What is cognitive ergonomics?
Cognitive ergonomics is a division of ergonomics (or human factors): which helps to ensure ‘appropriate interaction between work, product and environment, and human needs, capabilities and limitations. In this human-system interaction, cognitive ergonomics focuses on mental processes, especially on cognitive functions and psychological/behavioural level interactions.
The goal is to elucidate the nature of human abilities and limitations in information processing. In cognitive ergonomics, these aspects are studied in the context of work and other systems. In recent years, there has also been a trend to exploit the methods of neuroscience also in the field of ergonomics. The term neuroergonomics is used when the focus is on neurological and physiological functions and biological explanations.
In ergonomics and psychology, cognition refers to the mental processes that are involved in processing and handling information, i.e. encoding, maintaining, rehearsing, recalling, and transforming information in the human mind and brain.
. Human cognition can be divided into several functions that underlie optimal human performance, which are as follows;
- Sensation and perception refers to perception of stimuli gathered through the senses such as sight, hearing, taste, smell, and/or touch.
- Attention is the stage where the processing is focused on certain aspects of perceived information or processing may be divided between two or several aspects. For example, in a control room one needs to notice if there has been a significant change in the situation.
- Working memory includes a short term memory storage in which information is available for up to 30 seconds. It also refers to the processes with which information is actively rehearsed and manipulated in the mind. For example, a telephone operator has to rehearse the name of the desired person until she/he has connected the call.
- Long term memory is a permanent store for different kinds of information. Semantic memory refers to the storage of knowledge about the world, symbols, and concepts. Episodic memory contains information about events and episodes, whereas events in an individual´s personal life are referred to as autobiographical memories.
Research on human cognition describes the nature of the human cognitive system. This knowledge of the human part of the system is needed in the design of equipment, appliances etc. It is useful in appreciating the critical aspects when one tries to fit an environment to the human cognitive functions that are relevant to the specific job or task.
Methods of cognitive science
Cognitive ergonomics not only utilizes the general knowledge originating from basic and applied studies, but also specific knowledge obtained when studying a specific task and situation. The core method being utilized in cognitive psychology is experimental and behavioural: the question of interest is studied in a controlled (laboratory) environment, by using carefully selected stimulus material, and by ensuring a balanced the order of the conditions that are being studied. Behavioural measures such as response times and percentage of correct responses provide information on a human´s ability to perform efficiently under various conditions. Brain imaging techniques can help to clarify the underlying biological and physiological aspects of cognition. Experimental neuropsychology aims to understand the principles of cognitive processing in both healthy and damaged systems. Simulating human cognition computationally and mathematically is also a method that can be applied in cognitive science.
The aim of the experimental research is to provide reliable results on the specific mechanisms explaining human cognition. One unfortunate effect of this careful experimental control, is that only a limited number of issues can be studied within a single experiment. Thus, there are hundreds of thousands of studies sometimes with apparently conflicting results on a myriad of issues. It is challenging to obtain a full perspective of the nature of human cognition and to apply this knowledge. Therefore reliable knowledge on cognition requires complimentary theories and replication of experimental results.
Studying cognition in everyday contexts
Two issues are crucial when results concerning the nature of human cognition are applied in the everyday context, e.g. in the field of ergonomics. First, ecological validity, which means that the results that are obtained also apply outside the laboratory. This requires that the methods, materials, and setting of the study approximate to the real-world task that is being examined. Second, the generalizability of the results, which refers to the concept that the results also can be applied to outside the specific context in which they were obtained. This requires meticulous control of experiments to ensure that they are based on truly generalizable principles of human cognition and performance. The optimal situation is that the study should utilize ecologically valid methods and produce generalizable results.
In addition to objective behavioural and physiological methods, also there are other methods that can shed light on cognitive performance. For example reliable questionnaires, can be used to study the frequency of cognitive failures or memory problems at work, or the work load experienced by the employee. Cognitive task analysis methods try to capture people’s thoughts, focus of attention, decision making strategies, and the basis for skilled performance.
