Diagnostic Utility: Experimental Demonstrations and Replications of Powerful Question Effects in High‐Stakes Deception Detection

The concept of diagnostic utility was used to create questions that would differentially affect deception detection accuracy. Six deception detection studies show that subtle differences in questioning produced accuracy rates that were predictably, substantially, and reliably above and below chance. The first 3 detection studies demonstrate that diagnostically useful questioning can reliably achieve accuracy rates over 70% with student and experienced judges. The fourth and fifth experiments demonstrated negative diagnostic utility among federal investigators but not students. The final experiment crossed 3 sets of interview questions with experience. Strong question effects produced a swing in accuracy from 32 to 73%. A questioning by experience interaction was also obtained.     

Are absolute frequencies,relative frequencies,or both effective in reducing cognitive biases?

Biases in probabilistic reasoning are affected by alterations in the presentation of judgment tasks. In our experiments, students made likelihood judgments that an event was produced by various causes. These judgments were made in terms of probability, relative frequency or absolute frequency on a full or a pruned list of causes. When they had little personal experience of the event (causes of death), the pruning bias was smaller with relative frequencies than with absolute frequencies or probabilities. When they had more personal experience of the event (missing a lecture), the bias was less with both types of frequency than with probability but still lowest with relative frequency. We suggest that likelihood information is usually stored as relative frequencies when it has been obtained from public sources but that it is based on event counts when it is derived from personal experience. Copyright © 2000 John Wiley & Sons, Ltd.     

Understanding of the current police caution (England and Wales)

The Criminal Justice and Public Order Act 1994 (England and Wales) modified suspects' right to silence during police questioning and required a new police caution. The current 37-word caution was introduced after it was found that a proposed 60-word draft version was too complex. The results of the present study show that, although more succinct, the current caution is no easier to explain. Even under optimal conditions, when the participants could focus on each sentence in turn, only 1 in 10 of the general population (n=15), 6 in 10 of A-level students preparing for university (n=72) and 9 in 10 police officers (n=21) demonstrated their understanding by explaining all three sentences correctly. For all groups, the difficulties were more marked when the caution was presented in its entirety, as would happen in real life. The complexity of the caution has serious implications for suspects in police detention. © 1998 John Wiley & Sons, Ltd.     

How Prevalent is Contract Cheating and to What Extent are Students Repeat Offenders?

Contract cheating, or plagiarism via paid ghostwriting, is a significant academic ethical issue, especially as reliable methods for its prevention and detection in students’ assignments remain elusive. Contract cheating in academic assessment has been the subject of much recent debate and concern. Although some scandals have attracted substantial media attention, little is known about the likely prevalence of contract cheating by students for their university assignments. Although rates of contract cheating tend to be low, criminological theories suggest that people who employ ghostwriters for their assignments are likely to re-offend, and little is known about re-offence rates in this form of academic misconduct. We combined previously-collected datasets (N = 1378) and conducted additional, and previously-unreported, analyses on self-report measures of contract cheating prevalence. We found that few students (3.5%), on aggregate, ever engaged in contract cheating but this varied substantially among samples (from 0.3% to 7.9%). Of those who ever engaged in contract cheating, 62.5% did so more than once. The data also suggested that engagement in contract cheating is influenced by opportunity. These figures may help policy makers, and researchers who are creating contract cheating detection methods, to estimate base rates of contract cheating and the likelihood of re-offence.