Study Unit HE2 - Disasters (Related Theory)

Copyright Notice: This material was written and published in Wales by Derek J. Smith (Chartered Engineer). It forms part of a multifile e-learning resource, and subject only to acknowledging Derek J. Smith's rights under international copyright law to be identified as author may be freely downloaded and printed off in single complete copies solely for the purposes of private study and/or review. Commercial exploitation rights are reserved. The remote hyperlinks have been selected for the academic appropriacy of their contents; they were free of offensive and litigious content when selected, and will be periodically checked to have remained so. Copyright © 2002, Derek J. Smith (Chartered Engineer).

First published online 09:51 11th March 2002

This version [v1.0] dated 09:51 11th March 2002

 

This is the second of three related study units on the topic of HUMAN ERROR (AND HOW TO PREVENT IT), an e-learning resource published and supported by Derek J. Smith (Chartered Engineer). The resulting body of knowledge is referred to as and when necessary from the author's ORGANISATIONAL COMMUNICATION, APPLIED COGNITIVE PSYCHOLOGY, and INFORMATICS teaching programmes. For further information, please e-mail me.

Unit Aims and Outcomes: This study unit introduces the most versatile general model of cognition, the "omega model", and then reviews the topic of cognitive error in the light of the disaster cases already presented in Unit HE1 [refresh memory now]. When you have completed the unit, you will be able to deploy with enhanced confidence and accuracy the specific skills and vocabulary listed in the corresponding Study Guide.

Unit Structure: This unit currently contains two short lessons, each contributing to the overall unit outcomes, and each with its own hyperlinked support material. Here is the learning sequence:

Lesson HE2.1: The Basic "Omega" Architecture

Lesson HE2.2: The Rasmussen-Reason Omega

Lesson HE2.3: The Busse and Johnson Omega [UNDER CONSTRUCTION]

References

 

Lesson HE2.1: The Basic "Omega" Architecture

 

We look firstly at the system ultimately to blame for most of the disasters examined in Unit HE1 [refresh memory now], namely the human cognitive system - the system of neurons and neuronal cabling which somehow elevates us to being consciously perceiving and deliberately acting biological information processors. The cognitive system has rightly fascinated us for many thousands of years, and, at the risk of stating the obvious, suffers (a) from being microscopically complex, and (b) from doing things which no philosopher has ever come close to explaining. Here are five of the more significant historical works from the last 600 years:

By the early nineteenth century, therefore, a pattern to the overall logic of biological cognition was beginning to emerge, as shown in Figure 1.1:

Figure 1.1 - The "One-Box" and "Three-Box" Models of Cognition: Here are some simple diagrams of the cognitive system:

Figure 1.1(a) gives the "null view" of how the cognitive system is internally organised, that is to say, it recognises no internal modularity, merely stimulation, S, and response, R. Descartes' concept of reflex action (above) would fall into this category.

Figure 1.1(b) shows cognition broken down into three sequentially separated modules, one dealing with input (ie. sensory) information, one dealing with output (ie. motor) information, and a third, situated in between the first two, dealing with thinking, problem solving, and decision making. Bell's analysis (above) would fall into his category, and the resulting model remains popular in introductions to cognitive psychology to this day. 

Figure 1.1(c) is logically identical to Figure 1.1(b), but has been given an arched shape. This does four important things:

  • It matches the anatomical layout of the nervous system more accurately.

  • It allows us to see the "cognitive levels" involved, not just talk about them. [Figure 1.1(c) has two such levels, but later versions of the diagram have three, four, or even more.]

  • It allows what is known as a "reflex arc" (red arrow) to pass directly from the sensory module to the motor module, without having to go through the higher functions module.

  • It fits more neatly onto the printed page.

All arched models have recently been nick-named "omega models" because the Greek capital letter omega [ W ], has the same general shape (Sloman, Scheutz, and Logan, 2000).

[three simple views of cognition]

Copyright © 2002, Derek J. Smith.

