Working in aviation requires operatives (pilots, controllers, airside safety, etc.) to take in information from a multitude of sources, assess this information, prioritise it, and use it to make decisions and take actions. This complete process from sensing information (whether it is aural, visual, mental, kinaesthetic, gustative or olfactory) through to taking action is referred to as “human information processing”, or information processing for short. So, information processing refers to the ability of the operator to process the type and amount of information within the required timeframe, and to do so in an effective manner that leads to suitable responses.
Need to Know
Information processing capabilities vary from person to person, day to day, place to place and task to task. It is particularly affected by age, health, stress, different environments, workplace cultures, experience levels, interpersonal relationships, distractions, and in particular, by its own limitations. These limitations can be substantial and will be explained later in this Article.
Knowing how our information processing capabilities can be limited is important in designing and delegating tasks to ensure that the information processing requirements fall within the capabilities of employees and colleagues (i.e. within their memory, attention and decision-making capabilities) such that the following are minimised:
- Failure to see information
- Misunderstanding information
- Handling the information incorrectly
- Forgetting the information.
- Reacting inappropriately
Perhaps more importantly, we should understand our own limitations, especially during periods of high workload and/or when particular illusions may go unnoticed.
Situational Awareness and Information Processing
Our situational awareness is built upon our perception of the world that relies on information attained through our senses. The information available to us includes: flight, navigation and engine instruments, primary flight displays, radar, TCAS, radio voice communications, data-link, direct vision, crewmember communication, vibrations, noises and smells, and more. It also includes our mental model of our “plan” of how things are expected to occur, and our prediction of what others’ plans are, and how they may progress. Our perception of the world will be a four-dimensional model. Four dimensions because we retain memory of what has occurred already and we are also able to project forward in time to predict what the situation will be. At any given moment, in three-dimensions, the accuracy of our situational awareness depends on how accurate our perception is compared to reality. It is possible to be highly accurate, especially in simple and familiar situations. However, our predictions for the future will be, on the whole, less accurate, as will our perception in complex and busy environments. We may have a good idea of what will happen when we ourselves make changes, corrections and decisions, and this will be based on our experience; however, it is less easy to judge what others will do. Therefore, maintaining situational awareness is a continuous process requiring mental effort and it will become vulnerable during periods of high workload where our information processing capacity is exceeded. And, usually, it is these high workload situations when we need to ensure that our situational awareness is as accurate as possible.
Building Blocks of Human Information Processing
It is accepted that there are at least four stages in information processing:
- motor action, or performing
Supporting these key steps in information processing are various elements of memory, referred to as sensory memory, working and short-term memory, long-term memory and motor memory. These are not distinct sections of the brain, but it is useful to refer to the functions that each provide as distinct from the others. Another important building block is the “attention directing” mechanism.
One major feedback loop exists, where we sense changes that occur due to our own actions – in this way we are able to measure and correct our progress in achieving a task i.e. digitally and analogue, e.g. by shooting more and more accurately towards a bull’s-eye, or by correcting continuously to maintain straight-and-level flight, respectively.
Another key feedback loop is when our mental model of the world, influenced by past experiences, drives our attention: we are looking for evidence that supports our model - even if it is wrong.
Vigilance and Attention
Vigilance in ATM refers to our state of awareness to external stimuli; this state can range from low to high levels of vigilance. Vigilance might best be described as a positively motivated intention to be ready to react to a range of inputs. It is an energetic state that we can turn-up and turn down at will, but also one which can drop off during periods of low stimulus, boredom, fatigue and stress. Our situational awareness will determine how vigilant we become and to what external data we include in our scan of awareness. For example, on a typical flight deck, pilots need to remain vigilant of a whole range of possible data, from engine, navigation, communication and other aircraft systems, as well as events occurring outside of the flight deck. It is just too much for our sensory and perception mechanisms to recognise and make sense of all this information. Which is why we need to “pay attention” to the most important stimulus in the moment, and divide our attention between various stimuli when there are several important factors that require our observation and response.
Attention is a necessary function if we are to focus on the things that matter at the right time. Various theories exist which explain the mechanism that permits multi-tasking, and also the degree to which we can or cannot multi-task. One determinant of whether we can multi-task or not is the capacity we have for dividing attention between stimuli. For the most intricate, or unfamiliar, tasks we usually require full attention and this will result in us being unable to perceive anything else that is occurring. E.g. whilst being occupied in a hobby such as delicate sculpture, we can become so engrossed that we fail to hear the phone ring, or notice someone entering the room. In the workplace this may also occur when we are fully occupied in dealing with many different inputs e.g. flying an unfamiliar non-precision approach in poor weather at night, we can fail to re-tune the navigation aids at the appropriate point. This is why some systems utilise visual and aural alarms to break our focus and “grab our attention”; it helps that we are particularly sensitive to hearing our own name and call-sign. It is also why pilots and air traffic controllers need to be persistent in maintaining scans, in which attention is temporarily broadened such that other critical information can be sensed. Having other team, and crew, members also allows attention to be divided between people which can greatly enhance the information processing capacity available; this requires effective planning and briefing.
