Secondary Task Performance Research Articles

The effects of level of automation and adaptive automation on human performance, situation awareness and workload in a dynamic control task

This paper extends previous research on two approaches to human-centred automation: (1) intermediate levels of automation (LOAs) for maintaining operator involvement in complex systems control and facilitating situation awareness; and (2) adaptive automation (AA) for managing operator workload through dynamic control allocations between the human and machine over time. Some empirical research has been conducted to examine LOA and AA independently, with the objective of detailing a theory of human-centred automation. Unfortunately, no previous work has studied the interaction of these two approaches, nor has any research attempted to systematically determine which LOAs should be used in adaptive systems and how certain types of dynamic function allocations should be scheduled over time. The present research briefly reviews the theory of human-centred automation and LOA and AA approaches. Building on this background, an initial study was presented that attempts to address the conjuncture of these two approaches to human-centred automation. An experiment was conducted in which a dual-task scenario was used to assess the performance, SA and workload effects of low, intermediate and high LOAs, which were dynamically allocated (as part of an AA strategy) during manual system control for various cycle times comprising 20, 40 and 60% of task time. The LOA and automation allocation cycle time (AACT) combinations were compared to completely manual control and fully automated control of a dynamic control task performed in conjunction with an embedded secondary monitoring task. Results revealed LOA to be the driving factor in determining primary task performance and SA. Low-level automation produced superior performance and intermediate LOAs facilitated higher SA, but this was not associated with improved performance or reduced workload. The AACT was the driving factor in perceptions of primary task workload and secondary task performance. When a greater percentage of primary task time was automated, operator perceptual resources were freed-up and monitoring performance on the secondary task improved. Longer automation cycle times than have previously been studied may have benefits for overall human–machine system performance. The combined effect of LOA and AA on all measures did not appear to be ‘additive’ in nature. That is, the LOA producing the best performance (low level automation) did not do so at the AACT, which produced superior performance (maximum cycle time). In general, the results are supportive of intermediate LOAs and AA as approaches to human-centred automation, but each appears to provide different benefits to human–machine system performance. This work provides additional information for a developing theory of human-centred automation.

Assessment of Cognitive Load in Multimedia Learning with Dual-Task Methodology: Auditory Load and Modality Effects

Using cognitive load theory and cognitivetheory of multimedia learning as a framework,we conducted two within-subject experimentswith 10 participants each in order toinvestigate (1) if the audiovisual presentationof verbal and pictorial learning materialswould lead to a higher demand on phonologicalcognitive capacities than the visual-onlypresentation of the same material, and (2) ifadding seductive background music to anaudiovisual information presentation wouldincrease the phonological cognitive load. Weemployed the dual-task methodology in order toachieve a direct measurement of cognitive loadin the phonological system. In bothexperiments, the modality effect could beconfirmed in the patterns of secondary taskperformance and in the primary learning task.

Cognitive demands of collision avoidance in simulated ship control.

The study examines the cognitive demands of collision avoidance under a range of maritime scenarios. Operators used a PC-based radar simulator to navigate set courses over 100 6-min trials varying in collision threat and traffic density. Corrective maneuvers were made through the application of standard navigation rules and by using two decision aids (target acquisition and test maneuver). Results showed widespread effects of collision threat in terms of decision aid use, subjective workload, and secondary task performance. Most notably, demand increased markedly over the course of emergency trials, in which collision threat resulted from rule violation by target vessels. The findings are discussed in terms of the comparison between predictable demands (requiring standard course changes) and those involving uncertainty about the others' intentions (involving more intensive monitoring and forced delays in corrective action). The study has relevance for the design of collision avoidance systems, specifically for the use of ecological displays.

Does articulation contribute to modifications of postural control during dual-task paradigms?

