A Baltimore Light Rail train, stopped at a station with the doors closed.

Affordances vs. Conventions

Andrew Hinton, in his 2013 Information Architecture Summit talk, The World Is The Screen, described a framework of three modes in which information affects our perception: ecological, semantic, and digital. This is a tale of ecological perception of affordances vs. semantic perception of conventions.

I don’t live in a place with many public transit options. There’s a bus, which runs too infrequently to be of much use. But when I travel to another city alone, I often opt for public transit while I’m there. I enjoy it, and I’ve used subways, trains, and buses in New York, Chicago, Boston, DC, Orlando, Atlanta, Toledo, Rochester, Dublin, and Paris. They all work pretty much the same. The train stops, the doors open, you get in, the train goes, the train stops, the doors open, you get out. Sometimes, particularly when there aren’t many passengers, you might need to press a button or tape, or pull a cord, to indicate that you want to get out at the next stop.

At the IA Summit in Baltimore, I needed to take a day off to attend a funeral. That meant getting from Baltimore to the airport to rent a car, and light rail was a fast, cheap, and easy way to get there from where I was. The previous day I had taken the same light rail line the other direction, from the airport to my lodging in Baltimore, with no trouble. The train stopped, the doors opened, I got on, the doors closed. I became aware that Baltimore is in a slightly different universe when an out-of-town visitor wanted to get off the train. The conductor announced the upcoming station. The visitor pressed the tape to request a stop. The train stopped, he got up and stood by the door.

Nothing happened.

Uncomfortably, he looked over to another door in the car, reasonably thinking, no doubt, that since only certain doors had opened when the train stopped to pick us up at the airport, maybe he had just chosen the wrong door this time. He spend a few awkward moments looking back and forth from his door to the other doors before a number of Baltimore natives helpfully called out in cheery tones: “You have to press the green button.”

The people in Baltimore are very friendly. Should you ever choose to visit I’m sure you’ll find them delightful. Of course they didn’t need to be friendly and delightful to me that night because, having witnessed my fellow traveler’s unease, I pushed the green button like a pro when it was my turn to get out. I remembered that lesson on the buses too. The bus stopped. The door opened. I got on. The bus moved. I pressed the tape. The bus stopped. I pressed the green button. I got out.

Back to my quest to get from Baltimore to the airport. I needed to get to the airport, but I couldn’t get there from here. Not directly, anyway. Not that day. So I got off my train and waited alone at the station for the next train that would bring me to the airport. I poised myself next to a likely looking door as the train stopped.

Nothing happened.

A Baltimore Light Rail train, stopped at a station with the doors closed.

Baltimore Light Rail Train

I probably looked much like the hapless fellow traveler I had observed the previous day. I looked up and down the train for an open door, but could see none. I took a few steps back to get a better look. Still none. I walked hurriedly toward one end of the train, then the other, to get a better view of other doors. None had opened. As I searched, the loudspeaker in the station announced the direction and final destination of the train – the airport. I narrowed my focus to my original door. No affordances. Nothing to hint at how to open it. I pushed on the door, but nothing happened. The train started to roll forward slightly, then stopped, as if to say: “make up your mind!”. Then I spotted it, labeled and beside the door, just as the conductor’s slightly annoyed voice came over the loudspeaker again: “Push the green button, sir!”

The people in Baltimore are friendly, but anyone can have a bad day.

The button is a convention, not an affordance. As semantic communication, a convention is based on a shared understanding of meaning. Affordances, on the other hand, are understood naturally. They communicate directly with the body. A door handle aligned horizontally naturally means push. One aligned vertically naturally means pull. An industrial-looking button on the side of a large machine naturally means to me “Don’t Touch!” even if its label says “Push To Open Door”.

I was perceiving my ecological environment, but not my semantic environment. I suspect I was not the first or last to experience that failure on the Baltimore Light Rail line that connects the two main transportation hubs for visitors entering and leaving the city.

When you have conventions, rather than affordances, they are built on expectations. When that’s so, make sure everyone expects the same thing.

What would you change to improve the experience? One possibility is to conform to the expectations of visitors – open the doors automatically, at least on lines serving a transportation hub.

Leave a Reply

Your email address will not be published.