The Broker

The task of a Broker is to interpret relevant knowledge acquired by cognitive and perceptual psychologists and bring it suitably to the notice of interaction designers, thereby avoiding the need for that designer to have knowledge of cognition and perception. The task is first illustrated by an example based on the concept of Design Actions and demonstrates the implication, for two different design challenges, of certain properties of the human visual processing system. It is then argued that the task of the Broker can be eased by the definition and classification of relevant concepts, in the illustrative example those of browsing, interaction and visualization. Finally, a current need for a Broker’s expertise is illustrated in the context of the interactive and dynamic exploration of the relationships associated with a multivariable system. To explain the title of this contribution I must point out that I’m an engineer who first became an interaction designer, with a concern for visualization, in 1968 when I started to design (Figure 1) an interactive-graphic CAD system for electronic circuit design [1] that eventually (Figure 2) became a commercial product in 1985. During that time I was very much aware that the perceptual and cognitive abilities of the human being – the circuit designer in my case – would be ignored at one’s peril. Few others in the industry appeared to share my view but, as an engineer and not, definitely not, a psychologist, I had to get things done – in my case the creation, with colleagues, of the first commercial interactivegraphic CAD system for electronic circuit designers (MINNIE). I therefore had some sympathy with Isambard Kingdom Brunel because I did not have, at my disposal, all – or even a little – of the knowledge about human factors that would better inform my design. So a great deal of intuition had to be applied, and we know how dangerous a substance that can be. I did involve psychologists in my research to a limited extent, but their activities could only provide a very small fraction of the knowledge I was seeking. So for a very long time I’ve been aware of the need for some means of interpreting relevant knowledge acquired by cognitive and perceptual psychologists and bringing it suitably to the notice of interaction designers. I shall call the person responsible for doing that The Broker. To illustrate the task of a broker and how it might be supported I first present an example; to the same end I then advocate more attention to definitions and