Progress Bars and Traffic Accidents in Taiwan
Jeffrey Mindich contributed to this post in the Freakonomics blog over at the NYT website with an interesting story about Taiwan’s solutions to traffic accidents.
About a year ago, in order to reduce the number of accidents in some intersections in the country, they introduced traffic lights with countdowns of two kinds, one in which the light counts down to zero until it turns green, in the other until it turns red.
What’s really interesting is the difference in the results with the two varieties of lights:
- In the first one, countdown to green, the number of accidents was cut in half;
- In the second one, the number of injuries doubled.
People clearly speed up when facing a green light about to turn red, but get calmer when they know in how many seconds it’s going green, and are less likely to gun it.
This translates easily to interfaces. A while ago Chris Harrison published a study called ‘Rethinking the Progress Bar‘, which shows that a progress bar that is slower towards the beginning of the process and faster towards the end is perceived by users as much faster than a linear progress bar, even if the actual time spent in both are exactly equal.
I think these are two practical examples of the same principle:
- When showing progress to users, make it seem as fast as possible, even if it brings along a slight distortion of the actual progress;
- Provide the user with practical checkpoints in the process, to discourage her from giving up on a computer-intensive or remotely processed task that invariably takes some time.
Either way, never forget you have an implicit deal with the user of never lying to her: the goal here is to improve perceived performance, not to fake benchmarks.
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