Bias in the eye of the beholder: Impact of pretrial publicity on jurors’ decision-making

Bias in the eye of the beholder: Impact of pretrial publicity on jurors’ decision-making

Antidefendant and antiprosecution pretrial publicity were found to have powerful effects on jurors’ impressions, evidence interpretation, and decisions, with jury type and pretrial publicity slant being the major influences. This is the bottom line of a recently published article in Psychology, Public Policy, and Law. Below is a summary of the research and findings as well as a translation of this research into practice.

Featured Article | Psychology, Public Policy, and Law | 2020, Vol. 26, No. 1, 22–35

Your bias is rubbing off on me: The impact of pretrial publicity and jury type on guilt decisions, trial evidence interpretation, and impression formation


Christine L. Ruva, University of South Florida Sarasota-Manatee
Anthony E. Coy, University of South Florida Sarasota-Manatee


Pretrial publicity (PTP) can bias jurors’ decisions. The courts often assume such bias can be ameliorated or reduced by jury deliberations. This study explored the effects of PTP (antiprosecution, antidefense, or no-PTP) and jury type (pure vs. mixed) on mock jurors’/juries’ (N = 495/96) verdicts, impressions, and trial evidence interpretation. PTP affected predeliberation verdicts, with antidefendant PTP jurors being the most likely to render guilty verdicts, and antiprosecution PTP jurors the least likely. At the jury-level, only the pure antiprosecution juries (all jurors read antiprosecution PTP) showed evidence of PTP bias by being the least likely to render guilty verdicts. Comparison of pre- and postdeliberation verdicts revealed that deliberating on pure juries increased PTP’s biasing effect on verdicts (group polarization) of antiprosecution PTP jurors, and resulted in more biased credibility ratings for antiprosecution and antidefendant PTP jurors. Regardless of jury type, no-PTP and antidefendant-PTP jurors were less likely to vote guilty after deliberations than prior to them (leniency shift), and their postdeliberation verdicts did not significantly differ. Finally, deliberating on mixed juries resulted in the transfer of PTP bias from antiprosecution PTP jurors to no-PTP jurors. Implications include that PTP biases jurors’ decisions and impressions, and the effect of deliberations on PTP bias may depend on PTP slant, jury type, and case type. Deliberations can increase bias in PTP exposed jurors deliberating on pure juries and spread PTP bias from PTP-exposed jurors to those not exposed to PTP, but additional research is needed to better understand the circumstances under which each occurs.


juror decision making, jury deliberation, pretrial publicity, impression formation evidence interpretation

Summary of the Research

“Pretrial publicity (PTP) involves media coverage of criminal or civil cases making their way to court. A large body of research has shown that exposure to PTP can bias jurors’ verdict decisions, memory for trial evidence, interpretation of trial evidence. That said, far less research has explored how the deliberations and decisions of juries exposed to PTP differ from those not exposed, as well as the influence that deliberations have on pretrial bias and ultimately verdicts. The research that has explored the deliberation process has mostly done so by exposing all jurors on the same jury to the same type/slant of PTP (pure PTP exposure), and thus cannot explain how juries made up of differently exposed jurors (mixed PTP exposure) would affect the deliberation process and the transfer or reduction of PTP bias.” (p. 22)

“The present research further explores how jury type (pure vs. mixed) affects the spread or reduction of PTP bias during deliberations. It also explores how exposure to PTP and jury type influence jurors’ evidence interpretation and their impressions of the defendant and witnesses, which have been shown to be mechanisms responsible for PTP bias.” (p. 22)

“Two theories have been used to explain how PTP (or early trial information) influences the interpretation of later information, with one focusing on jurors’ desire for a complete and coherent story (story model) and the other on jurors’ distortion of trial evidence to support a favored side (predecisional distortion theory).” (p. 23)

“According to the story model, jurors use information they bring to trial (e.g., PTP) and trial information to develop cognitive frameworks through which all subsequent trial information will be interpreted. […] Trial information that does not fit this story may be ignored, devalued, or misinterpreted, resulting in a primacy effect in which PTP has a greater influence on jurors’ decisions than trial evidence.” (p. 23)

“According to predecisional distortion theory, jurors’ do not weigh trial evidence in accordance with its true probative value. Instead, jurors’ weighting and interpretation of trial evidence is biased in the direction of their favored side (prosecution or defense), which ultimately influences their verdicts.[…] Jurors exposed to PTP may form an impression of defendants and key trial players (e.g., victims and witnesses) prior to coming to trial. Once formed, these impressions may be resistant to change and result in the biased weighting and interpretation of all subsequent information about these people (predecisional distortion and story model).” (p. 23)

“Taken together the above research suggests that PTP affects jurors’ interpretation of trial evidence and their impressions of defendants, and these biased interpretations and impressions then influence jurors’ guilt decisions. […] The courts assume that jury deliberations allow jurors to correct errors, reject irrelevant information, and control biases, resulting in jury-level decisions being less biased than juror-level decisions. Social science research suggests that these assumptions are overly optimistic, with deliberation resulting in the intensifying of PTP bias, or the failure to reduce bias.” (p. 23)

