Lessons from Tufte

This entry is part 6 of 7 in the series Tracking Systems

Most users (myself included) spend most of their time in front of a computer in a kind of fuzzy autopilot mode, and anything that creates ripples on that placid lake of unawareness is going to be noticed as a disproportionately significant problem.
–David Harris, creator of Pegasus Mail

In Icons, Pegagogic Vectors, Forms Design and Posture, I said

ED tracking systems should adopt a … kiosk or coke machine posture. The soft drink companies want you to be able to, for example, continue a conversation with friends or on your cellphone as you buy a soft drink without error – so coke machines  have low cognitive friction … and part of this is that they all look the same. We want you to walk up to any computer in the ED and check the tracking screen without error – while you continue your conversation about the tPA or heparin or some other medication dosage.

Current computer displays, though improving, are of a much lower resolution than that of a well-printed page, by an order of magnitude.

Tufte points this out: when presented with a high-resolution graphic, like a detailed map, we can distinguish down to the 0.1 mm level. For instance, the screen used for printing Tufte’s book is very fine. I did some calculations, and my 1280×1024-resolution 19″ computer screen should have about 3.4 pixels/mm. Measuring on the screen with a fine ruler and a magnifying glass, I can indeed see 3-4 very-blurry pixels per mm. But looking similarly at the halftone screen of a figure on page 27 of Tufte’s Envisioning Information, I can count some 20-30 dots per mm. So my little experiment confirms nearly a 10-fold difference in print and screen resolution. As higher-resolution displays such as the Amazon Kindle arrive, resolution of computer displays is improving. But the Kindle, with 150-167 PPI (pixels per inch) still only has about 6 pixels/mm – about twice as good as my 19″ “high-resolution” monitor, but still significantly below high-quality printing.

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Natural Mapping, Search and Affordance

This entry is part 7 of 7 in the series Tracking Systems

Make things visible: bridge the gulfs of execution and evaluation.
Use technology to make visible what would otherwise be invisible, thus improving feedback and the ability to keep control.

–Donald A. Norman, The Design of Everyday Things

Norman states: Mapping is a technical term meaning the relationship between two things, in this case between the controls and their movements and the results in the world. [He goes on to describe the mapping of a car’s steering wheel to its direction of travel.] Natural mapping, by which I mean taking advantage of physical analogies and cultural standards, leads to immediate understanding.

Norman: Natural Mapping of Stove Controls

Norman: Natural Mapping of Stove Controls


In his landmark The Design of Everyday Things, Norman gives examples of the relationship of stove burner controls to the burners. Later in the book, as an example of an unnatural mapping, he gives an example of a clock whose numbers run counter-clockwise. Read the rest of this entry