Civil Engineering Reference
In-Depth Information
• How do individuals collaborate in task performance?
Assuming that we can understand these issues, it would be possible to design information
displays and other information technology that can support the operator in making
decisions. One can also understand what types of skills an experienced worker has and,
from this, what type of training an inexperienced worker would need. If the work is
carried out in teams, it should be possible to understand how people collaborate in
decision making.
Of particular interest is the study of decision making in emergency situations. Can the
team collaborate in such situations of high stress, where the physical asset of the plant is
at risk? Unfortunately it is not easy to study these aspects, since they rarely occur.
In this section we will review applied cognitive task analysis (ACTA), which was
developed by Militello and Hutton (1998). An applied cognitive task analysis emphasizes
the situational assessment that an operator has to do in order to make decisions. Let's
assume that an operator recognizes a situation as familiar. This recognition will make it
possible for her to consider important details of the task, including:
• Purpose of the task
• Information that is used for task performance
• Strategies that are used to predict task outcomes
• Action schemes to execute the task
Note that there is a similarity with Rasmussen's decision ladder, which was discussed in
Chapter 5. The operator may recognize the situation, and since it is familiar, she would
know immediately what to do. If the situation is unfamiliar, the operator may conduct a
mental simulation of the most plausible course of action, and then decide what to do. The
mental simulation is based on similar task scenarios, which will then support the operator
in decision making. If there are no similar task scenarios the situation becomes much
more difficult, and the operator will often be forced to act without information that can be
used to predict the outcome.
ACTA is intended to help the HFE practitioner to extract meaningful information
about cognitive task demands and skills required to perform a task. To obtain information
about the cognitive elements, the HFE expert will ask subject matter experts (SMEs)
using three main methods: task diagram, knowledge audit, and simulation interview.
These methods are described below (Militello and Hutton, 1998).
TASK DIAGRAM
The purpose of the task diagram is as follows:
• Provide a broad overview of a task.
• Identify difficult cognitive elements.
• Provide a surface level evaluation of the cognitive elements. Which are the most
difficult and relevant cognitive task elements? Which are the elements that take more
time and resources than other task elements?
SMEs are first asked to break the task into three to six steps or subtasks. The goal is to
get the SME to walk through the task in his or her mind, verbalizing the major steps. The
