Yin asked not to be identified by her real name. A young addict in her mid-twenties, she lives in Palo Alto and, despite her addiction, attends Stanford University. She has all the composure and polish you’d expect of a student at a prestigious school, yet she succombs to her habit throughout the day. She can’t help it; she’s compulsively hooked. Yin is an Instagram addict. The photo sharing social network, recently purchased by Facebook for $1 billion, captured the minds of Yin and 40 million others like her. The acquisition demonstrates the increasing importance–and immense value created by–habit-forming technologies. Of course, the Instagram purchase price was driven by a host of factors including a rumored bidding war for the company. But at its core, Instagram is the latest example of an enterprising team, conversant in psychology as much as technology, that unleashed an addictive product on users who made it part of their daily routines.
Fitts's Law provides a model of human movement, established in 1954 by Paul Fitts, which can accurately predict the amount of time taken to move to and select a target. Although originally developed according to movement in the physical world, in human-computer interaction Fitts's Law is typically applied to movement through the graphical user interface using a cursor or other type of pointer. Fitts's Law has been formulated mathematically in a number of ways; however, its predictions are consistent across the many different mathematical representations.