Many studies have been carried out to investigate the attentional resources required for postural control, using a ‘dual-task’ methodology in which performance on mental and postural control tasks is compared when these are carried out separately and concurrently. Most mental tasks used in these dual-task studies have employed verbal responses. However, changes in respiration during speech production are known to produce changes in postural control. Hence, the goal of this study was to determine whether articulation might contribute to the changes found in postural sway when a spoken mental task is being performed and to determine if the type of postural control measurement might also have an impact on the outcome of the study. Twenty young healthy participants were asked to stand on a force platform while executing secondary tasks that were performed silently or required a verbal response, and that required high or low levels of attention. Vision and postural task difficulty were manipulated. Performance of all tasks produced an increased sway frequency and decreased sway amplitude relative to the no task baseline. However, tasks that required articulation resulted in a more pronounced increase in postural sway frequency and sway path than did the tasks that did not require any articulation. These findings could imply that the addition of a secondary task results in increased stiffness, whereas articulation results in a further increased frequency of sway, which leads to an increase in sway path. We conclude that changes in the various parameters of sway that accompany performance of secondary tasks are complex, and are not always wholly attributable to attentional load, but may also be partly due to the motor requirements of the task, such as those involved in articulation.

CAMS as a tool for human factors research in spaceflight

The paper reviews a number of research studies that were carried out with a PC-based task environment called Cabin Air Management System (CAMS) simulating the operation of a spacecraft's life support system. As CAMS was a multiple task environment, it allowed the measurement of performance at different levels. Four task components of different priority were embedded in the task environment: diagnosis and repair of system faults, maintaining atmospheric parameters in a safe state, acknowledgement of system alarms (reaction time), and keeping a record of critical system resources (prospective memory). Furthermore, the task environment permitted the examination of different task management strategies and changes in crew member state (fatigue, anxiety, mental effort). A major goal of the research programme was to examine how crew members adapted to various forms of sub-optimal working conditions, such as isolation and confinement, sleep deprivation and noise. None of the studies provided evidence for decrements in primary task performance. However, the results showed a number of adaptive responses of crew members to adjust to the different sub-optimal working conditions. There was evidence for adjustments in information sampling strategies (usually reductions in sampling frequency) as a result of unfavourable working conditions. The results also showed selected decrements in secondary task performance. Prospective memory seemed to be somewhat more vulnerable to sub-optimal working conditions than performance on the reaction time task. Finally, suggestions are made for future research with the CAMS environment.

Expertise, attention, and memory in sensorimotor skill execution: impact of novel task constraints on dual-task performance and episodic memory.

Two experiments explored the attention and memory processes governing sensorimotor skill. Experiment 1 compared novice and experienced golf putting performance in single-task (putting in isolation) and dual-task conditions (putting while performing an auditory word search task). At specific intervals, participants also produced episodic descriptions of specific putts. Experiment 2 assessed novice performance following training on the same putting task. In Experiment 1, experienced golfers did not differ in putting accuracy from single-to dual-task conditions and, compared to novices, had higher recognition memory for words heard while putting but diminished episodic memories of specific putts. However, when using an s-shaped arbitrarily weighted "funny putter" designed to disrupt the mechanics of skill execution, experienced golfers produced extensive episodic memories of specific putts but showed decreased dual-task putting accuracy and recognition memory for secondary task words. Trained novices produced results intermediate between the untrained novices and experienced golfers. As predicted by current theories of practice-based automaticity, expertise leads to proceduralized control that does not require constant attention. Resources are free to devote to secondary task demands, yet episodic memory for primary task performance is impoverished. Novel task constraints (e.g., a funny putter) increase attention to execution, compromising secondary task performance but enhancing memory for skill execution.

The Effects of Voice Technology on Test Track Driving Performance: Implications for Driver Distraction

Twenty-one subjects completed two sets of (8) laps around a 7.5-mile test track during two 4-hour sessions. They drove an instrumented vehicle while performing a combination of car following, peripheral target detection, and secondary (in-vehicle) tasks of varying complexity. Subjects performed one set of laps with each of two interfaces, voice-based and visual/manual. Secondary tasks comprised three categories including baseline tasks (radio tuning, phone dialing), simple tasks (message retrieval plus voice memo creation), and complex tasks (simple task components plus phone dialing and information retrieval from automated phone systems). Measures of driving performance, target-detection, secondary task performance and eye movements were recorded. Analyses were conducted to determine whether the voice-based interface reduced the relative distraction potential for secondary tasks of varying complexity. Generally, differences between tasks were stronger than differences between interface conditions. Measures of car-following performance, target detection, and secondary task performance revealed differences attributable to task complexity. Differences between the two interfaces were observed on peripheral target detection measures and on several driving performance measures. Overall, the benefits of using the voice-based interface were not large enough to appreciably reduce the distraction potential associated with performing the secondary tasks in the car-following scenario.