 

The pace of medical discovery now quickened significantly, with major discoveries in the areas of speech production (Flourens, 1824; Bouillard, 1825; Lordat, 1843), microscopic neuroanatomy (Baillarger, 1840), and frontal lobe pathology (Bigelow, 1850 - click for detail), and it quickened again following Pierre-Paul Broca's description of a case of what is now known as "Broca's aphasia" in 1861 (Broca, 1861 - click for detail). There followed a massive and prolonged debate about "aphasiology" (ie. the localisation of the brain functions involved in communication), and, as a result of this explosion of interest in the mind, the first European and American experimental psychology laboratories were established (both in 1875). Here are the some of the main contributions to the debate:

It was during this period that schematic diagrams started to be regularly used. For example, Lichtheim (1885) produced a perfect three-box diagram, which is still used in medical education today. However, the general rule is that if you want greater explanatory power you need to have more boxes in your diagrams, and the next logical step is the five-box model shown in Figure 1.2. Not everybody agreed, however, and in the early years of the twentieth century there was a strong backlash against cognitive modeling. Led by the American psychologist John Broadus Watson (Watson, 1913, 1914 - click for detail), the "behaviourists" insisted that it was scientifically unsafe to keep waffling on about the mind when you could not actually see it. The only safe science, in their judgement, was the study of controllable stimuli and empirically observable responses. Their cognitive model was thus a gloriously simple "no box" affair, as shown in Figure 1.3:

Figure 1.2 - The "Five-Box" Model of Cognition: In Figure 1.2(a) we show how two additional boxes can be inserted into the three-box diagram by creating a middle layer between the sensory and motor modules and the higher functions module. This then allows for two reflex arcs rather than one - an upper arc (blue arrow) serving instincts and complex reflexes, and a lower arc (red arrow) serving simple life support reflexes. Craik's (1945) model (see Section 2) falls into this category. [Click here to see a visual metaphor for this sort of three-layered architecture, namely the triple-arched "Devil's Bridge" at Pontarfynach, Wales.]

Figure 1.2(b) is logically identical to Figure 1.2(a) but has been doubled up to show what is involved when one person wishes to communicate to another along some form of communication channel (turquoise arrow). Shannon and Weaver's (1949) idealised communication system would fall into this category. 

[two more advanced views of cognition]

Copyright © 2002, Derek J. Smith.

 

Figure 1.3 - The "No Box" Model of Cognition: Here is the behaviourist view of cognitive processing. It shows stimuli, S, generating responses, R, but has chosen not to show the cognitive system at all. For behaviourists, the only things that matter are the observable and predictable relationships between S and R: no suggestions are made as to what might be going on inside the organism in between. This is why behaviourism tends to be known as "S-R psychology" or "black box" psychology.

[the behaviourist view of cognition]

Copyright © 2002, Derek J. Smith.

 

Fashion changed again in the middle of the twentieth century. Behaviourism itself began to run out of steam, and the then new science of computer programming was leading psychologists once again to theorise about how thought might be internally structured. As a result, cognitive models started to reappear. To start with they were about as sophisticated as Wundt's (above), but gradually they attracted more and more subdetail (eg. Frank, 1963; Rasmussen, 1983 - see next section; Norman, 1990). Our own model followed Craik in adopting three-stage input and output legs, and Frank (1963) in dividing the higher functions module into its short term and long term memory components (the former loosely including conscious awareness). This gave us six major modules to worry about - two sensory, two motor, one higher structural, and one higher dynamic - all arranged in the standard inverted-U shape, as shown in Figure 1.4.

Figure 1.4 - Smith (1993): Click for full-sized version with explanatory caption.

[Smith's 5-plus-1 omega diagram - 1996 version]

Redrawn from a black and white original in Smith (1993:84-85; Figure 1). This version Copyright © 2002, Derek J. Smith.

  

LESSON RATIONALE: This material is essential background knowledge when interpreting, evaluating, or constructively criticising the models of cognition presented in Lesson 2.

 

Lesson HE2.2: The Rasmussen-Reason Omega

The Big Question: "What kind of information-handling device could operate correctly for most of the time, but also produce the occasional wrong responses characteristic of human behaviour?" (Reason, 1990:125).

