Eric T. Chancey

The Role of Trust as a Mediator Between System Characteristics and Response Behaviors

Objective: The purpose of the current work was to clarify how subjective trust determines response behavior when interacting with a signaling system. Background: In multiple theoretical frameworks, trust is acknowledged as a prime mediator between system error characteristics and automation dependence. Some researchers have operationally defined trust as the behavior exhibited. Other researchers have suggested that although trust may guide operator responses, trust does not completely determine the behavior. Method: Forty-four participants interacted with a primary flight simulation task and a secondary signaling system task. The signaling system varied in reliability (90%, 60%) and error bias (false alarm, miss prone). Trust was measured halfway through the experimental session to address the criterion of temporal precedence in determining the effect of trust on behavior. Results: Analyses indicated that trust partially mediated the relationship between reliability and agreement rate. Trust did not mediate the relationship between reliability and reaction time. Trust also did not mediate the relationships between error bias and reaction time or agreement rate. Analyses of variance generally supported specific behavioral and trust hypotheses, indicating that the paradigm employed produced similar effects on response behaviors and subjective estimates of trust observed in other studies. Conclusion: These results indicate that strong assumptions of trust acting as the prime mediator between system error characteristics and response behaviors should be viewed with caution. Application: Practitioners should consider assessing factors other than trust to determine potential operator response behaviors, which may be more predictive.

Trust and the Compliance–Reliance Paradigm: The Effects of Risk, Error Bias, and Reliability on Trust and Dependence

Objective: This study provides a theoretical link between trust and the compliance–reliance paradigm. We propose that for trust mediation to occur, the operator must be presented with a salient choice, and there must be an element of risk for dependence. Background: Research suggests that false alarms and misses affect dependence via two independent processes, hypothesized as trust in signals and trust in nonsignals. These two trust types manifest in categorically different behaviors: compliance and reliance. Method: Eighty-eight participants completed a primary flight task and a secondary signaling system task. Participants evaluated their trust according to the informational bases of trust: performance, process, and purpose. Participants were in a high- or low-risk group. Signaling systems varied by reliability (90%, 60%) within subjects and error bias (false alarm prone, miss prone) between subjects. Results: False-alarm rate affected compliance but not reliance. Miss rate affected reliance but not compliance. Mediation analyses indicated that trust mediated the relationship between false-alarm rate and compliance. Bayesian mediation analyses favored evidence indicating trust did not mediate miss rate and reliance. Conditional indirect effects indicated that factors of trust mediated the relationship between false-alarm rate and compliance (i.e., purpose) and reliance (i.e., process) but only in the high-risk group. Conclusion: The compliance–reliance paradigm is not the reflection of two types of trust. Application: This research could be used to update training and design recommendations that are based upon the assumption that trust causes operator responses regardless of error bias.

Effects of Alarm Modality and Alarm Reliability on Workload, Trust, and Driving Performance:

As roads are getting more congested, the rate of automobile crashes due to driver error is also rising. Driving is an attention demanding task. The automobile industry has developed collision avoidance warning systems to increase situation awareness and roadway safety. Different modalities of alarms could be used to increase drivers’ situation awareness. The current study is a preliminary analysis of the effects of alarm reliability (70% & 90%) and alarm modality (auditory & tactile) on driver performance, trust in alarms, and perceived workload. Participants (n=5) drove in a simulated environment. The results showed that drivers had fewer collisions in the tactile condition than the auditory condition. The findings of this research can inform which alarm modality is effective in improving driver performance and how practitioners can use this information to improve collision avoidance warning systems to increase roadway safety.

Vibrotactile Stimuli Parameters on Detection Reaction Times

Signaling system designers are leveraging the tactile modality to create alarms, alerts, and warnings. The purpose of this research was to map detection reaction times (RT) toward tactile stimuli with various parameter manipulations. We employed a 3 (wave form) × 3 (inter-pulse interval) × 3 (envelope) within subjects design. The dependent measure was detection RT. Twenty participants (15 female) responded to 270 tactile stimuli. ANOVAs indicated three two-way interactions. Generally, shorter inter-pulse intervals led to quicker RT and the fade-in envelope led to longer RT, when compared to envelopes starting at the maximum amplitude. Square and sinusoidal waves tended to prompt quicker RT than the noise wave. The strength of these relationships, however, depended upon the presence of the other parameters. Designers can use the results of this study to effectively and appropriately assign tactile parameter manipulations to signals that require varied levels of response urgencies.