Psycho‐physiological analysis of mental workload at an elevated work place

Abstract:The purpose of the present study was to make a psycho‐physiological analysis in order to study the degree of mental workload at an elevated place. Two experiments were carried out on 10 scaffolding workers and 10 office workers (seven in Experiment 2), who were made to walk along the footing boards of a temporary scaffold. In Experiment 1, the psycho‐physiological responses of the subjects were measured. In experiment 2, the subjects’ spare capacity at an elevated place was measured using a dual task method. The results did not indicate any clear physiological response due to height elevation, although an increase in mental workload caused by the height was observed and secondary task performance fell at an elevated place in the office workers. The effect of the height was less noticeable on the scaffolding workers than on the office workers, but their spare capacity at that height decreased as the task demand increased due to narrower footing boards or increased task difficulty.

Individual differences during driver secondary task performance: verbal protocol and visual allocation findings

This paper reports a study in which visual allocation and verbal reports were recorded to determine individual differences in drivers conducting in-vehicle tasks. Participants drove a simulated route whilst conducting pre-defined tasks using the in-vehicle entertainment system. Tasks of varying complexity were presented to the participants. Licensed (experienced) drivers made significantly more verbal reports relating to road signs and markings, vehicles, scenery in general and vehicle operations; than did unlicensed (novices). No significant difference was found between expert and novice drivers when reporting in-car entertainment system related utterances. Surprising gender differences were also found. Males drover faster, with greater variance, and made more utterances in identified categories. Females were found to make significantly less verbal reports during secondary task performance. The difference in results obtained between expert and novices may imply that novices need to use their attention capacity to focus on the skill of driving, whereas experts through experience, have automated this skill and can use their attention capacity to more effectively during primary tasks. Results suggest that expert drivers are not necessarily experts at undertaking secondary tasks.

Effects of display design on performance in a simulated ship navigation environment

Although automation is playing an increasing role on the ship's bridge, empirical research on the effectiveness of alternative bridge designs is limited. In this paper, we describe an experimental study of the benefits of integrated information display, using a computerized simulation of a highly automated ship's bridge. The study compared three types of interface design, which presented radar and electronic chart information to the operator in different ways: (a) integrated display, (b) functionally-separate display, and (c) spatially-separate display. Effects were examined in relation to time on watch and scenario complexity. Following extensive training on the task, 39 participants were tested over a 4-h experimental session, during which they encountered a sequence of collision scenarios of varying complexity. Using a dual-task methodology, a range of measures of primary and secondary task performance were taken, together with assessment of information sampling behaviour and subjective operator state (workload, fatigue, anxiety and situation awareness). The results indicated slight navigational advantages of the integrated display over the two alternative display types, although it also incurred higher levels of operator cost, particularly fatigue. There were no marked effects of time on watch, but more complex scenarios were associated with impaired performance, increased workload and reduced situation awareness. Overall, the findings have suggested some benefits of integrating primary information sources in a ship's bridge environment. The study further confirms the value of experimental simulations as tools for investigating design issues for ship's bridge automation.

Development of a Test Protocol to Demonstrate the Effects of Secondary Tasks on Closed-Course Driving Performance

To assess the relative distraction potential associated with a variety of in-vehicle tasks, we developed a test protocol that provides an objective basis for demonstrating the tradeoffs between primary and secondary task performance in driving. The protocol includes two summary scores, one representing driving performance and one representing secondary-task performance. Driving performance was evaluated on a 1.3-mile test course, which included straight and curved road segments, a signalized intersection, a simulated work zone, two changeable-message signs, and six unexpected events. Secondary tasks included mental arithmetic, reading, writing, phone dialing, CD changing, route-guidance destination entry, eating, drinking and grooming. Twelve subjects drove an instrumented vehicle for 9 or 10 timed laps of the test course, each while performing a different secondary task or none (baseline). On average, we found a 15% decrement in driving performance scores on laps in which subjects engaged in a secondary task. Driving performance decrements were observed on 88% of these trials. Differences were observed between different secondary tasks. The pilot test results demonstrate the potential usefulness of the test protocol for assessing tradeoffs between primary and secondary tasks in driving.

