Zweifel, Robert L.

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Northwestern University Illinois, School of Law: Scholarly Commons

Journal of Criminal Law and CriminologyVolume 43 | Issue 2 Article 141952Adaptation of the Opaque Projector to LieDetector DemonstrationRobert L. ZweifelFollow this and additional works at: https://scholarlycommons.law.northwestern.edu/jclcPart of the Criminal Law Commons, Criminology Commons, and the Criminology and CriminalJustice CommonsThis Criminology is brought to you for free and open access by Northwestern University School of Law Scholarly Commons. It has been accepted forinclusion in Journal of Criminal Law and Criminology by an authorized editor of Northwestern University School of Law Scholarly Commons.Recommended CitationRobert L. Zweifel, Adaptation of the Opaque Projector to Lie Detector Demonstration, 43 J. Crim. L. Criminology & Police Sci. 256(1952-1953)ADAPTATION OF THE OPAQUE PROJECTOR TO LIEDETECTOR DEMONSTRATIONRobert L. ZweifelThe author is a graduate student in the Depatrtment of Police Science, The StateCollege of Washington, Pullman, specializing in Instrumental Deception Detection.Mr. Zweifel holds a B.S. degree in Police Science from Washington State and inaddition to his academic work has assisted local law enforcement agencies in liedetector problems.-EDITOR.In taking the lie detector out of the laboratory or test room for thepurpose of instructing a class of students or demonstrating it before anaudience, certain problems are presented. Generally speaking, the sizeof the group must be restricted to the number that can convenientlyassemble around the instrument. Even a small group clustered aroundthe instrument while it is in operation may invalidate the test results tothe extent that an erroneous impression is left with the audience con-cerning the value of the instrument.The problem was how to make it possible for a large number ofindividuals to view the lie detector in operation and at the same timereduce the interference with testing procedure. A Bausch & Lombopaque Balopticon Projector was converted so that the machine couldbe placed under the projector in such a manner that the chart andrecording needles would be projected in motion upon a screen. (Seefigure 1.) Examination revealed that in order to accomplish the de-sired results, a portion of the permanent base of the Balopticon Pro-jector would have to be removed, and a substitute base constructedas follows.Six main pieces make up the substitute base. (See figure 2.) Thetwo sides are 12" x 24" rectangles, slightly tapered in the upper frontto coincide with the angle of the front of the Balopticon Projector. Acircular hole is made in the left side to accommodate the forced aircirculation intake in the projector. A rectangular slot is made in the leftside 9Y4" x 1134", leaving a strip 4" wide at the top bridging theslot. Directly opposite this slot, on the right side, is a correspondingslot 9" x 934", leaving a 3" strip at the top. A piece of strap iron13 Y4" long is bolted near the bottom of the slot on the right side forstructural strength. Exactly 5Y2" from the top edges of the sides andflush with the sides of the slots, 3" x 8" pieces are attached. These twopieces serve the dual purpose of strengthening the substitute base andas supports for the original base when the projector is not being usedwith the lie detector. The front of the base is 6 4 " x 8", and the frontTHE OPAQUE PROJECTORFigure 1.of the projector rests on the top edge. The back of the base is 8" x11 8", and the top edge serves as a rest for the back of the projector.Two strips 8" x Y" x 15" are attached on the inner surface of eachside at a level corresponding to the height of the back of the base;SCALEFigure 2.19521ROBERT L. Z]'EIFELthese serve as supports for the sides of the projector. All joints areput together with glue and strengthened with screws.All of the material used in the construction of the substitute basecan be of 4" material. Finished pine is ideal because of ease in work-ing, and it can be nicely finished with stain and varnish or shellac.In separating the original base from the projector, an angle must becut that runs between the edge of the trim of the forced air circulationintake, just missing the structural supports at the bottom of the re-moved base.Another problem that presented itself was the intense heat of theBalopticon Projector which was directed upon the chart drive unit ofthe lie detector. To alleviate this condition, a filter consisting of 6plates of ordinary window glass was placed between the light source ofthe projector and the machine. These plates, 6" x 9", are slightlylarger than the opening in the bottom of the projector and can be laidloosely in the bottom.The net result is a motion picture on the screen showing the chartdrive and recording needles in motion. In actual practice, this graphicportrayal of lie detector technique has proven very effective in groupsituations. It may also offer possibilities in determining the diagnosticvalue of visual stimulus on the subject during actual deception tests.[Vol. 43

Adaptation of the Opaque Projector to Lie Detector Demonstration

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Adaptation of the Opaque Projector to Lie Detector Demonstration

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