The small amount of laboratoïy data available does not clearly support this assumption and data from field work has never been gathered. The present study was designed to assess the consequences of demonstrating varied levels of detection effectiveness to suspecÈs prior to an interrogation. A mock crime involving money, threat of shock, and a fierd gues tioning technique were incl-uded to create a more realistic interrogation situation. Pupil size, pupil change, heart rate, heart change, and. the galvanic skin response \¡¡ere used to assess detection. AlI subjects, half of whom had committed a mock crime, \^rere instructed to appear innocent throughout a questioning session conducted by an interrogator blind to their actuar guilt or innocence. rn addition, half of the subjects in each group had also read that they would receive a painful but not permanently damaging electric shock if found guilty of the crime. Prior to the interrogation subjects received a demonstration of the physiological detection measurest effectiveness. Demonstrated effectiveness was manipurated through a series of rigged tests in which a subject chose a number from a set of cards and attempted to conceal the number. The feedback led subjects in different groups to berieve they had been detected 0å, 33 r/32, 66 2/3e", or looe" of the time. The A few respecÈable valÍdity studies have been reporËed. Lyon (1936) found 40 cases in a random selection of l-00 which could be confirmed by outside critería and of those 40

The Guilty Knowledge polygraph test (GKT) and a variation of the test, the Guilty Actions Test (GAT), were compared in a laboratory setting. 84 men who committed or witnessed a mock crime answered "No", repeated items, or remained silent in response to items on the GKT or GAT. A monetary reward was promised for appearing innocent on the test. An interaction with scores based on skin resistance showed that innocent witnesses tested on the GKT scored more in the guilt direction than subjects in any other groups. Subjects required to say "no" were more reactive to key items than subjects in the item repetition or silence groups. Thoracic respiration scores showed a difference between guilty and innocent subjects.

The effects of awareness of crime-relevant information on the detection of deception with the Guilty Knowledge Test were examined. Student subjects were assigned to 1 of 3 groups: a guilty group, members of which committed a mock crime; an innocent group aware of details about the crime; or an innocent group unaware of such information. After following instructions, subjects were tested on the polygraph with a 10-item Guilty Knowledge Test and were offered $20.00 for an innocent test outcome. Skin resistance response scores of guilty subjects lying about crime-relevant information were higher than the scores of innocent informed subjects, whose scores in turn were higher than those of innocent unaware subjects. This replicated findings of an earlier study in which similar procedures were used and supported the view that subjects aware of crime-relevant information can appear less deceptive than subjects lying about crime-relevant information.

Psychophysiological detection of deception examinations were conducted on 40 subjects. Of these, 32 were “guilty” of a mock crime and 8 were innocent. Sixteen guilty subjects committed the crime while intoxicated and the remaining 16 committed the crime sober. These two groups of guilty subjects were subdivided such that half of each group was examined with the polygraph while intoxicated and the other half was examined while sober. Two questioning techniques were used in the examination, a Control Question Test and the Guilty Knowledge Test. Measures of skin resistance, heart rate and respiration were recorded. The principal findings were that alcohol intoxication during the crime reduced detectability with detection scores derived from the measurement of skin resistance responses on the Control Question Test and on the Guilty Knowledge Test. The analyses of guilt/innocent classifications, based on the detection scores, showed these classifications to be affected by alcohol intoxication.

A simulation was conducted to assess the effect of technical variance on the statistical power of web experiments measuring response times. The results of the simulation showed that technical variance reduced the statistical power and the accuracy of the effect size estimate by a negligible magnitude. This finding therefore suggests that researchers’ preconceptions concerning the unsuitability of web experiments for conducting research using response time as a dependent measure are misguided.