency, although the magnitude of the correlation is relatively
weak compared to other aforementioned outcomes. Nonetheless, it is as strong as the effect of social
class, and the IQ-delinquency relation holds up even after social class and race are controlled for
(Hirschi & Hindelang, 1977). The IQ differences found between delinquents and nondelinquents are
typically about eight points or half a standard deviation ([SD] Hirschi & Hindelang, 1977; Neisser
et al., 1996). Contrary to some researchers’ argument that the low IQ scores of delinquents merely
reflect the lack of test motivation typical of delinquent youths (Tarnopol, 1970), the IQ-delinquency
relation survives a statistical control of test motivation (Lynam, Moffitt, & Stouthamer-Loeber,
1993). Several studies also showed that the causal sequence flows from IQ to delinquency, and not
vice versa (Lynam et al., 1993; Moffitt et al., 1995).
There has been a heated scholarly debate on why such a relationship exists. Herrnstein and
Murray (1994), in their widely debated The Bell Curve, went so far as to suggest that IQ scores are
the primary cause of delinquency while excluding all other salient sociological variables, a claim
that was later repeatedly refuted as being pseudoscientific and politically oriented (Cullen,
Gendreau, Jarjoura, & Wright, 1997). One hypothesis that has garnered most empirical support thus
far is the school performance-mediation hypothesis. This hypothesis posits that intelligence and

---

198
Youth Violence and Juvenile Justice 11(3)
crime are related as a consequence of school performance, where low intelligence leads to poor
school performance, which, in turn, induces frustration and retards the growth of social bonds to
conventional institutions that may inhibit deviance (Hirschi & Hindelang, 1977; Ward & Tittle,
1994). Research that tested this hypothesis has consistently revealed evidence in support of this
position while disputing other competing hypotheses (McGloin & Pratt, 2003; McGloin, Pratt, &
Maahs, 2004; Moffitt & Silva, 1988).
IQ scores encompass varying dimensions, but it is worth noting that IQ deficits of delinquents are
concentrated in the verbal dimension. In contrast, youths’ abilities in visual, spatial, and motor
domains are generally less associated with delinquency. For instance, Moffitt et al. (1995),
employing the Dunedin Longitudinal Study, a prospective study of a cohort of 1,037 children born
in New Zealand, shows that verbal skills and verbal memory far outweighs other dimensions of
intelligence, such as visual–spatial, visual–moor integration, and mental flexibility in their predictive
ability of delinquency. Youths with low verbal IQ scores are also at risk for a range of other maladap-
tive developmental outcomes such as problems understanding and communicating emotions
accurately, self-regulation, and difficulties in social problem-solving skills and decision making
(Dionne, 2005; Moffitt et al., 1995). These findings indicate that deficits in verbal capacity are also
linked to deficits in the ‘‘executive function’’ of the brain that regulates planning, decision making,
and moderation of social behaviors of humans. Impulsive violent offenders are often found to have
deficient executive functions as well as low verbal IQ scores (Lynam et al., 1993; Moffitt et al., 1995).
Self-control, Verbal Skills, and the Differential Detection Hypothesis
The IQ-delinquency causation hypothesis has its fair share of competing hypotheses. One of the
competing hypotheses is what has been called the differential detection hypothesis. According to
this, the relationship between intelligence and delinquency is essentially spurious, and the one half
a SD IQ score differential between delinquents and nondelinquents merely reflects the fact that less
intelligent delinquents are more likely to be detected and arrested by the police, while their
intellectually advantaged...