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WCM Factor7 Definition Operational Definition Likeability The degree to which an expert is friendly, respectful, kind, well-mannered, and pleasant.10,17,23 High likeability: consistent use of “we” or “us” when discussing members of the scientific community or humanity as a whole, moderate levels of smiling, modest statements and conclusions (e.g., “relatively certain” or “we do not know everything there is to know in psychology”), consistent eye contact with lawyer and jury, and informal speech (i.e., limited technical jargon and use of surnames of parties in the courtroom).10,17,23 Low likeability: no use of “we” or “us”, no smiling, excessive statements of certainty of conclusions, inconsistent eye contact, use of highly technical jargon, and frequent formal references (e.g., “the client”, “the defendant”).10,17,23 Knowledge The degree to which an expert is perceived to be well informed, competent, or perceptive and to possess or exhibit intelligence, insight, understanding, or expertise.10, Current Study High knowledge: strong educational credentials (e.g., board certification, history of academic publication in case-relevant area of expertise (educated at Yale, American Board of Forensic Psychology certified, history of relevant publications), solid relevant clinical and research experience (researches risk assessment, has conducted over 100 clinical risk assessments over 14 years), consistent clarity and substantive content of communication, moderate assertiveness (e.g., “as far as I know I've never been wrong” when queried about awareness of clinician error), self-proclaimed expertise (e.g., “In my expert opinion…”), and demonstrates familiarity with the case (e.g., multiple interviews with the defendant).10, Current Study Low knowledge: no mention of educational credentials, minimal relevant experience (e.g., little experience or nonrelevant experience [two years as a psychotherapist and no previous risk assessment experience]), inconsistent clarity and substantive content of communication, low assertiveness (e.g., “no” when queried about awareness of clinician error), no self-proclaimed expertise, inadequate familiarity with the case (e.g., one short interview with the defendant the week the case went to trial).10, Current Study Confidence The degree of demonstrable self-assurance expert witnesses have in their general ability on the stand.24 Low confidence: quivering tone of voice, dysfluencies in speech, vacillating pace of speech, corrections, breaks in the flow of words, postural awkwardness, fixed eye contact, saying “you know” to seek assurance, asking for repetition of questions, and signs of anxiety and nervousness.24 Medium confidence: moderate and stable tone of voice, clarity in speech, moderately paced speech, willingness to acknowledge a degree of certainty (“I am reasonably certain”), smooth narrative statements, good posture and straight back, comfort and poise, consistent eye contact, accurate hearing, and appropriate responses.24 High confidence: loud and strong tone of voice, assertive speech and mannerisms, rapidly paced speech, always and all statements (“I am certain”), good posture/leaning forward, high fluency of speech.24 Trustworthiness Not yet defined as part of the WCM. Has not yet been operationally defined within the WCM. Characteristic Citation Substantive content of communication Ware, Williams, 19753 Assertiveness Kern, 19822 Clarity of communication Champagne et al., 199125 Educational credentials Champagne et al., 199125 Familiarity with the facts of the case Champagne et al.,199125 Relating testimony content to physical evidence and other witnesses Champagne et al., 199125 Sufficient experience relevant to the content of the communication Brodsky, 19914 Testimony's consistency with common sense Sundby, 199733 Academic degrees obtained, positions held, populations evaluated or treated, professional certifications or licensure, board certification, membership in professional organizations, professional publications, prior court experience as an expert, and honors and awards Melton et al. 200726 Self-proclaimed credentials Lee, 20071 Dependent Variables Manipulation Check WCS trustworthiness WCS confidence WCS likeability Future violence likelihood* Sentencing decision† WCS knowledge High knowledge (n = 72) 36.39 (10.04) 39.18 (9.08) 35.43 (8.55) 77.08 (16.41) −0.20 (1.57) 39.83 (8.53) Male expert (n = 35) 35.97 (9.43) 39.74 (8.63) 36.83 (6.20) 75.29 (18.13) −0.32 (1.82) 39.97 (7.62) Female expert (n = 37) 36.78 (10.71) 38.65 (9.57) 34.11 (10.21) 78.78 (14.66) −.08 (1.32) 39.69 (9.48) Low knowledge (n = 64) 36.26 (8.27) 38.02 (7.65) 39.29 (8.15) 74.80 (16.08) 0.12 (1.52) 35.97 (9.33) Male expert (n = 32) 34.78 (9.30) 37.38 (7.98) 39.71 (8.96) 75.41 (16.12) −0.29 (1.76) 34.41 (10.62) Female expert (n = 32) 37.63 (7.08) 38.53 (7.49) 38.84 (7.51) 74.19 (16.28) 0.53 (1.13) 37.53 (7.70) Combined knowledge Male expert 35.40 (9.32) 38.61 (8.35) 38.21 (7.72) 75.34 (17.07) −0.31 (1.78) 37.31 (9.52) Female expert 37.21 (9.09) 38.64 (8.55) 36.36 (9.24) 76.65 (15.49) −0.21 (1.26) 38.68 (8.67) WCS, Witness Credibility Scale factors.
↵* Jurors' ratings of the percent chance that the defendant would engage in future violent acts (agreement with the expert's opinion of a high likelihood).
↵† Negative scores denote higher likelihood of the death penalty, and positive scores denote higher likelihood of a life sentence without parole.
