- Ph.D. 1969, University of California, Los Angeles
M.A. 1966, University of California, Los Angeles
B.A. 1965, University of California, Los Angeles
Specialty Areas: Social Psychology, Social Cognition, Psychology and Law.
- Psy 321 - Experimental Psychology
Psy 345 - Social Psychology
Psy 386 - Psychology and Law
Selected Publications and Presentations
Shaw, J.I., & Steers, W.N. (2001). Gathering information to form an impression: Attribute categories and information valence. Current Research in Social Psychology, 6(1), 1-17.
This study investigated how target-relevant attribute categories and information valence affect information search during impression formation. Equal numbers of male and female participants (N=270) formed a likability impression of a male or female target person by accessing positive and/or negative information about the target person's appearance and/or traits. The information environment permitted either unicategorical (appearance or trait) or bicategorical (appearance and trait) searches and the information items were either univalent (all positive or all negative) or bivalent (half positive and half negative). As predicted, perceivers accessed more appearance than trait attributes in the unicategorical searches and more trait than appearance attributes in the bicategorical searches (p < .0001). Univalent negative searches were shorter than univalent positive searches (p < .0001), confirming a negativity effect. Bivalent searches restored search length compared to univalent negative searches, with this effect occurring only for traits in unicategorical searches (p < .0001). Results were interpreted in terms of a fundamental preference for more stable trait information, with appearance information used primarily to enable a trait inference.
Skolnick, P., & Shaw, J.I. (2001). Effects of criminal motivation, ability, and opportunity on mock jurors= verdicts. In Roesch, R., Corrado, R.R., & Dempster, R.J. (Eds.). Psychology in the courts: International advances in knowledge. London: Routledge, 97-106.
A study examined the effects on mock jury decision-making of defendant motivation, physical ability, and opportunity to commit a crime by manipulating each in a 2 x 2 x 2 factorial design. 112 jury-eligible participants were randomly assigned to read one of eight versions of a hypothetical murder scenario and were each asked to render a verdict, to recommend a sentencing option, and to make other evaluative judgments of the defendant. It was hypothesized that all three factors would be important to establish guilt. However, since motivation is merely a sufficient condition for guilt, whereas ability and opportunity are necessary conditions, motivation was expected to have an effect only when both ability and opportunity were demonstrated. Log linear analysis confirmed that all three factors influenced mock jurors' verdicts and sentencing options. While the expected interaction between motivation and the other two factors was not obtained for criminal verdicts, sentencing options were affected by motive only when opportunity was also present. Analysis of variance confirmed that motive, ability, and opportunity also affected judgments of criminal responsibility, but personal evaluations of the defendant were influenced only by evidence of motivation. Results were discussed in terms of implications of these three factors for prosecutors and defense attorneys in criminal proceedings.
Skolnick, P., & Shaw, J.I. (2001). A comparison of eyewitness and physical evidence on jury decision-making. Criminal Justice and Behavior, 28(5), 614-630.
Two studies compared the effectiveness of eyewitness testimony and physical evidence on mock juror decision-making. Jury-eligible participants were randomly assigned to read one of eight versions of a hypothetical murder scenario and were each asked to render a verdict, to recommend a sentencing option, and to make other evaluative judgments of the defendant. In Study 1 (N=90), either eyewitness testimony or physical evidence was presented, whereas in Study 2 (N=120), both types of evidence were presented together. Additionally, both studies varied the strength of evidence presented. Log linear analysis confirmed that mock jurors' verdicts and evaluative judgments were influenced to a greater extent by physical evidence than by eyewitness testimony. Strong evidence produced more guilty verdicts than weak evidence. However, combining strong evidence of both types was no more effective than presenting strong evidence of either one. Results were discussed in terms of implications of these factors for prosecutors and defense attorneys in criminal proceedings.
Shaw, J.I., & Steers, W.N. (2000). Negativity and polarity effects in gathering information to form an impression. Journal of Social Behavior and Personality, 15(3), 399-412.
A study was conducted to examine the effects of information valence and extremity on information search during impression formation. One hundred and twenty undergraduates (half men, half women), formed a likeability impression of a target person by searching appearance and trait information that varied in valence and extremity. Searches were shorter with negative vs positive information (negativity effect) and with extreme vs more neutral information (polarity effect). A participant sex x valence x extremity interaction indicated that men's information searches displayed the negativity effect only with extreme information, whereas women's searches displayed the effect regardless of information extremity. Results were discussed in terms of a risk-avoidance impression formation strategy.
Shaw, J.I., & Skolnick, P. (1999). Weapon focus and sex differences in eyewitness identification: Arousal vs salience. Journal of Applied Social Psychology, 29, 2328-2341.
