Week ten Flashcards
Key terms
Attention
In work situations, we often have to direct our attention to the performance of specific tasks. Attention describes the state of arousal in selectively concentrating on a discrete aspect of information, subjective or objective while ignoring other information. We can identify three distinct modes: divided attention, focused attention and selective attention.
Chunking
The capacity and duration characteristics of short term memory have important implications in the workplace. They explain why simple codes can be forgotten entirely or remembered incorrectly. To some extent, the reliability of short-term memory can be improved by chunking information, which describes the process of grouping information to facilitate cognitive function. For example, we would expect people to remember the telephone number 589463, but have great difficulty in recalling a longer number such as 589463542. However, we can cope a little better with long telephone phone numbers, by forming chunks of numbers, i.e. 589 463 542.
Cognitive ergonomics
Cognitive ergonomics describes the ergonomics area concerned with mental processes, such as perception, memory, reasoning, and motor response, as they affect interactions among humans and other elements of a system. One approach to the study of mental processes is to use the analogy of an information processing system such as a telecommunications system or computer. The usual procedure is to conceptualise mental processes as a sequence of information processing stages. It is assumed that, at each stage, data is processed, and a fixed amount of time is used up. Models of this type have proven to be useful for examining potential limitations in performance, although it must be noted that an orderly sequence of distinct stages doesn’t always match reality.
Compatibility
Compatibility describes the measure of the extent to which stimuli and responses match the expectations that are contained in mental models. The greater the degree of conceptual compatibility, the easier it is to process the information. For example, if symbolic signs are to be read quickly, with few errors, they should correspond to the conceptual associations that people have. Note, however, that many compatible relationships are culturally acquired.
Divided attention
When we must attend to two or more distinct tasks at the same time our attention has to be divided. Examples include talking over a mobile phone while driving a car, and reading a newspaper while eating breakfast. Another word for this sort of situation is time-sharing. Often when two or more tasks are performed, the performance of at least one task declines. This is because humans have a limited capacity to process information. This situation can be understood either in terms of the limited spare capacity model introduced in Study Guide one, or in terms of the attention resources contained in Wickens’ information processing model. If we consider Wickens’ model, we see that a common pool of attention resources is being shared by all mental processes. This would explain why performance declines as time-shared tasks become more difficult. As some tasks demand more resources from the limited supply, fewer resources are available for performing the other tasks.
Focused attention
Focused attention is required when we attend to one information source for a continuous amount of time. Carrying out telephone conversations against a background of factory noise is an example of this type of activity. The ability of people to focus their attention is influenced by the proximity, in physical space, of stimuli. For instance, if two visual stimuli are very close together it is very difficult to focus on one and completely avoid the other. Hence, close proximity can make a focusing task more difficult. Focusing attention, on the other hand, can be made easier by separating the stimuli in space or differentiating the stimuli more clearly.
Qualitative display
Qualitative displays provide information about the rate or direction of change, or about the state of a system (e.g. on or off). It should be noted that a display that is best for quantitative reading may not necessarily be best for qualitative reading tasks. The extraction of qualitative information is generally facilitated by partitioning a scale into two or more zones. For example, three zones might be used respectively for cold, normal or hot temperature. The perception of the correct reading can be further enhanced by using codes such colour, shading or shape. The use of a red zone indicating danger is a good example of colour coding.
Redundancy (as a principle in design)
describes a built in back up in a system – such as requirement for two people to perform a critical task’ or planning for flexibility in staffing to adjust for peak workload or absences. In a cognitive context, redundancy might be achieved by using a second ‘code’ to reinforce the first and increase the probability of an accurate identification, e.g. if we have a stimulus that comes in 6 sizes we could use an additional dimension, such as colour, to uniquely identify each of the sizes. Size one could be green, size two could be red and so on.
Vigilance tasks
When people perform tasks such as truck driving or quality inspection, they have to pay attention or concentrate for long periods of time. These are known as vigilance tasks.
