Flow, a mental state, first proposed by psychology professor Mihaly Csikszentmihalyi; is characterized by a distorted sense of time, a lack of self-consciousness, and complete engagement in the task at hand. Often measured as a function of the emotional outcome, Flow is a useful tool to understand User Experience.
These are the slides of my talk at the UX India conference, held in Bangalore, at IIM Bangalore campus, October 24th-26th