Intelligence as a Protective Factor against Offending: A Meta-Analytic Review of Prospective Longitudinal Studies

• In Event: Evidence-Based Crime Policy II

Abstract

We synthesize results from major prospective longitudinal studies that investigated whether intelligence may function as a protective factor against offending and violence. Results are based on systematic searches of the literature across 18 databases. Papers are included if results are based on longitudinal data and if the risk and protective factors are measured before the outcome of offending. Fifteen studies investigate the extent to which an above average intelligence may function as a protective factor. Meta-analytic results of studies on interactive protective factors suggest that a higher level of intelligence is a factor which can predict low levels of offending differentially within the high-risk (random effects model OR = 2.32; 95% CI: 1.49 – 3.63) and the low-risk (random effects model OR = 1.33; 95% CI: 0.88 – 2.01) groups. A high intelligence level is differentially protective against offending within different levels of risk. The high-risk and low-risk effect sizes were significantly different (mixed effects meta-regression: point estimate = 0.509; SE = 0.175; p = 0.004). Meta-analytic synthesis of studies that looked at risk-based protective factors (i.e., analyses based on high-risk individuals only) is also presented and results are consistent with initial hypotheses. Implications for policy and practice are highlighted.

Authors

• Maria M. Ttofi, Cambridge University

• David P. Farrington, Cambridge University

• Alex R. Piquero, University of Texas at Dallas

• Friedrich Loesel, Cambridge University / University of Erlangen-Nuremberg

• Matthew DeLisi, Iowa State University

• Joseph Murray, Federal University of Pelotas