There are various methods available for analysing cognitive tasks, e.g. knowledge elicitation and cognitive engineering. These techniques aim to understand what people know and how they know it. Cognitive task analyses collect data via interviews, self-reports, observations, and automated collections of behavioural data. They can focus on the present, on events that have happened, or on future prospects. The data can be gathered in real-world or in simulated, even virtual environments. The target can be either typical routine events or rare or challenging events. Data can be analysed and represented in a variety of ways. The goal is to gain an insightful account of the cognitive phenomenon underlying real-world tasks in complex and dynamic work settings. 
Cognition at work
Cognitive functions are subjected to their limits in the same way as the physical characteristics. Even the most adept juggler cannot throw ten apples into the air and catch them all with only two hands. However, the brain’s functional capacity limits are not visible and usually cannot be consciously recognized. Therefore, it is essential to apply reliable knowledge on these aspects of human characteristics in order that we can ensure that they are not overwhelmed at work. It is important to note that cognitive limitations will have a less significant impact on performance if the task at hand is learned to such a level that it becomes an automatized skill, since automatized processes do not burden the limited capacity of attention and working memory.
Perception and attention at work
Human beings have a limited ability to perceive the environment, and especially to perceive all the details. People do not notice everything that would be relevant in their work and they are easily distracted by co-workers.
There are also many working conditions, such as poor lighting, that may impair a worker´s ability to perceive objects and to focus attention on relevant aspects. Good visual perception requires that the symbols are clearly noticeable: i.e. the size of a text is large enough and that there is adequate contrast between the symbols and the background. Thus good lighting conditions will increase the visibility and the impact of size and contrast.
Good perception conditions make targets visible. Furthermore, they decrease the amount of time that is needed in visual search when a certain symbol is being sought from among other targets. Targets that pop out from the environment are found easier and faster than complex targets that require that the region is scanned serially. If one reduces the number of background objects or grouping targets instead of scattering them evenly then this will also help to direct attention to the relevant objects, e.g. on an operator’s desktop or in the vehicle’s control board. An efficient way to direct attention and to enhance perception is to provide an alert about an incoming relevant stimulus or its spatial location in the environment before the object appears.
It is important to note that there are several conditions that are distracting and direct attention towards irrelevant objects. For example, the ability to focus visual attention and to maintain information active in visuo-spatial working memory is easily distracted by moving objects and flashing lights.  In the auditory domain, a noise that includes detectable speech sounds may impair perception, attention, and other forms of processing of linguistic information.  Furthermore, the ability to hear and to follow a conversation is impaired in noisy conditions; this is a fact to be considered when designing communication and warning signals.
New technologies also utilize other sense modalities, such as touch. In principle, the incorporation of multimodal information can be an effective way to divide attention or to direct the focus of attention towards relevant objects. However, every sense modality has its limitations that need to be considered when designing work.  Best practices of cognitive ergonomics include:
- optimizing the size of symbols and text, contrast between objects and background, and lighting conditions.
- discernibility of targets, grouping of targets, small number of background objects, alerting about relevant stimulus.
- decreasing auditory and visual noise.
Working memory at work
While performing any task, it is crucial to effectively maintain and process all of the relevant information. Human beings have a limited ability to process information at the focus of attention, i.e. there are limits to the working memory system. The capacity of working memory is about 4 items and without rehearsal, information fades from the working memory in less than 30 seconds. 
Some of the capacity limitations of working memory can be avoided by decreasing the amount of noise and unnecessary visual information, and by limiting the information to be remembered. If the task or the system requires active maintenance and processing of codes or other details, it leads to unnecessary loading of working memory. In contrast, if there is no need to mentally rehearse trivial details, the capacity of working memory can be used for problem solving, decision making, and other crucial tasks. Therefore, good visualizations and other external memory aids can improve cognitive functioning and performance.
Whereas there is a general capacity to process information in working memory, the capacities of working memory and attention are also modality specific. Thus a system that allows the use of several modalities, e.g. visual and auditory instead of only the visual mode, helps to divide the attention and capacity requirements so that performance can be improved. Wicken’s  model is a practical way to realize the overlapping demands for information processing and to design work and systems that try to decrease the cognitive load by sharing the load between the non-overlapping resources.
Figure 1: Wicken’s (2008) model on overlapping demands for information processing defines four dichotomies of non-overlapping resources: 1) Modalities: auditory and visual perception use different resources, 2) Stages: perception/cognition and responding/action use different resources, 3) Codes: spatial and verbal/linguistic activity use different resources, 4) Visual processing: focal and peripheral vision use different resources.
