TWENTY HEBREW-SPEAKING MALE UNIVERSITY STUDENTS SERVED AS SUBJECTS. THE EFFECT OF STRESS-PRODUCING STIMULI ON PSE RECORDINGS WAS EXAMINED UNDER TWO CONDITIONS: LOW STRESS (CARD TEST) AND HIGH STRESS (HORROR PICTURE TEST) SITUATIONS. SIX DIFFERENT CARDS WERE USED AS STIMULI FOR THE CARD TEST AND A SERIES OF NINE COLOR SLIDES SHOWING MUTILATED CORPSES OF ROAD ACCIDENT VICTIMS WERE USED AS STRESS-AROUSING STIMULI FOR THE HORROR PICTURE TEST. A TOTAL OF 17 SCENIC COLOR SLIDES SERVED AS THE CONTROL CONDITION. VERBAL RESPONSES WERE RECORDED BY A MICROPHONE CONNECTED TO A TAPE RECORDER. LOW RELIABILITY AND VALIDITY SCORES OBTAINED IN THE LABORATORY TESTS DID NOT SEEM TO SUPPORT THE CLAIM FOR PSE VALIDITY. TO TEST THE HYPOTHESIS THAT PSE STRESS RESPONSES MIGHT BE MORE ACCURATELY DETECTED IN FIELD SITUATIONS, A SECOND EXPERIMENT WAS CONDUCTED. THE RELIABILITY AND VALIDITY OF PSE CHART EVALUATIONS OF THE VERBAL RESPONSES MADE BY CRIMINAL SUSPECTS UNDERGOING STANDARD POLYGRAPH INTERROGATIONS WERE EXAMINED. A TOTAL OF 56 HEBREW-SPEAKING MALE CRIMINAL SUSPECTS SERVED AS SUBJECTS. FINDINGS FOR ALL TESTS AND FOR THE TWO ANALYSES SHOWED AN INVERSE RELATIONSHIP BETWEEN THE NUMBER OF SUBJECTS INVOLVED AND THE MAGNITUDE OF THE RELIABILITY AND VALIDITY SCORES. AN INVERSE RELATIONSHIP WAS ALSO FOUND BETWEEN STRESS LEVEL AND PERFORMANCE SCORES. IN NO TEST OF THE PRESENT STUDY WAS THE PSE-CRITERIA CORRESPONDENCE HIGH ENOUGH OR THE DIFFERENCES BETWEEN PSE EVALUATIONS AND CHANCE DECISIONS AND BETWEEN CORRECT AND INCORRECT EVALUATIONS SIGNIFICANT. THUS, THE CLAIM FOR PSE VALIDITY AS A DETECTOR OF PSYCHOLOGICAL STRESS IS NOT SUPPORTED. FURTHER RESEARCH IS PLANNED TO TEST THE DIFFERENTIAL EFFECTS OF INSTRUMENTAL IMPROVEMENTS, PROCEDURAL CHANGES, AND VARIOUS CHART EVALUATION TECHNIQUES ON CHART EVALUATION ACCURACY. GRAPHS, TABULAR DATA, AND FOOTNOTES ARE ATTACHED. (AOP)