session 3: Cognitive Dimensions - Green

Paper: T.R.G. Green (1989) Cognitive dimensions of notations. In A.Sutcliffe and L. Macaulay (Eds.) People and computers V. Cambridge UK: Cambridge University Press: 443-460.

Paper selected and presented by Martin Oliver.
(Notes below from Carey Jewitt – please add to these)

Context for the paper
Martin contextualised the paper for the group. It was a starting point, an early paper, on cognitive dimensions, work that has been developed further by the author and others in the field of cognitive science. (Sara Price has some interesting suggestions for futher readings that show how this work has been developed – Maybe you could post the links Sara?). Martin also sketched a sense of the disciplinary context that the paper comes from: the thinking through of metaphors as ways to explore and explain, predict and model how people act in the world, One purpose for doing this is to tryout, develop and test, tentative ‘laws’ (laws in a soft sense) for understanding how people think – a ‘big work in progress’ agenda.

More specifically this paper is part of Green’s work in the psychology of programming group which asked, among other questions, why can it be so hard to learn programming. This paper marks a move away from talking about the BEST programming language to thinking about fitness for purpose – in which each programming language would offer losses and gains which need to be understood in the context of use. In short a move away from a focus on the representational system per se to the system in use. Here Martin drew a parallel with linguistics and the study of Langue as opposed to Parole – this was picked up later in our discussion about the possibility (or usefulness of thinking of the possibility?) of separating system, notation, user, and environment - and the problem that would arise for cognitive dimensions of allowing the user to be too complex in a process that is about trying to define and predict (control?) their behaviour.

The question for us as a reading group seemed to be, ‘In what ways might the cognitive dimensions that the paper sketches be useful for helping us think about design, learning and pedagogy in our different research contexts?’ The paper produced an interesting discussion.

Cognitive dimensions?
According to Green, the cognitive dimensions of a notation are:
• A characteristic of the way that info is structured and represented
• One that is shared by many notations of different types
• And by its interaction with the human cognitive architecture has a strong influence on how people use the notation
• And affects whether the strategy of opportunistic planning can be pursued.

We discussed – where do these cognitive dimensions ‘come from’ – is it a model or a theory – or common sense from observations? Green appears to have developed these on the back of observational studies and the literature as one way to explain how people interact and act.

Green draws in the social context of programing by stating that ‘system=notation+ environment’ (pg 2). In our discussion there was a general sense that the differences between people are underplayed and the ways in which users/people change via their interaction with a system is not accounted for.

Some key points from our discussion of paper
here I focus on 3 of the dimensions that we discussed and seemed – in my opinion - to have most currency with the group

7.1 Hidden/explicit dependencies
This looks at the balance between what is hidden and explicit in an application (e.g. in a spreadsheet application) and what this design decision means for how people can interact with an application. In the spreadsheet example given in the paper, the higher the level of hidden dependencies between cells in the spreadsheet the more difficult it is to ensure the accuracy of data when cells are modified because the dependencies between cells are not easily recoverable. On the other hand if the algebraic model is explicit it increases the amount of data/info to deal with and this may decrease the ability of the user to recognise salience.

The design implication here is that all the information necessary/that matters to the user for what it is that they need to be able to do should be accessible and environmental support )cross references, browsers, etc) given.

7.2 Viscosity/fluidity
This dimension is concerned with the extent to which something – in this case a notation system - resists local change. We discussed the payoff here between safeguards and easiness in changing something at a local level, and the different contexts where these are useful.
Implications – viscous systems create more work for the user, - breaking track of thought and creating ‘working memory load’ . creating modules is one way of managing a viscous notation system, parcelling up aspects. There may be good pedagogic reasons for making things difficult to do. Viscosity might demand serious thinking before action – rather than evolutionary thinking…

7.3 Premature commitment
Here the focus was on generative ordering – the demands made by an application: whether a program demands that the user write in any order or in specific final text order – the extent to which the user has to look ahead imposes different degrees of commitments… this has implications for dealing with contingency of design as re-design.
Implications - The possibility of decoupling the generative order from the final text order has implications for how designs can be developed

General points re cognitive dimensions and design

Other cognitive dimensions noted in the paper included – role expressiveness, diffuseness, consistency, susceptibility, perceptual cues, cognitive off-loading.

The general sense of the group was, I think that even if the dimensions turn out not to be ‘true’ they nonetheless give a useful terminology for talking together about an aspect of a design – that they useful tools.

Cognitive dimensions appeared to offer ways of understanding the mindset of a designer – in order to understand a program/ application. They also offer a way to see how the designer/design imagines (wants to produce?) the learner/user. One point raised here is how the user is usually imagined as an individual, but this is questioned by the example of ‘extreme programming’ (where programmers work in pairs – one coding, the other checking, and alternating this role – as a way to reduce mistakes)
The question of where might the design deliberately ‘stop’ the user from acting– e.g. via the designed viscousity of the program, or what relationships are made apparenet – explicit and which hidden might be a marker of what is valued, and the expectations etc by the designer. The possibilities to customise what is hidden etc (values) was discussed in pedagogic terms.

The question ‘who decides what representation to start with?’ was asked - why talk as opposed to written, or visual , or audio? This prompted a brief discussion of the histories of representational forms, the cultural and social histories of notations and the ways in which these create positions to knowledge, boundary disciplines, create and gateway professions, It led to the question of whether meaning can exist outside of a sign and how usefully think about the relationship between sign and meaning – sign and concept, external and internal signs. This issue will be the focus of our next paper – to be announced shortly.