Source:  copyright © 2008 by Human Factors and Ergonomics Society. Reprinted by Permission of SAGE Publications.
Working memory also is a site for executive functions, one can depict it as a kind of conductor of the orchestra of information processing in the human mind. Many tasks require that people switch their focus of attention or switch between different tasks or perform several tasks at the same time. These situations are cognitively demanding, and problems in the control of information processing may lead to action failures and lapses. For example, people may unintentionally press control switches on machines or they may accidentally throw away or dispose of some item that they will need later.
The costs of task switching have been convincingly demonstrated.  Performance, even in simple tasks, is prone to errors and there will be an increase in performance time if the individual must switch focus between tasks rather than finish one task before tackling the next. Underlying cognitive control processes are relevant to a wide variety of tasks that everyone encounters at work and in life in general. Therefore in designing work environments and tasks, it is crucial to strive to have situations that require neither constant switching between tasks nor performing several tasks at a time. Best practices of cognitive ergonomics include:
- reasonable number of objects/information to be kept in mind,
- decreasing unnecessary visual information, background speech, and interruptions,
- use of external memory aids and visualizations,
- non-overlapping modalities, codes, stages, and responses required in a task,
- reducing costs of task switching and the need to perform simultaneous tasks.
Memory and learning at work
The limitations of long-term memory are mainly related to the slow process of acquiring new knowledge and skills, the difficulties in recalling information and work procedures, and the rapid forgetting of information that has not been rehearsed. However, the capacity of long-term memory storage is unlimited, and at any age, there is ‘space’ to acquire new knowledge and skills.
According to recent reviews and meta-analyses, the most effective learning techniques are testing and distributed practice of the to-be-learned information/skill.  Distributed practice techniques consist of several practice phases instead of one massed practice. The literature of occupational training also considers the importance of evaluating what happens before the training as well as what happens after the training.
The human memory is reconstructive: information is not stored as a perfect recording, but retrieval of information from memory involves using the available information and cues about an event or the topic. The details are reconstructed on the basis of what is familiar, likely, and/or meaningful, or taking the context into consideration. The ability of human beings to define the source of recalled memories is limited. Therefore it is common to have false memories of actual details, even though the gist of the memory may be correct. Due to this reconstructive nature of memory, written and picture/video documentation is essential when detailed and exact recall is required. Best practices of cognitive ergonomics include:
- providing enough time for learning knowledge and skills,
- avoiding forgetting of relevant knowledge and skills by using them at work and by utilizing check lists and other aids,
- applying effective learning techniques at work if occupational training is the relevant solution,
- careful documentation of essential and detailed information and decisions.
Thinking and language processes at work
Thinking and communication are complex processes in natural settings. Laboratory studies have shown that human decision making, problem solving, and reasoning doesn’t follow normative rules, e.g. those of logical reasoning. Instead, people use rules of thumb that are not cognitively demanding but very often lead to acceptable solutions. However, many typical errors in decision making have been recognized in real life situations.
Several factors affect whether thinking and communication succeed at work and in complex problem solving tasks.  Thinking and communication rely on the basic cognitive processes described above. Furthermore, prior experience, knowledge, and skills affect how people evaluate the problems and try to solve them. Mental models are complex representations of situations and events, and they are used as a way to represent relevant information in thinking processes. Many workplace situations are complex and poorly defined. Thus it not may be immediately obvious how to solve a problem or whether a goal has been achieved, for example, how to improve safety attitudes and how large an intervention is needed in a particular case.
Thinking and communication at work often take place in teams and between individuals who have different expectations, roles, knowledge, experiences, educations, and job specific vocabularies.  In order that there will be effective communication, it is important that there should be some common ground, i.e. a degree of unified understanding among the team members. It is difficult to change the way people think, but there are some general rules that can help in debunking false assumptions, e.g. focusing on core facts rather than myths, and providing an alternative explanation for why some myth is wrong.  Best practices of cognitive ergonomics include:
- listing information and arguments relevant to the problem to be solved or the decision to be made,
- using graphics to represent relevant factors and their connections,
- constructing common understanding by making the content easy to
- debunking false assumptions.