“The intensifying of individual biases after group discussion is labeled group polarization. Such polarization effects are thought to result from the social decision scheme (SDS) of majority rules. Juries composed of jurors who have been exposed to the same type of PTP (e.g., negative-defendant) are likely to have a high level of agreement in individual preferences for verdict (guilty). Therefore, deliberation under a majority rules SDS would result in a polarization of PTP bias (greater likelihood of rendering a guilty verdict post- vs. predeliberation).” (pp. 23–24)

“The present study explores the effects of PTP exposure (antiprosecution, antidefense, or no-PTP) and jury type (pure = all jurors on jury exposed to the same PTP; mixed = approximately half of the jurors exposed to one type of PTP and the other half another type) on jurors’ guilt decisions, interpretation of trial evidence, and impressions of the defendant and victim’s parents (who are the focus of the antiprosecution PTP). For the jury-level and postdeliberation analyses of the no-PTP jurors, the PTP and jury-level variables are collapsed to form the jury composition variable having six levels: three pure (antiprosecution, antidefendant, and no-PTP) and three mixed (antiprosecution-no, antiprosecution-antidefendant, and antidefendant-no-PTP) jury conditions. The study procedures involved exposing jurors to PTP and then having them come to the lab one week later to view a trial of a woman accused of killing an infant in her care, deliberate on four- to six-person juries, and provide both individual (pre- and postdeliberation) and jury-level verdicts. Following deliberations, jurors provided ratings of the trial evidence, defendant, and victim’s parents.” (p. 25)

“Participants were 495 undergraduate students (132 men and 363 women) who made up 96 juries and received extra credit in a psychology course for their participation. Participants’ ages ranged from 18 to 58 (M = 21.26, SD = 5.84). Two-hundred and 53 (51%) were White, 104 (21%) Hispanic, 70 (14%) Black/African American, 38 (8%) Asian or Pacific Islander, nine (2%) Arab, one (0.20%) American Indian or Native Alaskan, and 20 (4%) were classified as other. […] This study consisted of two experimental sessions in a laboratory setting: (a) exposure to PTP or irrelevant crime stories and (b) exposure to trial and jury deliberations.” (pp. 25–26)

“The CA v. Cummings (1994) trial video is an edited version of trial footage from a real trial involving a woman who is accused of killing a 9-month-old infant boy in her care. The defendant claims that while she was in the kitchen fixing the infant’s lunch, the infant injured his head when he fell off the couch causing the fatal injury. The trial video was edited to run 21 min and consisted of 4:15 min of pretrial judicial instruction, 1:10 min of posttrial instructions, and approximately 15 min of actual trial testimony. The trial footage included opening and closing arguments of the defense and prosecution, testimony of four doctors (three prosecution and one defense witness), direct and cross examinations of the victim’s mother and the defendant, direct examination of the victim’s father, and testimony from the defendant’s sister.” (p. 26)

“Utilizing a novel trial and PTP, this study further underscores the role that antidefendant PTP plays in undermining a defendants’ Sixth Amendment right to a fair trial, along with the role antiprosecution PTP plays in challenging the prosecution’s ability to prove guilt. Consistent with both theory (i.e., the story model; predecisional distortion theory) and research, PTP not only biased jurors’ verdicts but also their interpretation of trial evidence and impressions of the defendant and the victim’s parents. These findings underscore that early case information (i.e., PTP) can have powerful effects on jurors’ impressions of key trial players, encoding of trial evidence, and ultimately their verdicts. That said, jury type played an important role in determining the strength and spread of PTP bias during deliberation.” (p. 29)

“First, deliberations increased PTP’s biasing effect for jurors deliberating on pure juries. However, the effects differ between those exposed to antiprosecution and antidefendant PTP. Antiprosecution PTP jurors who deliberated on pure juries rated the parents lower in credibility (antiprosecution bias) and were more likely to render a not guilty verdict than antiprosecution PTP jurors deliberating on mixed juries. These effects are consistent with the group polarization effects and can be explained by the social decision scheme of majority rules.” (p. 29)

“For the antidefendant PTP jurors, there was no evidence that deliberating on pure juries resulted in an increase in bias for verdicts, but it did result in greater bias for defendant and parent credibility ratings. Thus, consistent with past research we found that deliberations, under conditions of high predeliberation consensus (pure-PTP juries), intensified PTP bias, but this increased bias was most prevalent for the antiprosecution PTP jurors.” (pp. 29–30)

“The antiprosecution PTP jurors were less likely to render a guilty verdict after deliberation, but only when deliberating on pure juries and […] this is suggestive of an increase in PTP bias for these jurors, and is supported by pure antiprosecution jurors’ posted-deliberation assessments of parent credibility and verdicts being more bias (i.e., lower parent credibility ratings and less likely to vote guilty) than those of mixed antiprosecution jurors.” (p. 30)

