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

Four investigations of the affect-pupil size relationship are reported here as attempts to test Hess's (1965) attraction-dilation and aversion-constriction hypotheses. In the first two studies, no evidence was found for a relationship between pupil size and frequency of exposure to a stimulus as defined by Zajonc (1968). However, it was observed that the stronger a stimulus was rated in terms of affect (like-dislike), whether positive or negative, the larger the pupil size. Pupil size at the neutral point was not smallest, as expected, but was elevated, relative to the points adjacent to it. Two additional studies, using a pseudo task which induced feelings of success or failure, confirmed the previous findings. A positive relationship was found between pupil size and affect intensity, and again, elevated pupil size at the neutral points. There was no evidence of constriction to any stimulus, positive or negative, in any of the four studies. It was concluded that pupil size is linearly related to the intensity continuum of affect and curvilinearly related to its valence (positive-negative) continuum.

An attempt is made to review all of the relevant research since 1960 on the relationship between pupil size and positive and negative affect It is judged that Hess' (1965) notion of dilation to pleasant stimuli and constriction to unpleasant stimuli is not substantially supported in the literature. The most consistent finding relates greater dilation to increases in the intensity of stimulation, whether positive or negative; that is, pupillary activity is linearly related to the intensity continuum of affective stimulation, but curvilinearly related to the valence (positive-negative) continuum. The suggestion is made that results of studies using visual stimuli may be artifactual due to contrast effects. Essai de revue critique des recherches ayant porte, depuis 1960, sur la relation entre le diametre pupillaire et les affects positifs et negatifs. n est allegue que la notion de Hess (1965) voulant que la pupille se dilate en presence de stimuli agreables et se contracte en presence de stimuli desagreables n'est pas substantiellement confirmee dans les faits. Les donnees les plus consistantes montrent une relation entre dilatation et accroissement d'intensitS de la stimulation (positive ou negative); en fait, la relation est lineaire entre I'activit6 pupillaire et l'intensitg de la stimulation affective, mais la relation est curvilineaLre entre l'activitt pupillaire et la valence (positive ou negative) de la stimulation. U est suggere que des effets de contraste peuvent avoir introduit des artefacts dans les etudes utilisant des stimuli visuels.

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