Three Card Monte, Monty Hall, Modus Operandi and 'Offender Profiling': Some Lessons of Modern Cognitive Science for the Law of Evidence

Abstract

If modern cognitive psychology teaches us anything, it is that humans are vulnerable to some predictable kinds of processing errors. We appear to be subject to a variety of cognitive tunnels from which it is difficult to escape even when they lead to error. Many of those cognitive tunnels deal with probability judgments. This is well illustrated by the famous Monte Hall problem, and by the results of various studies by Daniel Kahneman, Amos Tverski and others. Some, most notably Gerd Gigerenzer, have responded that these results do not show a fundamental irrationality, but are merely the side effects of “fast and frugal” heuristics developed by evolutionary pressures to allow quick and generally accurate processing in informationally rich environments. However, modern social arrangements may make heuristics that were beneficial when they evolved generate seriously wrong decisions in the informational environment in which we now operate. For instance, credibility judgments concerning other humans that worked well in small bands of acquaintances may not work so well with strangers in the big city, as anyone falling prey to a Ponzi scheme could attest. As our information derives from less and less local environments, our hard wired heuristics become less and less secure guides. A simple mind experiment involving multiple roulette wheels spun simultaneously in two separate rooms, establishes that in any informationally rich environment, there are coincidences that appear to be rare and meaningful, but are neither. One form of supposed expertise sometimes offered in criminal proceedings, and more often used in criminal investigation, “linkage analysis,” presents just such dangers. This asserted expertise, and the larger area from which it is derived, “offender profiling,” are rife with claims for which little empirical evidence exists. The history and empirical record relating to “linkage analysis” and “offender profiling” is examined, and the dangers they present illustrated by reference to various actual cases, particularly the New Jersey case of State v. Fortin.

Keywords: Evidence, Criminal Law, Criminal Procedure, Forensic Science, Cognitive Psychology