One day, a few months ago, I was watching @jymmysim use Instagram and he double-tapped a photo  to “like” it. I asked why he double-tapped instead of tapping the heart, but I can’t remember what he said. I’ve been subconsciously doing it ever since.

It’s easier, really. There’s a gigantic image, nicely filtered, so why wouldn’t you double tap it? Why would you try and pinpoint a finger towards that tiny button instead?

Today I was wandering aimlessly and I finally asked myself, how the hell did he discover it?

“I would usually tap the like icon, but was scrolling too fast through the images and accidentally double tapped on an image to stop it scrolling.”

I then asked on Twitter, and got back two responses along the same lines of accidental discovery, one of replicating the double tap to reload a failed load of an image, and the last, “my 11 year old daughter.”

Not scientific or a vast sample size by any means, yet it really does reinforce the playful, exploratory nature of mobile interfaces, and the application of previously developed behaviours. There’s no overlay or suggestion anywhere in the Instagram app to like a photo in this manner. I wonder what percentage of Instagram users discover it over time though, and what frequency of photos is liked in this way.

The explicit affordance exists with that tiny button, but the double tap is so much more delightful to use. I wager that the little heart that pops up conditions us too, with Instagram patting us virtually on the heads.