Weapon focus and sex differences in eyewitness accuracy: Arousal vs salience Abstract Competing theories of arousal vs salience and object enhancement vs reduced perceptual processing as explanations for the weapon focus effect in eyewitness identification were examined. Two hundred male and female students viewed a videotape of a male or female intruder rudely barging into a classroom while carrying one of several objects (a book, gun, or an unusual object) and demanding to know the whereabouts of another student. Feature accuracy recall of both the intruder and the object were assessed on a postexperimental questionnaire. Results supported the salience and reduced perceptual processing hypotheses suggesting that weapon focus may be a special instance of a more general salient object effect. The pattern of findings were different when the eyewitness and the intruder were of the same sex than when the sexes were opposite suggesting limitations on the weapon focus effect. An own sex bias in eyewitness identification was replicated when no weapon or unusual objects distracted eyewitnesses, but was reversed when a weapon or unusual objects were present.
Gold, G.J., & Shaw, J.I. (1999). Causal chaining: The structure and complexity of accounts. Journal of Social Behavior and Personality, 13(4), 651-666.
Causal chaining: The structure and complexity of accounts Abstract Investigations into perceptions of causality typically presume simple causal explanations. In contrast, this study allowed account complexity and structure to vary. Eighty-nine participants were asked to choose the causes necessary to explain one of four outcomes differing in severity and valence of consequences. They had eight possible causes to choose from that varied along dimensions of locus, stability, and controllability. Most explanations were three causes in length arranged in a temporal chain. Internal, stable, and controllable causes were used more than external, unstable, and uncontrollable causes. Results were consistent with the fundamental attribution error and the need for predictability and control. This suggests that complex explanations of necessary causality may be more common than previously assumed, but that the dimensions used for explanation remain consistent with established theory.
Skolnick, P., & Shaw, J.I. (1997). The O.J. Simpson criminal trial verdict: Racism or status shield? Journal of Social Issues, 53(3), 505-518.
The O.J. Simpson criminal trial verdict: Racism or status shield? Abstract A simulation study investigated the factors which may have led the jury in the O.J. Simpson criminal trial to an acquittal verdict. Black and White mock jurors read a transcript of a murder trial which varied the defendant’s race (Black or White) and celebrity status (high or low). Results confirmed a "Black Racism” hypothesis since Black jurors favored Black over White defendants by voting not guilty more often, recommending more lenient sentences and judging them more positively. In contrast, White jurors did not differentiate between Black and White defendants. Status of the defendant did not affect verdicts or sentencing but did influence evaluative judgments. These results suggest that the O.J. Simpson verdict was likely to have been more influenced by race rather than his celebrity status. Limitations of the findings of this mock jury study were discussed.
My research program in social cognition includes (1) the factors that affect information acquisition during impression formation, and (2) the structure and dimensions of causal explanations. Our previous work has found that persons prefer to search trait and behavior attributes significantly more than appearance and demographic attributes when forming an impression of a target person. Although this search pattern was obtained for all gender combinations of participant-target pairs, male participants accessed more appearance information about female targets than did any other participant-target combination. A subsequent investigation replicated the preference for trait over appearance information in multicategorical searches (both appearance and trait information available) but found a preference for appearance over trait information in unicategorical searches (only appearance or trait information available). This finding was interpreted in terms of a fundamental preference for more stable trait information and that other information such as appearance, behavior, and demographic data is used primarily to enable a trait inference. Our more recent research investigates the effects of information valence and extremity in information gathering. We have found that both negative and extreme information shorten information search behavior suggesting that social perceivers adopt a risk-avoidance impression formation strategy.
Our work on the structure and dimensions of perceived causality examines how naive perceptions of performance outcomes are structured in temporally linked causal chains that differ in terms of causal locus (internal vs external), variability, and controllability. We found that most explanations of performance outcomes are three causes in length arranged in a temporal chain. Internal, stable' and controllable causes are used more than external, unstable, and uncontrollable causes. These results are consistent with the fundamental attribution error and the need for predictability and control. It is suggested that complex explanations of necessary causality may be more common than previously assumed, but that dimensional structure remains consistent with established theory. Additional research has examined how complex causal explanations are structured across different domains, including achievement, accidental, and interpersonal behaviors. Perceivers were asked to link together sequential causes to explain positive and negative outcomes in each of these domains. Accidents and events with positive outcomes produced the fewest and shortest chains. However, positive accidents produced longer chains than negative accidents. More explanations were terminated at a dispositional than at a situational node. Although judgments of outcome foreseeability were lowest for accidents and for positive rather than negative utcomes, negative accidents were judged the most foreseeable. Results indicated that patterns of complex causality depend on the behavioral domain considered.
My research program in psychology and law has focused on factors that influence mock jury decision-making, including the presence of a weapon during a crime, the socioeconomic status of a criminal defendant, and the type of evidence introduced against the defendant. In a series of investigations we have found that any unusual object (including a weapon) that is carried by a crime perpetrator reduces the accuracy of eyewitness descriptions. We have also found that high status defendants are subjected to harsher or weaker sanctions by mock jurors, depending on whether the crime is related to the defendant’s status. When unrelated, defendants enjoy a “status shield” effect with lesser sanctions and when related, they endure a “status liability” effect with increased sanctions. Finally, we have observed that a criminal defendant’s motive, ability, and opportunity each affect mock jury verdicts and that physical evidence against a defendant produces stronger sanctions than eyewitness evidence. The most recent work in this research program has focused on juror training to correct the many deficiencies associated with the present jury system