The small changes can make a big difference. Facebook spent time doing in depth research to see which icon would be clicked most. This type of research isn't just the reserve of the big brands - Split testing is the bread and butter of digital marketing and anyone can do it. Next time you send an email, try testing two subject lines and see which one gets the most opens.
The Like and Share buttons both use the Facebook "f" logo today. Our hypothesis was that more people would understand the thumbs up icon on the Like button, so we conducted qualitative and quantitative tests to measure them side-by-side. The results revealed an increase in engagement, so we are switching the Like button from the Facebook “f” logo to the thumbs up icon.