Human information processing

The quest for accident causes in the 1920s brought human fallibility into focus. Research showed that 88 per cent of the accidents were primarily caused by dangerous acts on the part of the individual worker (Heinrich, 1959). Heinrich applied an accident model (the Domino theory ), where the cause was related to the event that went wrong immediately before the occurrence of injury. These types of results followed from the central position that the human operator held (and still holds) in the control of industrial production processes. 

Surry s model focuses on human actions rather than errors and the positive contributions of the operators to safety by adequate handling of hazardous situations. Accidents occur when the demands from the environment to handle hazardous situations exceed the information-processing capacity of the human operator. The operator receives information, processes it, makes decisions and acts. The information thus has to pass through several filters , where there are possibilities of information loss or distortion. There are perceptual filters such as reduced eyesight or hearing or inadequate 

This theory is based on the assumption that the operator is able to perceive a risk level in the environment that is related to the actual risk level through a delayed feedback. The operator adapts his or her behaviour in such a way that there is a balance between the hazards that the operator is exposed to and what he or she can accept (target level of risk). It follows from this theory that measures to reduce hazards at the workplace will be followed by changed behaviour on the part of the operators such that their perceived level of risk remains the same. The only way to improve safety is to change the operators target risk level. The risk-homeostasis theory was primarily developed for situations where people voluntarily expose themselves to accident risks such as in traffic. We must expect, however, that employees at a workplace also to some extent control the risk that they are exposed to based on their own experiences and preferences. 

1 Skill-based behaviour At this level, behaviour is automated. Incoming information leads directly to an automatic response without any conscious thought. Skill-based behaviour is established through training and experience. 

2 Rule-based behaviour At this level, the operator recognises a known situation and applies a pre-stored rule or action-pattern to handle it. The rules have been developed through experiences and may be individual or collective. We find, for example, traffic safety rules to avoid collisions when two cars are on an intersecting course. 

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The first questions to be considered when designing a control panel are what information is required and how much of it will be appropriate. Too little information may increase the amount of inference that the worker is required to make to predict the state of process parameters that are not directly displayed. This is especially important for emergency situations where the human information processing system is taxed heavily with many tasks. On the other hand, too much redimdant information can overload the worker. It is essential, therefore, that the information needs of the worker are identified through some form of task analysis and worker interviews. 

Human Information-Processing A view of the human operator as an information-processing system. Information-processing models are convention-aUy expressed in terms of diagrams which indicate the flow of information throu stages such as perception, decision-making, and action. 

Rule-Based Level of Control In the context of chemical industry tasks, the type of human information processing in which diagnoses are made and actions are formulated on the basis of rules (e.g., "if the symptoms are X then the problem is Y"). 

Wesnes K and Revell A. (1984). The separate and combined effects of scopolamine and nicotine on human information processing. Psychopharmacology, 84, 5-11. 

Petrie RX, Deary IJ. (1989). Smoking and human information processing. Psychopharmacology (Berlin). 99(3) 393-96. 

Wernicke JF, Dunlop SR, Dornscif BE, et al Fixed-dose fluoxetine therapy for depression. Psychophaimacol Bull 23 164-168, 1987 Wernicke JF, Dunlop SR, Dornscif BE, et al Low dose fluoxetine therapy for depression. Psychopharmacol Bull 24 183-188, 1988 Wesnes K, Revell A The separate and combined effects of scopolamine and nicotine on human information processing. Psychopharmacology 84 5-11, 1984 Wesnes K, Warburton D Smoking, nicotine, and human performance. Pharmacol Ther 21 189-208, 1983... 

Kosslyn, S. M. (1985). Graphics and human information processing a review of live books. Journal of the American Statistical Association, 80, 497-508. 

Shiffrin, R. M., Schneider, W. (1977). Controlled and automatic human information processing II. Perceptual learning, automatic attending, and a general theory. Psychological Review, 84, 127-190. 

Rasmussen, J. Human Information Processing Human-Machine Interaction. North-Holland, Amsterdam (1986)... 

Callaway, E. (1983) The pharmacology of human information processing. Psychophysiology, 20, 359-370. 

Fogel, L. J. (1976), Human Information Processing, Prentice Hall, Englewood Cliffs, NJ. 

The human factors literature is rich in behavioral and cognitive models of human performance. Because of space limitations, however, only three generic models of human performance will be presented here. They have found extensive applications. Section 2.1 presents a behavioral model developed by Wickens (1992), the human information-processing model. Sections 2.2 and 2.3 present two cognitive models, the action-cycle model of Norman (1988) and the skill-, rule-, and knowledge-based model of Rasmussen (1986). 

Figure 1 The Human Information-Processing Model. (Adapted from Wickens 1992)...

Edwards, W. (1968), Conservatism in Human Information Processing, in Formal Representation of Human Judgment, B. Kleinmuntz, Ed., John Wiley Sons, New York, pp. 17-52. 

Human Factors and Ergonomics Society, 1195 Human information-processing model, 1014-1017... 

Many of the past efforts in which performance-related measurements have played a significant role have been directed toward basic research. Furthermore, much of this research has been aimed at uncovering the general operational frameworks of normal human information processing and not the measurement of performance capacities and their use, either alone or in combination with other capacity metrics, to characterize humans of various types (e.g., normal, aged, handicapped, etc.). However, representative models and theories provide direction for, and are themselves shaped by, subsequent measurement efforts. While there are many principles and basic observations that have some relevance, the scope of material presented later is limited to topics that more specifically support the understanding of human informationprocessing performance capacity measurement. 

A simplified, although quite robust, model that is useful within the context of human information processing is illustrated in Figure 78.1. With this figure, attention is called to systems, their functions, and major interconnectivities. At a functional level that is relatively high within the hierarchy of the human... 

FIGURE 78.1 A functional systems-level block diagram of human information-processing description of the measurement of sybsystem performance capacities. 

In considering the performance of human information-processing systems, the resource-based perspective represented by the Elemental Resource Model (Kondraske, 2000] is adopted here. This model for human performance encompasses aU types of human subsystems and is the result of the application of a general theoretical framework for system performance to the human system and its subsystems. A central idea incorporated in this framework, universal to all types of systems, is that of performance capacity. 

FIGURE 78.3 The general architecture for instruments used to measure human information-processing performance... 

Memory One of two major subsystem types of the human information-processing system that performs the function of storage of information for possible later retrieval and use. 

Speed-accuracy trade-oif A fundamental limit of human information-processing systems at any level... 

Schneider, W. and Shiffrin, R.M. 1977. Controlled and automatic human information processing ... 

Model human processor (HMP) Models human information processing in terms of processing subsystems, memories, and performance parameters Performance is modeled by assigning time values to the modePs parameters Perceptual, Long-term and working memories... 

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