Cognitive Friction

Matt at 37 Signals posted to the Signal vs. Noise blog on the subject of Crosswalk countdowns and icons today. We’ve had countdowns on some crossings here in Dublin for a couple of years. I was impressed at first by the way they reduced the number of pedestrians dodging through traffic because they were impatient for the crossing signal to change in their favour. However, the behaviour of many of these countdown crossings in Dublin has now changed in such a way as to render them useless.

These crossings used to start a countdown when a pedestrian pushed the button at the crossing. Now, there is a delay between light changes that favours the traffic. So when you push the button, the crossing doesn’t respond right away, it waits for the delay to rundown, then starts a 30 second countdown to the signal that it is safe to cross. This is a broken interaction, because it decouples the user’s action (pushing the button to cross) from the system’s response (starting the countdown). Since the behaviour of these crossings changed, people have started dodging through the traffic to cross again.

This would be no surprise to an interaction designer, who could tell you that responsiveness is more important than speed. I’d be willing to bet that people would be prepared to wait longer than 30 seconds to cross so long as the countdown started as soon as they pushed the button. Finding out how long they’d wait would be an interesting experiment.