“In contrast, jurors who read antidefendant PTP became more lenient in their verdicts regardless of whether they deliberated on pure or mixed juries, and their postdeliberation verdicts did not significantly differ from those of no-PTP jurors. We suggest this is due to a leniency shift. Defined as a decrease in jurors’ tendency to vote guilty after deliberations relative to prior to them , an explanation provided for the leniency shift is that during deliberations the defendant protection norm and the reasonable doubt standard are emphasized.” (p. 30)

“Second, the present findings suggest the spread of bias from antiprosecution PTP exposed jurors to no-PTP jurors during deliberations. The no-PTP jurors’ guilt ratings were influenced by the antiprosecution PTP jurors they deliberated with. […] One explanation may be that the antiprosecution PTP in the current study provided an alternative explanation for who was responsible for the death of the child (the child’s parents) and exposure to antiprosecution PTP resulted in jurors coming to trial with the story that the parents are perpetrators and the wrong person is on trial.”(p. 31)

“In summary, it appears that the antiprosecution PTP had a more powerful influence than the antidefendant PTP, affecting jurors’ interpretation of trial evidence (i.e., prosecution, defense, and ambiguous facts), as well as jury-level verdicts. This antiprosecution PTP bias was also spread to no-PTP jurors during deliberations and was found to influence their guilt ratings. In addition, antiprosecution PTP was polarizing in pure groups, whereas the same was not true for antidefendant PTP (whose pure and mixed jurors showed a leniency shift). Finally, after deliberations, the antidefendant PTP jurors verdict preferences no longer significantly differed from those of no-PTP jurors.” (p. 31)

“Antidefendant and antiprosecution PTP were found to have powerful effects on jurors’ impressions, evidence interpretation, and decisions. The effect of jury deliberations on PTP bias was influenced by jury type (pure vs. mixed) and PTP slant (antiprosecution vs. antidefendant). For PTP-exposed jurors, deliberating on pure juries, as opposed to mixed juries, resulted in jurors’ having more biased impressions of the defendant and parents.” (p. 32)

“Deliberating on pure juries was also found to polarize PTP’s effect on verdicts, but only for jurors exposed to antiprosecution PTP. Jurors exposed to either antidefendant PTP or no-PTP were less likely to vote guilty after deliberations than before them, and no longer significantly differed in verdicts after deliberations. Unfortunately, deliberating on mixed juries resulted in the transfer of PTP-bias from antiprosecution PTP jurors to no-PTP jurors. These results demonstrate that the influence of deliberations on PTP bias is complicated, and PTP not only has the potential to impede a defendant’s right to a fair trial, but it may also challenge the prosecutions ability to prove guilt.” (pp. 32–33)

Translating Research into Practice

“These finding suggest that the courts, in high-profile cases, should not rely on jury deliberations to correct the bias associated with PTP exposure—doing so may result in an increase or spread of PTP bias. In addition, juror exposure to PTP should not only be the concern of the defense (fair trial), but should also be the concern of prosecutors as it can challenge their ability to prove guilt. On a positive note, antiprosecution PTP bias was reduced after deliberations in the present study, but such a reduction in bias is not commonly found and may be due to unique case and PTP factors.” (p. 32)

“The courts have PTP remedies other than deliberations and jury instruction available, with those that challenge or reduce/eliminate PTP exposure (e.g., voir dire and change of venue) having the greatest potential for success. […] The use of voir dire and change of venue as a remedies rest on the faulty assumptions that prospective jurors can assess their own bias and that judges and attorneys are able to determine whether potential jurors have the ability to be impartial. These assumptions are similar to those held by the courts for judicial instruction and deliberation, which theory and research presented above suggest are difficult, if not impossible, for PTP exposed jurors to meet. Therefore, the Court’s definition of what constitutes bias and impartiality is opposed to that of social scientists, making it difficult for the courts to effectively identify and remedy PTP bias in high-profile case.” (p. 32)

Other Interesting Tidbits for Researchers and Clinicians

“As is typical of jury simulation research, the present study had several limitations related to ecological and external validity. First, our trial stimulus, although consisting of actual trial footage, ran only 21 min, which is much shorter than actual trials. Second, juries deliberated for only 25 min. Four out of the six jury composition conditions had between two and four juries that were hung—longer deliberations would most likely reduce the number of hung juries.” (p. 32)

“Regarding external validity, our mock-jurors were university students, and therefore our findings might not generalize to other populations. […] Another limitation is that on our mixed juries, the proportions of each type of juror (i.e., antiprosecution, no, and antidefendant PTP) were roughly equal. This distribution of bias on these juries might not represent the distribution typically experienced on actual juries, and therefore may limit the generalizability of our findings.” (p. 32)

Join the Discussion

As always, please join the discussion below if you have thoughts or comments to add!

Authored by Kseniya

Kseniya Katsman is a Master’s student in the Forensic Psychology program at John Jay College of Criminal Justice. Her interests include forensic application of dialectical behavior therapy, cultural competence in forensic assessment, and risk assessment, specifically suicide risk. She plans to continue her education and pursue a doctoral degree in clinical psychology.

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