System reliability, performance and trust in adaptable automation.

The present study examined the effects of reduced system reliability on operator performance and automation management in an adaptable automation environment. 39 operators were randomly assigned to one of three experimental groups: low (60%), medium (80%), and high (100%) reliability of automation support. The support system provided five incremental levels of automation which operators could freely select according to their needs. After 3 h of training on a simulated process control task (AutoCAMS) in which the automation worked infallibly, operator performance and automation management were measured during a 2.5-h testing session. Trust and workload were also assessed through questionnaires. Results showed that although reduced system reliability resulted in lower levels of trust towards automation, there were no corresponding differences in the operators' reliance on automation. While operators showed overall a noteworthy ability to cope with automation failure, there were, however, decrements in diagnostic speed and prospective memory with lower reliability.

Effects of extended lay-off periods on performance and operator trust under adaptable automation.

Little is known about the long-term effects of system reliability when operators do not use a system during an extended lay-off period. To examine threats to skill maintenance, 28 participants operated twice a simulation of a complex process control system for 2.5 h, with an 8-month retention interval between sessions. Operators were provided with an adaptable support system, which operated at one of the following reliability levels: 60%, 80% or 100%. Results showed that performance, workload, and trust remained stable at the second testing session, but operators lost self-confidence in their system management abilities. Finally, the effects of system reliability observed at the first testing session were largely found again at the second session. The findings overall suggest that adaptable automation may be a promising means to support operators in maintaining their performance at the second testing session.

High-performance, single-layer antireflective optical coatings comprising mesoporous silica nanoparticles.

Mesoporous silica nanoparticles are used to fabricate antireflectance coatings on glass substrates. The combination of mesoporous silica nanoparticles in conjunction with a suitable binder material allows mechanically robust single layer coatings with a reflectance <0.1% to be produced by simple wet processing techniques. Further advantages of these films is that their structure results in broadband antireflective properties with a reflection minimum that can tuned between 400 nm and 1900 nm. The ratio of binder material to mesoporous nanoparticles allows control of the refractive index. In this report, we discuss how control of the structural properties of the coatings allows optimization of the optical properties.

Explicit control of adaptive automation under different levels of environmental stress.

This article examines the effectiveness of three different forms of explicit control of adaptive automation under low- and high-stress conditions, operationalised by different levels of noise. In total, 60 participants were assigned to one of three types of automation design (free, prompted and forced choice). They were trained for 4 h on a highly automated simulation of a process control environment, called AutoCAMS. This was followed by a 4-h testing session under noise exposure and quiet conditions. Measures of performance, psychophysiology and subjective reactions were taken. The results showed that all three modes of explicit control of adaptive automation modes were able to attenuate the negative effects of noise. This was partly due to the fact that operators opted for higher levels of automation under noise. It also emerged that forced choice showed marginal advantages over the two other automation modes. Statement of Relevance: This work is relevant to the design of adaptive automation since it emphasises the need to consider the impact of work-related stressors during task completion. During the presence of stressors, different forms of operator support through automation may be required than under more favourable working conditions.

Assessment of structural knowledge as a training outcome in process control environments.

OBJECTIVE: The objective of the present studies was to apply a novel method for structural knowledge assessment to process control to assess the potential of its measures as a training outcome. BACKGROUND: Traditionally, knowledge is assessed by verbal achievement tests on the subject matter. However, traditional methods are regarded as limited in their ability to assess higher-order learning or understanding. METHOD: Two experiments (Experiment 1, N= 41; Experiment 2, N= 50) were conducted in which participants were given a 4-hr training session on a simulated process control task. At a later testing session, participants worked on the task for 70 min and completed knowledge tests on declarative, procedural, and structural knowledge. Structural knowledge was measured with the computer-based Association Structure Test (AST), which combines an association task and Pathfinder network on the basis of relatedness ratings. RESULTS: In both studies, structural knowledge was significantly related to diagnostic performance, and evidence was found for internal consistency as well as convergent and predictive validity. CONCLUSION: Findings indicate that structural assessment with the AST shows promise as a training outcome in process control. APPLICATION: Potential applications of this research include the improvement of training design, delivery, and evaluation.

The influence of user expertise and prototype fidelity in usability tests.

