Sunday, March 23, 2008

Looking, but not seeing

A recent study looked at the effects of familiarity on drivers noticing important changes in road signage. As you might expect, when drivers get familiar with a road, they look less and less at the signs because they have committed them to memory. This is basic expert behavior and is generally a good thing.

You might also expect that when the signs are changed, the familiar driver is less likely to notice the change. In this case, they changed a right of way to a yield (making it very important for the driver to slow down/stop because cars coming across the intersection will not be stopping). You might expect that familiar drivers remember the right of way sign so they don't bother looking, and therefore don't notice that it was changed to a yield.

But what this study found is that the drivers do look at the new sign. But they still don't notice the change. My suspicion is that there is so much top-down processing that they still "see" the right of way, even though it now says "yield".

There are several important consequences of this. For one, it means that when you change a design, it is important to take steps to saliently inform users of the change. Kind of like when IVR phone systems have a message that says something like "please listen carefully because the options have changed."

It also makes it important to get your design right the first time. Many web businesses are launching early betas and using the "new" design strategy to launch half-done businesses to get first mover advantage and let customer comments drive future design. I applaud the focus on users, but this study shows that there are consequences of doing this if you let users get too familiar with the early stuff. You may get stuck with some bad features.

Third, it impacts the forensic work that many of my colleagues and I do. When we explain to a jury why a driver blew right through a stop sign that is obvious from the photo of the scene, it is not because the driver was inattentive and irresponsible. It is because he/she was an expert.


Ryry the Adventurous said...

What an interesting and informative blog! Thank you!

I've recently read about a similar cognitive conundrum that affects drivers nowadays, the addition of the "all knowing GPS" system to the multi-sensory intake of the driver's environment. What are your thoughts about a hypothetical addition to a GPS to the example you presented of the expert driver?

Let's say, a driver who is used to the road they are on, is suddenly told by their GPS a direction or command that is against their typical top-down process of this routine (as in, STOP ahead instead of YIELD)? Do you think that the change in audio cue would increase the driver's chance of perceiving the new stop sign? Or would they ignore that as well?

marc said...

That is a great case. I suspect that few people pay attention to their GPS in areas where they are very familiar, so most likely it will not do anything. But if the signal is salient enough, for example a loud voice shouting "Hey dummy, there is a stop sign coming up. SLOW DOWN." Then it would work. Its the real life case in the middle where we would have to do some empirical testing to find out.

Peter said...

I am curious about this study as well, and a situation where it is critical to notice changes in the environment. For example, the detection of IEDs. I wonder if that situation, if individuals still reduce the amount of eye-movements?

marc said...

Thanks for the comment. One thing we now about life or death situations is that they are salient. So I suspect no matter how many times you drive down a road that has IEDs, you probably pay a lot of attention. I am sure there is some habituation, but at a much slower rate. This is a situation that is hard to test rigorously because we can't create life or death situations in an experiment.