Expertise at work
It takes time for an individual to develop into expert; it may require years of dedicated practice.  Experience and learning lead to superior performance in domain-specific tasks, i.e. tasks that require knowledge and skills relevant to that specific field or domain. The exceptional performance of experts when compared to novices is evident at multiple levels of cognition: finding and recognizing relevant stimuli, encoding and categorisation of material, the organisation of knowledge in long term memory, immediate recall, learning, and thinking. 
The superior skill of the expert is not only simply because he/she knows more than others, there also are qualitative differences in processing task-relevant information. Experts represent domain-specific knowledge and problems at an abstract level and concentrate on fundamental concepts, whereas novices focus more on superficial features and dominant objects. Experts are able to select information that is meaningful, that makes sense and is relevant to the task at hand. In problem solving, experts are able to think ahead, i.e. to use forward search to identify those possibilities leading to the best outcome.
Research on expertise has revealed the maximal adaptability of human cognitive skills. For a beginner, many tasks and situations at work are novel and they are thus cognitively more demanding than familiar or automatized tasks. In contrast, experts possess a vast amount of pre-learned knowledge and skills that can be used in deliberate and conscious ways to ensure exceptional performance. However, it seems to take 10 years or 10,000 hours of practice to develop such exceptional skills; this has been demonstrated in many different domains. Therefore, there has to be a trade-off between acquiring exceptional skills and the amount of training necessary to achieve adequate performance. When designing work and tasks, it is crucial to consider the level and kind of expertise required in the task, and the amount of training that is needed if novices of that domain are expected to perform these tasks. In many cases, it is more efficient that employees are able to apply their core expertise at work rather than undertaking many additional tasks that require other skills and understandings. Best practices of cognitive ergonomics include:
- utilizing the expertise of the employees,
- providing training for novices,
- finding a balance between tasks that require training and tasks that are based on a worker’s existing expertise.
Cognitive demands of work
There are certain conditions that make it even more demanding for a human to perform at an optimal level. The cognitive demands of the tasks and work environments in any job can be significant, e.g. working in changing conditions, doing multiple tasks at the same time, or being subjected to noise or interruptions at work. These conditions impair cognitive performance, and may thus develop into critical work-related factors that can lead to human errors and be responsible for health problems and/or accidents at work. Therefore in safety-critical domains, it is essential to consider human factors and utilize cognitive ergonomics to ensure performance and safety.
Specific work requirements
There are some jobs that overload performance capacity, endangering the safety and health of workers. The specific job demands can be physical, mental and/or psychosocial, e.g. the work of fire-fighters, police officers, medical specialists, pilots, and air traffic controllers.  High-demand jobs are often safety-critical, such as working in aviation, nuclear power, or health care, where the employees are responsible for other people’s safety and well-being.
The specific job demands may involve several factors, e.g. unconditional working hours and stress that are known to influence cognitive functioning. It is known that sleep deprivation related to shift work and working during normal sleeping hours exerts detrimental effects on cognitive performance. However, there are significant inter-individual differences in response to the sleep deprivation and night work. In addition, psychosocial stress may impair attention and memory function and increase the rate of errors and accidents at work.
Working in dynamic environments
Several working environments are complex and dynamic: the perceptual environment changes constantly, there are moving objects around, and performance requires rapid reactions and decision-making under pressures of time. Professional drivers, air traffic controllers, and firefighters are some of the employees required to have total and accurate situation awareness. They need to know what is going on and they have to understand what to do next in all circumstances.
According to Endslay’s (1995) model, situation awareness involves three levels:
- Perception refers to awareness of relevant objects, people, systems and other environmental factors.
- Comprehension is related to understanding the meaning of what was perceived: recognizing, interpreting and evaluating the significance.
- Projection refers to the ability to predict the situation in the near future, based on perceiving and understanding the dynamic elements of the environment.  Thus situation awareness is a complex phenomenon that depends on several basic and higher level cognitive processes.
Information technology and automation
Information and communications technology (ICT) has an increasing role at the work place: in Finland, nearly 75% of employees use a computer in their work and every third of them spends more than four hours of the working day in front of a computer. In service work, sales, and care work, the use of information technology has doubled during the last 10 years.  The aim of cognitive ergonomics is to ensure that also the information work with computers is effortless and that ICT improves a worker´s ability to perform a variety of tasks instead of causing unnecessary load, errors, and wasting of time.
