We investigated how heuristic credibility cues affected credibility judgments and decisions. Participants saw advice in comments in a simulated online health forum. Each comment was accompanied by credibility cues, including author expertise and peer reputation ratings (by forum members) of comments and authors. In Experiment 1, participants’ credibility judgments of comments and authors increased with expertise and increased with the number of reputation ratings for supportive ratings and decreased with number of ratings for disconfirmatory ratings. Also, results suggested that the diagnosticity (informativeness) of credibility cues influenced credibility judgments. Using the same credibility cues and task context, Experiment 2 found that when high-utility choices had low credibility, participants often chose alternatives with lower utility but higher credibility. They did this more often when less utility had to be sacrificed and when more credibility was gained. The influence of credibility and utility information on participants’ choices was mediated by their explicit credibility judgments. These findings supported the predictions of a Bayesian belief-updating model and an elaboration of Prospect Theory (Budescu, Kuhn, Kramer, & Johnson, 2002). This research provides novel insights into how cues including valence and relevance influence credibility judgments and how utility and credibility trade off during decision making.

Objective: We investigated whether intelligent advanced warnings of the end of green traffic signals help drivers negotiate the dilemma zone (DZ) at signalized intersections and sought to identify behavioral mechanisms for any warningrelated benefits.Background: Prior research suggested that warnings of end of green can increase slowing and stopping frequency given the DZ, but drivers may sometimes respond to warnings by speeding up. Method:In two simulator studies, we compared six types of roadway or in-vehicle warnings with a no-warning control condition. Using multilevel modeling, we tested mediation models of the behavioral mechanisms underlying the effects of warnings.Results: In both studies, warnings led to more stopping at DZ intersections and milder decelerations when stopping compared with no warning. Drivers' predominant response to warnings was anticipatory slowing on approaching the intersection, not speeding up. The increased stopping with warning was mediated by increased slowing. In Study 1, anticipatory slowing given warnings generalized to green-light intersections where no warning was given. In Study 2, we found that lane-specific warnings (e.g., LED lights embedded in each lane) sometimes led to fewer unsafe emergency stops than did nonlane-specific roadside warnings.Conclusion: End-of-green warnings led to safer behavior in the DZ and on the early approach to intersections. The main mechanism for the benefits of warnings was drivers' increased anticipatory slowing on approaching an intersection. Lane-specific warnings may have some benefits over roadside warnings.Application: Applications include performance models of how drivers use end-of-green warnings, control algorithms and warning displays for intelligent intersections, and statistical methodology in human factors research.

AdministrationThis simulator experiment compares driver behavior in the Dilemma Zone (DZ) on a 4-lane divided highway using three types of warnings of impending traffic signal end of green to no advance warning (control). The DZ occurs when onset of a yellow signal occurs at a temporal interval before an intersection such that stopping or proceeding through the intersection has roughly equal perceived risk. Two of the systems allowed lane specific warnings and one did not. Sixty-nine participants drove a total of 45 minutes in the right lane of on a multilane highway with 36 intersections. On approach to 10 of the intersections, participants were placed in the DZ. For 6 other intersections drivers (still in the right lane) were exposed to a warning not intended for them but for a driver behind them in the left lane. Participants in all warning conditions received warnings 1.5 s or 3.0 s in advance of the end of green. Drivers in all of the advanced warning conditions stopped at the DZ intersections significantly more often than control condition drivers. When stopping at intersections, drivers given an advanced warning decelerated more gradually than those that had no warning. One exception was when drivers misinterpreted the left lane warning as intended for them and therefore decelerated rapidly to stop at the intersection.

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