An empirical study examined the impact of user expertise and prototype fidelity on the outcomes of a usability test. User expertise (expert vs. novice) and prototype fidelity (paper prototype, 3D mock-up, and fully operational appliance) were manipulated as independent variables in a 2x3 between-subjects design. Employing a floor scrubber as a model product, 48 users carried out several cleaning tasks. Usability problems identified by participants were recorded. Furthermore, performance, system management strategies and perceived usability were measured. The results showed that experts reported more usability problems than novices but these were considered to be less severe than those reported by novices. Reduced fidelity prototypes were generally suitable to predict product usability of the real appliance. The implications for the running of usability tests are specific to the fidelity of the prototype.

The predictive qualities of operator characteristics for process control performance: the influence of personality and cognitive variables.

This article examines the relationship between operator characteristics and process control performance. Thirty-nine trainee operators participated in a 4-h training session of a simulated process control task and a testing session in which various system faults had to be managed. Cognitive ability, cognitive flexibility, self-efficacy and personality traits were measured as operator characteristics. Cognitive ability related positively to system control performance but not to diagnostic performance. Participants with low cognitive flexibility performed best on system control, whereas participants with high cognitive flexibility performed best on diagnostic performance. A hierarchical regression analysis revealed that cognitive ability, cognitive flexibility and declarative knowledge accounted for about 30% of the variability of system control. The findings suggest that consideration of cognitive ability and cognitive flexibility be increased in personnel selection for complex work environments.

The effects of heuristic rule training on operator performance in a simulated process control environment.

In complex work environments, the occurrence of novel system states represents a particular challenge for the design of training. This article is concerned with the use of heuristic rules to prepare operators for the management of unfamiliar fault states. An experiment was carried out to examine the effects of heuristic rule training on operator performance and system management behaviour. Thirty-nine trainee operators from the chemical industry took part in the study. They were trained for 4 h on a PC-based simulation of a process control task. Operators in the experimental group received training on heuristic rules while operators in the control group did not. One week later the operators participated in a 70-min testing session. While the results showed that heuristic rules training led to better diagnostic performance, it was also associated with increased operator fatigue and impaired secondary task performance. The implications of the findings for using heuristic rule training are discussed.

Adaptability of training in simulated process control: knowledge- versus rule-based guidance under task changes and environmental stress.

OBJECTIVE: The study examined the adaptability of different types of process control training across changes in task and environmental stress. BACKGROUND: The literature on training leads us to expect greater flexibility for system-based training, as opposed to procedure-based training. However, the stress literature suggests that knowledge-based strategies (making use of executive control) may be more vulnerable under stress conditions. METHOD: Two groups were given 6 hr of training on the Cabin Air Management System (CAMS), a complex, multilevel, PC-based process control task, emphasizing either system knowledge or use of procedures. They were then required to carry out the task for 3 hr (with noise during the middle 1 hr) across a range of both familiar and unfamiliar fault scenarios. RESULTS: For the primary control task, the system-trained group performed better, especially for less familiar and complex faults. However, for lower priority tasks requiring executive control, procedure-trained operators performed better and were less impaired by noise. CONCLUSION: System training was more effective for managing unexpected task events, whereas procedural training was better under noise. The results are interpreted in terms of the rationale for instructing operators in the range of strategies required for effective process skills in complex work environments. APPLICATION: Training methodologies for safety critical applications should aim to develop skill in the use of both procedural and system knowledge strategies. Operators should be trained in the most effective deployment of these strategies during unfamiliar task events and environmental stress and given stress exposure training.

Cognitive diversity and team performance in a complex multiple task environment.

This article examines the multiple effects of cognitive diversity in teams operating complex human-machine-systems. The study employed a PC-based multiple-task environment, called the Cabin Air Management System, which models a process control task in the operational context of a spacecraft's life support system. Two types of cognitive diversity were examined: system understanding and team specialization. System understanding referred to the depth of understanding team members were given during training (low-level procedure-oriented vs. high level knowledge-oriented training). Team specialization referred to the degree to which knowledge about system fault scenarios was distributed between team members (specialized vs. non-specialized). A total of 72 participants took part in the study. After having received 4.5 h of training on an individual basis, participants completed a 1-h experimental session, in which they worked in two-person teams on a series of fault scenarios of varying difficulty. Measures were taken of primary and secondary task performance, system intervention and information sampling strategies, system knowledge, subjective operator state, communication patterns and conflict. The results provided evidence for the benefits of cognitive diversity with regard to system understanding. This manifested itself in better primary task performance and more efficient manual system control. No advantages were found for cognitive diversity with regard to specialization. There was no effect of cognitive diversity on intra-team conflict, with conflict levels generally being very low. The article concludes with a discussion of the implications of the findings for the engineering of cognitive diversity in teams operating complex human-machine-systems.