Reliability of a Cued Combat Identification Aid on Soldier Performance and Trust

Personal combat identification (CID) aids have been developed to assist Soldiers in the appropriate allocation of lethal force. Because of the dynamic nature of the battlefield, CID aids may be situationally unreliable. The purpose of the current study was to explore the effects of varying the reliability levels of CID aids on Soldier performance using a simulated marksmanship trainer. Twelve Army ROTC students and two active duty USMC volunteers engaged in three separate “shoot/don’t-shoot” tasks using three separate simulated CID aids of different reliability levels (90%, 75%, and 60%). Improved target identification accuracy and reaction time were observed when the participants used more reliable CID aids. Higher trust ratings were associated with the more reliable aids. The results suggest that these types of automated aids may be useful in terms of both lethality and as a fratricide prevention tool, provided there is a high reliability associated with the system.

The Effects of Alarm System Reliability and Reaction Training Strategy on Alarm Responses

Research has shown that humans react predictably to unreliable alarm systems and that some variables may mediate the relationship between alarm reliability and performance. Researchers have identified alarm design and operator training strategies to improve task operator reactions. The goal of the current project was to train task performers to use sensor activity patterns to improve subsequent alarm reactions. Eighty participants monitored a simulated security screen while completing a primary word search task. During low- and high-alarm reliability sessions motion sensors activated in various rooms, requiring acknowledgement. Alarms then activated, requiring participants to respond or ignore them. Participants received spatial, temporal, single sensor, or no training. They were also aware of alarm system reliability levels. Analyses revealed quicker reactions for trained participants and to high reliability alarms. Results suggest that single sensor training was most beneficial and that participants who received temporal training relied on alarm reliability as a cue.

The Role of Trust as a Mediator between Signaling System Reliability and Response Behaviors

Alarm researchers have frequently operationally defined operator trust as response rate and reaction time to agree with the signaling system. The purpose of the current study was to investigate the role of subjective estimates of trust in the relationship between signaling system reliability and response behaviors. Method: Using a sample of 56 college students, we tested the effects of reliability (20% and 40%) on response frequency, alarm reaction time, and subjective trust, using an alarm-based task. Results: Supporting expectations, we found that the more reliable system led to higher response frequency and higher ratings of trust. We did not find, however, that trust mediated the relationship between reliability and response rate. Considering these findings, the minimally trained participants we tested may not have relied on trust. Alternatively, our trust assessments may have lacked specificity for the experimental task. Replication efforts should focus on task experts and refined trust assessment techniques.

False Alarms vs. Misses: Subjective Trust as a Mediator between Reliability and Alarm Reaction Measures

Research suggests that signaling system false alarms tend to affect operator compliance, whereas misses tend to affect operator reliance. Conceptually, false alarms and misses affect compliance and reliance via independent cognitive processes, assumed to be two types of trust. The purpose of this study was to test for these underlying processes using a subjective estimate of trust. Method: Using a sample of 44 college students, we tested for trust as a mediator between reliability (90%, 60%) and reliance, compliance, and response rate, for a false alarm prone (FP) system and a miss prone (MP) system. Results: As predicted, trust mediated the relationships between reliability and signal compliance and response rate, but only for the FP system. Additionally, the MP system more directly affected reliance, whereas the FP system more directly affected compliance. Applications of this work indicate that designing for trustable signaling systems may be more important for FP systems.

An investigation of training strategies to improve alarm reactions

Researchers have suggested that operator training may improve operator reactions; however, researchers have not documented this for alarm reactions. The goal of this research was to train participants to react to alarms using sensor activity patterns. In Experiment 1, 80 undergraduates monitored a simulated security screen while completing a primary word search task. They received spatial, temporal, single sensor, or no training to respond to alarms of differing reliability levels. Analyses revealed more appropriate and quicker reactions when participants were trained and when the alarms were reliable. In Experiment 2, 56 participants practiced time estimation by simple repetition, performance feedback, or performance feedback and temporal subdivision. They then reacted to alarms based on elapsed time between sensor activity and alarm onset. Surprisingly, results indicated that participants did not benefit differentially from temporal interval training, focusing instead on advertised system reliability. Researchers should replicate these findings with realistic tasks and real-world complex task operators.

Training time estimation to improve alarm reactions

Prior researchers have demonstrated that training may be an effective strategy for improving operator reactions to alarm systems with less than perfect reliability. Of the training strategies tested, recognition of temporal patterns in prior sensor activations seems to offer the greatest promise for improving the speed and appropriateness of subsequent alarm reactions. The current research was completed to clarify which of three temporal interval training methods leads to the most appropriate alarm reactions. Fifty-six undergraduates evaluated whether alarms occurring after sensor activations were true or false, based on elapsed time between the sensor signals and the alarm signals. Participants completed five training sessions to learn to estimate time intervals using simple repetition training, performance feedback, or performance feedback plus subdivision cues. Contrary to expectations, results indicated that participants did not benefit differentially from temporal interval training. Differences between pre- and posttest interval estimation performance was similar among groups, and training groups performed comparably when reacting to signals. Participants generally focused on advertised alarm system reliability, responding more appropriately and more quickly to lower reliability alarms. Future researchers and designers should replicate these findings with realistic tasks and real-world complex task operators to determine their generalization.