Randall D. Spain

Towards an Empirically Developed Scale for System Trust: Take Two

Research on human trust in automated systems has been frequently limited by the use of inappropriate and inaccurate scales of human-machine trust. An attempt is made here to validate a scale proposed by Jian, Bisantz, and Drury (2000) that measures trust and distrust in automated systems. Sixty participants completed a patient monitoring task with the aid of an imperfect signaling system. Confirmatory factor analyses were conducted using LISREL 8.0 to determine the best fitting measurement model. Chi-square difference tests indicated that the best fitting model was the 2-factor oblique model. These results suggest that when using the System Trust Scale, researchers should treat trust as a multi-dimensional construct comprising of two distinct, yet related, factors. Implications for future research and measurement development are discussed.

Current Trends in Adaptive Training With Military Applications: An Introduction

The U.S. militarys operational and institutional training requirements continue to increase in scope and complexity; but training resources, including time, manpower, and money, are limited. Many of the solutions the military has proposed to meet these challenges depend heavily on adaptive training. The purpose of this special issue is to examine current trends in adaptive training, with a particular attention to the military environment. This article summarizes contemporary approaches and challenges to implementing adaptive training and provides an overview of the articles included in the special issue.

Measurement Invariance of the Nasa TLX

Mental workload is one of the most important constructs of interests for Human Factors researchers. Adequately assessing the amount of mental workload that people experience while performing tasks under specific conditions is essential for the design of safe and efficient systems. Due to its ease of use, the NASA TLX has become the most widely used method of measuring mental workload. However, its psychometric properties are still questionable. The purpose of this study was to examine the extent of measurement invariance of the TLX and raise awareness in the Human Factors community. Two hundred participants reported the amount of mental workload they typically experience while driving in urban and rural areas and across the country. Results indicated that the TLX lacked scalar invariance, thereby biasing the estimation of mean scores and making the examination of mean differences misleading. These findings suggest that researchers should first examine the extent of measurement invariance of the TLX before they proceed to make inferences about mean differences in the amount of mental workload reported by participants under different conditions.

The effect of sonification display pulse rate and reliability on operator trust and perceived workload during a simulated patient monitoring task

The present study investigated the effects of sonification pulse rate and sensor reliability on operator trust and mental workload. Processing resources and operator trust were sensitive to both pulse rate and sensor reliability. These findings suggest that setting pulse rates to 60 pulses per min may have considerable benefits in critical task environments.

The effect of sonification pulse rate on perceived urgency and response behaviors

Emergency signal researchers have devoted considerable energy to understanding the perceived urgency and performance effects of reliable and marginally reliable discrete auditory signals. Relatively little attention has been paid to aspects of continuous auditory displays. The purpose of the current study was to demonstrate and document the effects of sonification presentation rate on perceived urgency and response behaviors during a simulated patient monitoring task. As expected, participants rated shorter interpulse intervals as being significantly more urgent than longer pulse intervals. Participants also responded faster to patient problems when interacting with a sonification system that used shorter pulse intervals.

Examining Predictors of Visual Search Success in Transportation Security Officers and Behavior Detection Officers

Transportation Security Officers (TSOs) and Behavior Detection Officers (BDOs) are an integral part of the Transportation Security Administration’s (TSA) multilayered security program. Both officers are required to visually search their environments for prohibited items and cues that might be indicative of a threat. The purpose of this project was to identify factors that predicted the visual search success of these officers. A simulated visual search task was completed by 375 TSOs and BDOs, along with a battery of surveys designed to measure individual differences in personality traits, abilities, hobbies, and spatial ability. Results showed that TSOs and BDOs were highly accurate in their searches but that TSOs searched images faster than BDOs without sacrificing accuracy. Additional results showed that the strongest predictors of visual search accuracy were search speed and search consistency, but spatial ability emerged as a significant predictor for TSOs and frequency of video-game play emerged as a significant predictor for BDOs. Additional traits were also correlated with search performance but did not emerge as significant predictors in our regression models. Practical implication and directions for future research are discussed.

An Examination of Visual Search Success for Transportation Security Officers and Behavior Detection Officers

This paper discusses ongoing research that seeks to better understand the core visual search skills and requirements of Transportation Security Officers (TSOs) and Behavior Detection Officers (BDOs). The purpose of the first phase of research is to compare TSO and BDO visual search performance on a simple visual search task and to determine whether certain personality and demographic characteristics are related to search performance. The goal of the second phase of research is to identify measures and assessment devices that are more applicable to the visual search requirements of the BDO position. Methods and approaches used to answer key questions related to each phase of research are described, as are potential implications of the research.

The Effects of Relative System Reliability and Prioritization on Alarm Reaction Patterns

Alarm system operators often manage multiple alarm systems concurrently. Because such situations often accompany cascading events, it is important to know how operators sequence responses. We examined how the relative reliability and priority of two concurrent alarms affected alarm gauge reset patterns. We hypothesized that operators would respond first to an alarm with higher reliability or higher priority when the other variable was held constant. We also expected participants to respond to alarms with higher priority first when they occurred at the same time as a high-reliability alarm. Sixty-one Old Dominion University undergraduates performed a tracking task and responded to gauge fluctuations (alarms). A between subjects ANOVA revealed that participants responded to alarms with higher priority first when reliability was constant, and to higher reliability alarms first when priority was constant. Our results suggest that relative priority and reliability may be useful parameters to control in complex task situations.

The Effects of Automation Expertise and System Confidence on Trust Behaviors

Trust in automation is more likely to be appropriate when information about the automations capability is available. The goal of this study was to determine how automation expertise and system confidence affected automation trust behaviors. Forty-one participants completed a target detection task while receiving advice from an imperfect diagnostic aid that varied in expertise (expert vs. novice) and confidence (75% vs. 50% vs. 25%, no aid). Results showed that participants were more willing to comply with the highly confident expert aid than the highly confident novice aid. Furthermore, participants were more apt to generate false alarms as system confidence increased. These results suggest that, similar to interpersonal relationships, humans appraise automation features such as confidence and expertise when deciding to comply with automation. Implications and direction for future research are discussed.