ACS Forum: The Physics of Notation: Designing Diagramming Notations that Work review

I attended the ACS Forums monthly meeting at the Waterfront restaurant in The Rocks. The event had a great atmosphere and the people, food, and topics were excellent. I mind mapped the evening as I went through and then cleaned it up this evening, so it was a little more presentable.

The speaker was Dr Daniel Moody, Director of Ozemantics, and the topic was The Physics of Notation: Designing Diagramming Notations that Work. The talk focused on the problems of diagrams in the IT industry, and proposed a set of principals which could be used as the guide for improving the way visual languages are defined in order to improve communication between diverse groups. Dr Moody highlighted many of the current flaws with existing diagram development processes, including but not limited to,

• a 90% focus on content 10% on syntax, 
• a lack of employing visual designers 
• lack of consideration for the way the human visual system works
• intuitive and personal taste design over a measurable form 
• lack of design rationale for elements

The last one was perhaps the main focus, when an element is designed then there is little reasoning behind it. As he mentioned he was giving a similar presentation to a group and posed the question “why is the image for multiple events in BPMN a pentagon?” I must admit, I pondered it before he finished his story and assumed that each corner of the pentagon meant a direction for an event to occur thus multiple events. He then told us that the person who had designed that icon was in the room and told him “we had run out of symbols”. It makes you wonder.

The solution proposed was very interesting, in alignment with the idea of having a quality standard such as the ISO 9216 Product Quality quality model, he proposed a set of principals which could be used to give specific measures for how to create well designed visual languages. He went into detail on 3 of them, perceptual discriminability, semantic transparency, and semiotic clarity.

Perceptual discriminability is the ability to identify the differences between shapes. A circle compared to a square has a greater perceptual discriminability than a square against a rectangle. I found ArchiMate interesting, that a Business Service, Application Service and Infrastructure Service are identical in shape. I thought that colour was the key to their differences but as it was pointed out colour is not part of the specification.

 I missed noting down all the variables during the presentation, so my mind map is a tad lax there however I did find it interesting that the mind can use colour to differentiate 3 times faster than shape. It would be worth seeing a study if the same occurs for contrast, as I think colour blindness was highlighted a number of times as an issue with colour.

Semantic transparency is simply the visual equivalent of an onomatopoeia word, which is a word that sounds like the thing it is describing for example “boom”. So the visual representation of a boom should look like an explosion.

 I wonder how this would go with more abstract concepts. When you look at how a class is modelled in UML it can be modeled a number of ways depending on the view being used and the state of the object. For instance an active class, defined as “An active class is a class whose instances are active” has a notation defined as “An active class is shown as a rectangle with doubled vertical lines on the left and right sides.” An active class is something that is in action it is doing something, that same notation in flow charts means sub process.

Double lines on the road indicate do not cross, “=” is equals, and a quick search on google images turns up Double Line Stitch.  I like the double line stitch, can we suggest it to be the new image for an active class. It continues the rectangle motif through the use of negative space, and has the double lines but has many of them and aligned facing outwards indicating an active rather than passive state.

Semiotic clarity was the last principle dealt with in detail. This principal means that one symbol means one thing. Most of the languages have ambiguity in some of the shapes. BPMN has 2 shapes which mean can mean an OR gateway, UML has lines and arrows which will change meaning dependent on view, and ArchiMate has the same issue. I do suspect there are only so many ways of drawing a line so you would need to head down the road of line/shape combinations (arrow) inevitably and if there needs to be one for every meaning it may become a very heavy language depending on what it needs to explain. The goal here however is precision, being able to communicate precisely the intended meaning.

I have noted a few others in my mind map, and I will see what I can do about getting the full list.

Daniel also has a manifesto for notifications. I have them listed here though they may not be in the right order.

1. Explicit design rationale must be included
2. Explicit testing
3. Evidence based
4. At least equal effort and attention on syntax and meaning
5. Adhere to the principles

From my own experience I use diagrams all the time. On my desk are sheets of A3 paper for discussions, I carry around my “crayons” (white board markers) with at least 8 colours. I regularly use and abuse UML, flowcharts, BPMN, CRC, DFD, ERD’s and am now looking at how to add ArchiMate to my list of communication arsenal.  I found many of Daniel’s thoughts refreshing and insightful on the limitations of these visual languages and to look to ways to overcome them.