I think Instagram relies on the concept of accidental discovery to try and get users to realize that double tap leads to Liking. IOS uses that extensively to show features and options to users which are often discovered accidentally .
With example to why Instagram went for the option of double tap to like, I believe it is because the tap is the common action associated with most interactions with Mobile and a double tap is quite easy to do and can be done quickly and also addictive. To quote this article on why double tap works :
It comes down to a matter of psychology. It’s human nature to enjoy
receiving a response from our actions. As simple as that may sound,
it’s a subtle but important part of the reason why Instagram is so
wildly popular and growing every day. We love the “double tap”. When
scrolling through pictures on our smartphone on Instagram, there’s a
“like” button and a “comment” button just as there is with nearly
every other social media application. Few people click on them. Sure,
there’s the occasional comment when a particular image strikes us, but
for the most part users do the easier and more rewarding double tap on
the image. Our reward? A flash of a heart. That’s it.
Before naysayers hop in the comments and say that it’s not a big deal,
it is. This is a fact. I have no scientific data to back it up nor do
is there any way to prove or disprove it, but instinct tells me that
we unconsciously love the action and the heart reward so much that we
like more pictures than we would if it was only the simple button. The
percentage of likes to views of an image, any image, is much higher on
Instagram that Facebook, Flickr, or any of the direct Instagram
competitors. It’s not because the pictures are that much more
I also recommend looking at this article which talks about double tap acts upon the concept of discoverablity to inform the user about a feature.
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
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
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