Controlling for Individual Differences in a Dual-Task Setting: Equating the Baselines of Single Task Performance

Individual differences in human performance is an issue that confounds many studies and has not been properly controlled in the ergonomics/human factors literature. This paper examines the concept of individual differences in performance primarily from the perspective of cognitive performance. A study was designed to test the effect of a secondary visual task on a primary visual task. In one condition, participants performed the dual task, while assigning no weight to the secondary task. In the second condition, the primary task was performed simultaneously with the secondary task. The effect of the added workload was measured via the effect on primary task performance. In the baseline portion of the task participants had their baseline (80–90% accuracy) of performance collected by adjusting the stimulus duration. The individual participant stimulus duration was then used as the experimental stimulus duration and the effect of secondary task performance on primary task performance was measured.

Field dependence–independence from a working memory perspective: A dual-task investigation of the Hidden Figures Test

Field dependence-independence (FDI) is a construct intensively investigated within cognitive style research, but its cognitive underpinnings are not clearly specified. We propose that performance on FDI tasks primarily reflects the operations of the visuospatial and executive components of working memory. We tested this hypothesis in a dual-task experiment with a commonly used measure of FDI, the Hidden Figures Test. The results showed that performance on this test was impaired by concurrent performance of secondary tasks that primarily tap the visuospatial component (spatial tapping) and the executive component (2-back and random number generation), but was almost unaffected by other secondary tasks (simple tapping and articulatory suppression). Moreover, an analysis of secondary task performance ruled out the possibility of strategic trade-offs and revealed an intriguing dissociation for two different sets of “randomness” indices for the random number generation task. These results support the hypothesised mapping between FDI and working memory components and suggest that the dual-task paradigm can provide a useful way to bring underspecified constructs like FDI into closer alignment with theoretical ideas developed within cognitive psychology.

Effects of training on short- and long-term skill retention in a complex multiple-task environment

The paper reports the results of an experiment on the performance and retention of a complex task. This was a computer-based simulation of the essential elements of a spacecraft's life support system. It allowed the authors to take a range of measures, including primary and secondary task performance, system intervention and information sampling strategies, mental model structure, and subjective operator state. The study compared the effectiveness of two methods of training, based on low level (procedure-based) and high level (system-based) understanding. Twenty-five participants were trained extensively on the task, then given a 1-h testing session. A second testing session was carried out 8 months after the first (with no intervening practice) with 17 of the original participants. While training had little effect on control performance, there were considerable effects on system management strategies, as well as in structure of operator's mental model. In the second testing session, the anticipated general performance decrement did not occur, though for complex faults there was an increase in selectivity towards the primary control task. The relevance of the findings for training and skill retention in real work environments is discussed in the context of a model of compensatory control.

Effects of a reaction time task on postural control in humans

The purpose of the present experiments was to investigate the effects of a reaction time (RT) task on postural control, during and following the execution. Three different RT tasks consisting in verbal responses to visual and auditory stimuli were supposed to require different demands on cognitive resources. There was also a control condition in which no concurrent task was required. Postural control was assessed using a force platform. Results showed that (1) center of foot pressure (COP) displacements significantly decreased while concurrently performing the RT tasks, (2) this effect lasted for at least 10 s following the secondary task performance and (3) COP displacements decreased similarly, whatever the attentional requirements of the secondary task.