As well as external events of relevance vying for our attention, our attention will always be tempted by loud, bright, moving and proximate events and objects; i.e. we are easily distracted by irrelevance, especially from tasks requiring applied thought - as anyone who has ever procrastinated will recognise. Also, distraction can be internally generated. Internal thoughts about current, past and future events will arise, and often these thoughts are totally unconnected with the task at hand. Internal distractions are more likely to occur when fatigued, stressed or ill.
Whether the input is sound, light, pressure, taste or smell, unless we can place our attention onto these inputs there is only a short period of time before the sensation disappears; e.g. visual memory lasts for less than 1 second, audible (echoic) memory lasts for up to 8 seconds. It is these "sensory memories" that allow us to immediately read-back a frequency, or recall a telephone number long enough to dial it once, but 30 seconds later be unable to recall accurately. Paying attention to any of these inputs will involve forming a perception and the transfer of data into more robust memory. This takes effort and involves the decision-making mechanism; in these examples this may be either continuously repeating the numbers (during which we can process no other information - at all) or writing down the information as a record.
Of course at this sensing stage we can be at a disadvantage if our sight and hearing are attenuated (naturally or not), and also if our inner ear is affected in any way. This means that our perception of the outside world will be incomplete, or distorted.
Perception is the process of converting sensory information into something that makes sense – i.e. creating an internal mental model of the outside world. Because we are unable to “collect” 100% of external data (as already mentioned above) our internal model will be incomplete. However, based on our previous experiences, we are often able to make sense of the little data we receive and create a realistic model based on our expectations. Much like the fact that we can easily recognise someone’s face from a badly pixilated picture; if it’s someone we know, then our brain literally fills in the gaps and joins the dots. It is this mechanism that helps us to divide attention and sometimes multi-task.
However, the same mechanism can lead us to “misperceive” the world – the more we rely on past experiences the more our expectations will distort our perception. For example, a helicopter pilot who regularly flies along snow-covered valleys in Norway will have a mental model of fir trees being 150ft tall. If he enters a valley which is full of newly planted fir trees he may fly much closer to the ground than intended as he has misperceived the scale of the outside world. Hence the importance of cross-checking our perceptions with other data; in this example – the radalt.
Another source of misperception concerns how juxtaposed objects within an environmental setting can influence each other to create a visual illusion.
Figure 1 above displays the exact same table but from different perspectives - even after measuring each table top and realising they are the same, it seems impossible for our brain to perceive anything but different tables.
Similarly in figure 2, although we can measure each horizontal line and recognise that they are the same length, it is impossible to shake off the perception that they are different.
Both these illusions have relevance for pilots judging the height, distance and slope of runways on approach.
Working Memory is the aspect of our memory that we use all the time when conducting any task. It holds small amounts of data for a very short time, which is to be used immediately. Therefore, we can read-back an Air Traffic Control instruction to descend and change Transponder Code and maintain these numbers long enough to enter them into the appropriate systems. Mental repetition may be required to achieve the task, but once completed the information is lost within 30 seconds and replaced with the next set of data we need e.g. setting-up the displays to facilitate an instrument approach.
Typically the capacity of our working memory is 7 digits +/-2. We can extend this by “chunking” digits together into meaningful blocks such as a long telephone number with 12 digits (e.g. 49 123 747 8989) can be chunked as shown into just 4 memorable blocks. Chunking can also be usefully employed to access long-term memory through the use of mnemonics and other tricks, e.g. I always remember the downwind checks for the De Havilland Chipmunk, even though I haven’t flown one for over 30 years – My Friend Fred Has Hairy Balls – Mixture, Fuel, Flaps, Harness, Hood, Brakes!
The more times that data is used in our working memory, then the more likely it is to enter our long-term memory.
Similarly, the more times data is accessed in our long-term memory, then the more likely we are to be able to recall it when needed. This fact gives support to the method of training called “over learning”, where we repeat a procedure or task many more times than is necessary just to perform to a satisfactory level. This is a positive counter-measure to guard against long periods between training and actual performance during live operations; and gives support to the concept of practicing elements of operating that have not been performed for a long time, or at least mentally rehearsing or discussing them.
Long-term memory can be said to consist of three sections, each defined by the manner in which data is stored – Semantic, Episodic and Unconsciously.
Semantic Memory is our database of facts about things, which is built through repetition and familiarity. We use the semantic memory to understand words, to “do” mathematics and to follow checklists and instructions. This does not mean that everything stored in the semantic memory is correct. If we learn an incorrect fact e.g. Chiang Mai is the capital of Thailand, then this is what we will answer, instead of Bangkok, if someone asks us what is the capital of Thailand? Similarly if we incorrectly learnt and therefore “remember” that we turn the APU on before retracting Flaps after landing, then unless we follow the Checklist we are liable to make an error.
