You Can’t Walk Away From Variable Schedules

Sean Thompson

Variable ratio and interval schedules are efficient forms of partial reinforcement reward. Variability of a reward schedule is inherently unfair, but it does work very well. It’s what makes gambling so addictive.

We can use it in software design to drive engagement and retention. There are a lot of articles on this, and many of them do a good job of explaining the cause and effect. I want to explain it in a way which gives you a deeper understanding.

I want you to recognise when it’s happening to you, and I want you to be able to empathise with people receiving such schedules. If you can do that, you can save a huge amount of time and money in test and iteration cycles.

If you have a better sense of how well a system will works, you’ll implement it quicker.

I'll tell you a story. You’ll like it. You’re in it!

You’ve just been for a swim. You’re at a large indoor pool, and are heading back to the changing rooms. You’re a little tired from the workout, but you feel good. Time to hit the shower.

When you get into the changing area, you notice it’s a little cold. It wasn’t apparent when you arrived at the pool, but now you’re wet it’s uncomfortable. You find it a relief to get into the shower, as it starts to warm you up.

Quickly, you get washed. You’re still a little achy and cold, and aren’t in a rush, so you decide to take a longer shower. Stay there until you feel comfortable.

This is where our game begins.

To shower goes cold. Not freezing, but it’s not as nice as it was. Also, it doesn’t last long. A cold spell, then it’s warm again.

Then, you get a hot spell. Not enough to make you jump out, but it’s uncomfortable at first. Very quickly, you get used to it, and it feels like just what you need. Your muscles are relaxing, and it feels like your bones are getting warm. But then it passes, and we’re back to the previous warm.

On the next cold spell, you resolve to leave the shower. You shouldn’t have to put up with this. Not just yet though - you can’t leave a cold shower to cross a cold changing room. You know it’s only short lived, and so it soon passes.

But if we know the odd temperature spells come and go, there must soon be some extra warmth. It would be much easier to leave with a bit more heat in your body. So you wait, and sure enough you’re rewarded.

You can’t leave while you’re being rewarded though, and you can’t leave straight after a reward - you’ve already begun the journey to the next reward, and the lack of current reward surely isn’t the best time to finish. And you certainly can’t leave while you’re working through a cold spell. So now you can’t leave at any time.

A constantly warm shower would have allowed you to leave by now. Even the riches of a hot shower would be easy enough to walk away from. And nobody would stay in an only cold shower. You stay because you’re waiting for the right moment, but you never know when that is.

If the schedule were predictable, you could plan to leave at a point in the future - perhaps right after the next hot spell. It’s not predictable though. It’s random.

You don’t know when you’re getting rewarded, so you stay in case it’s imminent.

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