Cognitive Load, Training & Retraining Times, Usability, Continuity of Thinking, and Unused Components

This is crossposted with minor editing from my contribution to the AMIA Implementation Group list this morning.

We have recently completed a comparative study of two CIS/EMRs in an emergency department (ED) setting. In our discussion of the differences, we arrived at a number of theses and would be interested in your views about them.

  1. Training time to learn how to use a CIS is a direct representation of its cognitive load. Our thinking here is: the more remote a CIS is from the workflow processes and content of the users’ known processes, the greater the amount of training and retraining time required for the user. A trauma doctor once said to us about a trauma CIS:

    If it takes more than 30 seconds to learn, then it is not good enough.

    Retraining time here is the extra training time you need after the initial training and also the assistance you need from the local expert user. Our idea is that systems that match the natural workflow of the user will be easier to use, and so have higher productivity.

  2. Point-and-click interfaces break continuity of thinking and therefore cost time and make it harder to record the essential elements of the patient case. Many clinicians say it is easier to write on paper than do data entry into a CIS, and our hypothesis is that this is because point-and-click user interfaces break the continuity of thought that comes from a pen-and-paper strategy.

    It is our experience in designing many CISs that clinicians fall into one of two paradigms: holistic and atomic; that is, there are those who want to write the story, and there are those who want to atomise it into elements. We conjecture the first is a top-down approach and the second is a bottom-up approach, or alternatively, the aggregated approach and the disaggregated approach, respectively. These differences in thinking styles produce different views as to the desirability of different interface types: the latter comfortable with point-and-click interfaces; the former uncomfortable with them. We have worked with two different EDs who were at each end of this axis. Of course, practical systems are graded along this axis and no one solution is just one and not any of the other.

  3. Cognitive load is also increased by unused components; that is, the extent to which components of a CIS are not of use to the clinician needlessly add to the cognitive load. Our notion here is that it is unhelpful to continue adding functions to a CIS if they are not going to be used, as it just makes the system harder to use, on average. Alternatively, providing a CIS that has a large variety of functions, many of which will be unused, will create a time cost and stress cost for staff which will reduce their productivity/efficiency. Hence, systems should be designed to supply “not-quite-enough” functionality, and then be “readily expandable” (this implies cheaply expandable) when the clinicians are confident they know what computerisation will be of the “next best benefit”.

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