Just because we have meaning and facts stored in our semantic memory does not necessarily mean we can always recall them, when required. Rarely used data can become inaccessible unless we happen to be reminded by some context i.e. a mnemonic (as already mentioned) or something else familiar, like a sequence of events, or a familiar experience. This is why when remembering facts it is useful to engage the imagination, other senses and even the emotions
Episodic Memory contains experiences, including knowledge of specific events; the more vivid, or emotional, then the more likely it is we will remember. And, as for all memory, the more we access and recall certain memories, then the easier they will be to access and recall again in the future. A bit like joke-telling! Unlike factual semantic memory, information (stories, if you like) held in episodic memory can change with each telling, especially with time. This is because we interpret events differently depending on many factors, one of which is our expectations of how things were, or should have been. Inconsistencies between witness reports, for the same event, are mainly due to witnesses experiencing the same event differently and then layering different interpretations on top of what they experienced.
When we are highly-skilled at a task then we can perform seemingly without too much conscious effort. Peculiarly though, the more we think about “how we are doing it” the less skilful we suddenly become! E.g. a golfer suddenly losing the ability to putt, a maestro playing a difficult piano solo getting stuck, or a pilot landing in a strong crosswind suddenly over controlling.
The stages of skill learning can be broken down into four steps:
- unconscious incompetence
- conscious incompetence
- conscious competence
- unconscious competence
It is in this last stage when the skill becomes “second nature” and we are able to conduct another task at the same time such as instruct another pilot to fly. This is because the demand on our information processing ability for automatic tasks is much reduced. Whereas if we slip back into the third stage we become aware, once more, of what we are doing, and this uses up processing capacity.
In effect we all run different dedicated motor programmes and motor sub-programmes for a variety of different skills that “kick-in” when the situation demands. Whilst we may rarely make an error in performing these skills, we sometimes initiate an inappropriate skill, at the wrong time e.g. when intending to fly an approach to overshoot (go around) we may find ourselves landing and taxiing back to the terminal. These are referred to as “action slips”.
Deciding and Acting
In the early stages of flying training, focus is on learning and developing motor skills to the point that they become automatic. However, as training progresses focus broadens to include a wider range of skills that require judgement, such as, communication, problem-solving, procedures, decision-making, planning; and also skills that require knowledge, such as performance, software and systems management. Decision-making in itself is an acquired skill, which will not be covered in depth here. However, in the context of information processing, the deciding stage is concerned with selecting the type of action that best fits the current task.
The actions we choose can be:
- rule-based, and
The information processing model shows that selected actions are concerned with correcting the “outside” world so that we can perceive progress being made in the desired direction – it is an error-correcting closed feedback loop. However, if we are sensing incomplete or false data, then our selected actions can be error-generating(open-feedback loop).
Apart from automatic motor-skills responses, our responses will be sequences of conscious actions and communications. It is common in aviation for decisions and actions to be made quickly under-pressure and therefore it is likely that accuracy will suffer in place of speed. Therefore, it is extremely important in such pressure situations to be as vigilant as possible and to purposefully put effort into raising our situational awareness. This will allow speedy anticipation of likely events but also keep our awareness broad to react appropriately to unanticipated events. As Maslow calls it flow, or as we know it from the sportsfield being in the zone.
Multi-task or Manage Resources?
Can we or can’t we multi-task?
There is no doubt that humans can drive a car and hold a conversation at the same time (we all do it routinely). However, in most circumstances we are driving a familiar car along a familiar route, and the conversation is unimportant (we can stop it anytime we need to). In these situations our mental model can rely a lot on schemata of previous experiences stored in our memory, allowing us to divide our attention, and perhaps re-tune the radio, drink coffee, chat to our passenger and drive all at the same time (not recommended!).
However, we all have a point where we quickly reach capacity and have to “dump” certain tasks. When taking a detour that requires a bit of map reading, the conversation stops, the radio is turned off (to help us concentrate) and we ask our passenger to hold the coffee. We don’t even have the capacity to think about delegating the map reading to our passenger; or, is this our ego talking - I’ve got it!
Therefore utilising the other available human resources (crew/team) when the workload increases is a skill that needs to be practised and implemented. Sometimes this decision is already made and a standard procedure exists i.e. flying monitored approaches. Similarly, when a member of your team/crew is fully engrossed in a critical task they can be helped by picking up other tasks, and should probably not be distracted.
- Decision Making
- Human Error Types
- Lessening the Effects of Visual Illusions
- Managing Somatogravic Illusions Presentation
- Memory in ATC
- Memory in ATC
- Somatogravic and Somatogyral Illusions
- Vigilance in ATM
- Spatial Disorientation
- Visual Illusions
- Green, R, G., Muir, H., et al. 1996. Human Factors For Pilots. 2nd Edition. Aldershot, England. Ashgate Publishing Limited.
- Campbell, R, D., & Bagshaw, M. 1999. Human Performance and Limitations in Aviation. 2nd Edition. Oxford, England. Blackwell Science Limited.
- ^ O’Brien, D. 1993. How to Develop a Perfect Memory. London. Pavilion Books Limited.
- ^ Noel Burch. "Learning a New Skill is Easier Said than Done." Gordon Training International
- ^ Rasmussen, J. 1986. Information Processing and Human-machine Interaction: an approach to cognitive engineering. New York. Elsevier Science Ltd.
- ^ Maslow, A, H. 1968. Toward a Psychology of Being. 2nd Edition. USA. D. Van. Nostrand Company Inc.