Impulse: Why We Do What We Do Without Knowing Why We Do It

Lewis's book is a popular treatment of the psychology of impulsive behaviour — why we make purchases we did not plan, choose options we will regret, click on things we did not mean to click on. The research it summarises is familiar (Kahneman, Ariely, Thaler) but the synthesis is focused on consumer behaviour in a way that is directly relevant to product design. For product direction the most useful chapters are the ones on the cues and defaults that produce impulsive choices — the mechanics that contemporary consumer products use constantly, often without naming them. A book to read carefully and a little uncomfortably: most of its findings describe mechanisms that product teams build on purpose.