 

 

When human error became popular as a branch of applied cognitive psychology, it needed a model of cognition of its own. Kenneth Craik, one of many Cambridge psychologists retained by the military during World War II, settled on a three-layer five-boxed affair (Craik, 1945), and a modernised version of this is provided by Rasmussen (1983), as shown in Figure 2.1:

Figure 2.1 - Rasmussen (1983): Click for full caption.

[Rasmussen's (1983) omega diagram]

Redrawn from a black and white original in Rasmussen (1983:258; Figure 1). This version Copyright © 2002, Derek J. Smith.

 

Currently, the most influential cognitive approach to human error is that offered by James Reason of the University of Manchester [Reason, 1990, 1997; to see homepage, click here]. Reason adopted Rasmussen's three basic levels of thought, and then isolated three corresponding basic types of error. He named this all-purpose explanatory schema the Generic Error-Modeling System (GEMS), and it incorporates the following elements: 

  1. Skill-Based Errors: Skill-based errors (SBEs) are failures to behave in accordance with what would otherwise have been a perfectly good intention. They happen when good plans are poorly executed for some reason, and include slips, lapses, trips, and fumbles (Reason, 1997), as follows:

  1. Rule-Based Errors: Rule-based errors are commonly known as mistakes. They are what happens when things go to plan, but the plan itself was faulty. Reason describes rule-based mistakes as involving "either the misapplication of normally good rules, the application of bad rules, or the failure to apply a good rule" (1997:71). What is often lacking is an over-riding understanding of precisely where in the overall scheme of things particular rules fit in, and when to apply them. Here are some RB error subtypes:

  1. Knowledge-Based Errors: Knowledge-based errors (KBEs) are also commonly known as mistakes, and occur "when we have run out of prepackaged solutions and have to think out problem solutions on line" (1997:71).

The GEMS classification in shown diagrammatically in the right hand column of Figure 2.2.

 

Figure 2.2 - Reason's Generic Error-Modeling System (GEMS): This is how Rasmussen's (1983) model (left hand column) can be used as a basis for Reason's GEMS classification (central and right hand columns). The central column is a flowchart showing how problems can move up or down the system according to how well each processing type is coping with them.

[Reason's (1990) GEMS diagram]

Left hand column redrawn from a black and white original in Rasmussen (1983:258; Figure 1). Central column simplified from Reason (1990:64; Figure 3.1). Right hand column redrawn from Reason (1997:72; Figure 4.8). This combination graphic Copyright © 2002, Derek J. Smith.

 

LESSON RATIONALE: The human brain evolved to help its owner survive in jungle and savannah. It is not always able to cope in complex, highly mechanised, and often quite boring system operation tasks. The only way to design safer systems and train safer system operatives, therefore, is to increase our knowledge of the brain's strengths and weaknesses. 

    

References

REFERENCES FOR THE HYPERLINKED SOURCES ARE GIVEN IN THE INDIVIDUAL SUBFILES, QV.

Rasmussen, J. (1983). Skills, rules, and knowledge: Signals, signs, and symbols, and other distinctions in human performance models. IEEE Transactions on Systems, Man, and Cybernetics, SMC-13(3): 257-266.

Reason, J. (1990). Human Error. Cambridge, Cambridge University Press.

Sherwood, S.L. (1966). The Nature of Psychology: A Selection of Papers, Essays and Other Writings by the late Kenneth J.W. Craik. Cambridge: Cambridge University Press (1966).

Sloman, A., Scheutz, M., & Logan, B. (2000). Evolvable architectures for human-like minds. Paper presented 30th June 2000 to the ASSC, Brussels, Belgium.

Smith, D.J. (1993). The psychology of effective college governance. Part 2 - The cognitive skills. Journal of Further and Higher Education, 17:77-85.

Watson, J.B. (1913). Psychology as the behaviorist views it. Psychological Review, 20:158-177.

Watson, J.B. (1914). Behavior: A Textbook of Comparative Psychology. New York: Holt.