Using computers does not necessarily decrease cognitive load. In fact, usability problems of information technology may disrupt performance. The increasing numbers of interfaces at work create new cognitive demands on employees: workers need to learn several kinds of applications and use diverse systems. Many tasks require also switching between several applications. If the applications do not have technical connections between them, work may involve moving information from one application to another, a task that a computer can do more efficiently than any human being.
The increase of information technology has also led to automation, e.g. in production, manufacturing, and traffic. Automation means that workers are responsible for monitoring and controlling the processes. As the complexity of systems increases, and they come to be operated by groups of people, it becomes more and more difficult to understand how the overall system works . There are examples from aviation, financial trading, and cloud computing that demonstrate accidents and errors that happen when technology fails, and people are not able to understand the system and to diagnose the problem. It is therefore necessary that technology provides people with the appropriate information, and workers learn and practice skills that make it possible to intervene should something go wrong. 
The nature of work in future
The nature of work has changed during the last decades, and the pace of change is likely to accelerate. The workforce is aging, work practices are changing, the transition to the provision of information and services requires new skills from employees, and new technologies affect how people work. Technology can impact on training methods and improve learning, and may offer new ways to modify the environment to make it more compatible with human abilities.
New enhancement technologies can even provide opportunities to improve an individual’s ability to learn and perform in cognitive tasks, even in old age and in extreme conditions.  Nonetheless, modulating the environment is the key method in ergonomics. Even if new technologies allow enhancement of individual’s abilities and skills, these technologies should not be considered as alternatives to improving poor work conditions; i.e. the well-being and health of employees has to be considered as a key component of work.
Conclusions: Towards optimal cognitive functioning at work
The aim of cognitive ergonomics is to design work conditions and environments that enhance cognitive functioning and human performance at work, and as a consequence improve productivity, safety, and health at work.
Human cognitive abilities and skills are limited but adaptive
Cognitive functions have their limits: in many cases, human beings have a limited capacity to perceive, focus and divide attention, learn, memorize, make decisions, solve problems, and communicate. On the other hand, the ability of humans to adapt in order to perform different tasks is exceptional. When designing work conditions one needs to make a trade-off between skills and limitations: people are able to overcome many cognitive limitations through learning, but this takes time.
It is easier to change work conditions than the human cognitive system
Today, there are few safe methods which can change the human cognitive system and the way people process information. However, there are numerous general principles and good practices of visual and cognitive ergonomics and the ergonomics of working hours, [organisational ergonomics], and [physical ergonomics] that help to avoid unnecessary cognitive load at work and that improve human performance. In practice, even if the focus of an intervention and design is on cognitive ergonomics, it is important to ensure that the solutions and proposals for changing a specific case also fulfil the requirements of physical and organisational ergonomics.
Better work for everyone
The individual differences and the wide spectrum of cognitive performance is evident in working life. Most conventional jobs employ people that do not come from selected populations, and no special cognitive capacity and skills are required, nor does working presume long training periods or high level of expertise. Furthermore, some workers may also have specific cognitive limitations, such as learning difficulties or other cognitive deficits. It is thus necessary to design work for all and to consider accessibility issues.
In the future, the greater amount of ageing workers will become a factor that may affect the diversity in work ability. Cognitive variables that are critical to performance in several occupations can begin to display age-related effects after 45 years of age, although individual variation is great. There are age-related reductions in visual function and hearing at least to some extent. Some mental processes which are critical for many jobs, i.e. working memory and executive functions, as well as dual task performance and task switching, appear to be most affected by age. Higher level cognitive functions also seem to decline with age, although practice and experience enhance performance in individuals of all ages.
It is accepted that older workers can adapt and compensate for a loss of capacity, and thus a high level of expertise may diminish the detrimental effects of age at least to some extent. Furthermore, there is no definitive evidence for the belief that work ability decreases with age. In addition, the between-individual and within-person variation in cognitive functioning increases with age. Therefore, chronological age is not an appropriate factor for assessing an individual’s cognitive performance and work ability, but instead there is a need for methods to estimate an individual’s functional age. These issues are especially relevant when deciding about the work abilities of ageing workers doing high-demand jobs.