Consumers' use of written product information.

Two studies were conducted to investigate the predictive role of person-specific, product-specific, and situation-specific influences on the use of instruction manuals in the field of electrical consumer products. In a laboratory study, 42 participants were observed while putting a vacuum cleaner into operation. Situational primes (i.e., receiving a verbal cue that the packaging contains an instruction manual) increased the probability of the user manual being read. Additional verbal information that the manual contains information on energy-saving behaviours was especially motivating for persons with high environmental concern. Self-report data, collected on a wide range of products, suggest that product complexity is the best predictor of instruction manual use. In a second study with 30 participants, different positions of product labels were compared, i.e. placing the information on the packaging or directly onto the product. Information placed directly onto the product had a significantly higher influence on participants' actual behaviour than providing the same information on the packaging.

Environmental conservation in the domestic domain: the influence of technical design features and person-based factors.

This article presents three experiments that examined proenvironmental behaviour during utilisation of electrical consumer products in the domestic domain. One experiment was carried out in the laboratory (N=48), two others in the field (N=18, N=24). First, the work aimed to evaluate various ergonomic measures with regard to their effectiveness to influence proenvironmental behaviour. Second, it examined the relation of person-based factors (e.g., environmental concern) and behaviour. Third, it examined the generalizability of findings from the laboratory to a field setting. The results suggested that design modifications of kettle (e.g., kettle size, integrated user support) are effective in improving proenvironmental behaviour (i.e., resource consumption). Relationships between person-based factors and behaviour have been found, though they were not consistent because the nature of the relationship may be modified by design features (e.g., integrated user support). There was general confirmation of the results from the lab-based experiment by field research, suggesting the suitability of laboratory work to research environmental issues in the domestic domain.

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.

Performance in a complex multiple-task environment during a laboratory-based simulation of occasional night work.

A study was carried out to examine the impact of occasional night work on simulated process control using a complex task environment. The 21 student participants were tested during 2 6-hr simulated shifts (daytime and night). In addition to the primary system management task, the simulation allowed measurement of fault diagnosis behavior, monitoring and control actions, and two secondary tasks--alarm reaction time and system status checks (prospective memory)--as well as subjective state. Consistent with predictions from compensatory control theory, night work did not impair system performance, although monitoring and control were reduced (supported by subjective reports of increased use of risky "corner-cutting" strategies). Secondary tasks showed an increase in alarm reaction time during night work, but there was no effect on prospective memory and no clear pattern of change in subjective state. Actual or potential applications of this research include the design of complex systems for nighttime operation.

Improving ecological performance of electrical consumer products: the role of design-based measures and user variables.

This research is concerned with the ecological performance of electrical consumer products. It examines the influence of design-based measures on various ecological performance parameters and the relationship of user variables and performance. In the experimental scenario, 40 users were asked to clean a room with a vacuum cleaner under different conditions. In a multi-factorial design, the following independent variables were employed: on-product information, enhanced display-control labelling and proximity of controls. Measures of user variables (environmental concern, knowledge, habits) of ecological behaviour were also taken. The results showed that enhanced display-control labelling improved ecological performance but only when the label was placed close to the user. On-product information only resulted in behavioural change when it was in close spatial proximity to the control device. A positive effect on ecological performance was also observed when controls were in a proximal rather than distal position. Among user variables, habits were found to have an influence on behaviour shown in experimental scenarios. A practical implication of the findings for environmentally friendly design of consumer products is that there should be a stronger focus on system-based measures rather than information-based measures. Finally, the article discusses the theoretical implications of using operational scenarios rather than the information display board paradigm.

Influence of Bridgehead Substitution and Ring Annelation on the Photophysical Properties of Polycyclic DBO-Type Azoalkanes.

The photophysical data for the polycyclic, bridgehead-substituted derivatives 1-10 of the photoreluctant diazabicyclo[2.2.2]oct-2-ene (DBO) are presented. Substitution on the bridgehead positions with radical-stabilizing substituents enhances the photoreactivity (Phi(r)) and decreases the fluorescence quantum yields (Phi(f)) and lifetimes (tau) compared to the parent DBO. The annelated rings have no influence on the photoreactivity, except when steric interactions with an alpha substituent hinder the optimal radical-stabilizing conformation. The fused rings and some of the bridgehead substituents reduce the solvent-induced quenching of the singlet-excited azo chromophore by steric shielding of the azo group and, thus, increase the fluorescence quantum yields and lifetimes.