Workload and Reliability of Predictor Displays in Aircraft Traffic Avoidance

In 2 experiments we describe the relevance of aircraft predictor information to the availability and deployment of visual attention. In both, airplane pilots fly a simulator in which flight path prediction is given bearing on the future state of their own aircraft and of a second traffic "intruder" aircraft that they must maneuver to avoid. The cockpit traffic display on which this information is depicted is an integral component of the concept of free flight or pilot self-separation. In Experiment 1 we show that added layers of predictive information improve performance, reduce mental workload (as subjectively measured), and that added complexity of the visual display thus resulting does not increase the inferred measure of head downtime (secondary-task performance). In Experiment 2 we examine the consequences to performance and visual attention if prediction is occasionally in error. We adopt the hypothesis that trust is related to the relative allocation of attention between the predictor symbol and the raw data of actual aircraft state. Such unreliability damages performance to some extent, particularly when the unreliable predictor forecasts more complex conflict geometry. This cost reveals the substantial allocation of attention to the predictor symbol. However, pilots, knowing the level of unreliability, appear to be relatively well calibrated in their allocation of attention between the 2 information sources.

Multiple-task performance on a computer-simulated life support system during a space mission simulation

This paper presents an experiment which examined the effects of isolation and confinement during a simulation of a short-term space mission. During the 7-day spaceflight simulation, four Canadian astronauts were tested daily on a 30-min performance task. The task, CAMS (Cabin Air Management System), represents a computer-based simulation of a generic life support system. As a multiple-task environment, it allows the measurement of a wide range of task management variables such as primary and secondary task performance, and system control activities. Measures of subjective state variables were also taken. The results did not show any evidence of serious performance decrements for any crew member. The analysis revealed different adjustment patterns with which crew members responded as a function of mission duration and variations in workload. Among the secondary tasks employed, prospective memory was found to be more sensitive than reaction time to increases in workload. The paper concludes with a discussion of the utility of spaceflight simulations and computer-based simulations of space work.

The Effects of Divided Attention During Encoding and Retrieval on Amnesic Patients' Memory Performance

This study examined the effect of divided attention during encoding or retrieval on primary (recall) or secondary (button-pressing) task performance by amnesic patients and control subjects. Experiment 1 demonstrated that control subjects' recall was affected by divided attention during encoding but not during retrieval, while the amnesic patients' recall remained at the same low level for all conditions. Both groups showed a reduction in rate of button-pressing during encoding relative to their baseline levels and a further reduction during the retrieval interval. In Experiment 2, five learning trials, instead of just one, were presented. This acted to increase all subjects' recall and also had the effect of producing superior recall following free encoding relative to encoding during divided attention for the amnesic patientsas well as for the control subjects. Button-pressing performance during the encoding interval increased to baseline for both groups during the five presentation trials, but there was no increase in the rate of button-pressing during the retrieval interval. Amnesic patients' normal attention to the primary task during encoding and retrieval was felt to have several implications for future neuroimaging tasks with these patients.

Expertise and Age Effects on Pilot Mental Workload in a Simulated Aviation Task

This study investigated the effects of expertise and age on cognitive resources relevant to mental workload of pilots engaged in simulated aviation tasks. A secondary task workload assessment methodology was used, with a PC-based flying task as the primary task, and a Sternberg choice reaction time task as the secondary task. A mixed design using repeated measures was employed, with age and expertise as between-subjects factors and workload as the within-subjects factor. Pilots ranging in age from 21 to 79 years and 28 to 11,817 hours of flight time served as subjects. Of interest was whether expertise would mitigate the adverse effect of aging on pilots' mental workload handling ability as defined by two measures of secondary task performance: choice reaction time and accuracy. Results indicated that expertise did mitigate the effects of age regarding secondary task accuracy. Implications of results are discussed, and directions for future research are presented.

Detecting short periods of elevated workload: A comparison of nine workload assessment techniques.

The present experiment tested the merits of 9 common workload assessment techniques with relatively short periods of workload in a car-driving task. Twelve participants drove an instrumented car and performed a visually loading task and a mentally loading task for 10, 30, and 60 s. The results show that 10-s periods of visual and mental workload can be measured successfully with subjective ratings and secondary task performance. With respect to longer loading periods (30 and 60 s), steering frequency was found to be sensitive to visual workload, and skin conductance response (SCR) was sensitive to mental workload. The results lead to preliminary guidelines that will help applied researchers to determine which techniques are best suited for assessing visual and mental workload.