A technique developed by researchers at the University of Utah beginning in the 1970s, and was initially influenced by the Backster Zone Comparison Test. It differs from other ZCT formats in that the relevant questions are not bracketed by comparison questions. Other unique characteristics of the UPLT are: the inclusion of the photoplethysmograph; rotation of the probable-lie questions; recording of five charts when the test would be inconclusive at three charts; and symmetrical cutoffs of +/-6. The UPLT has been validated in mock crime analog studies and has more peer-reviewed publications supporting it than any other probable-lie technique. More recently the developers of the Utah technique have also endorsed the use of directed-lie questions in place of probable-lie questions. See: Handler, (2006); Raskin & Honts (2002).
