Habit formation
The process by which repeated behavior in a stable context becomes automatic, triggered by cues rather than decisions.
What it means
Habit formation is the gradual development of automaticity: when a behavior is repeated consistently in the same context and followed by reward, control of the action shifts from deliberate, goal-directed intention to a cue-driven, automatic response. The mechanism is context-dependent repetition — a stable cue (time, place, preceding action) becomes reliably linked to the behavior, so it eventually runs with little thought or motivation. Research suggests habits take a variable and often long time to form (commonly cited around two months on average, with wide individual range), and that they are robust precisely because they no longer depend on willpower. This robustness is double-edged: good habits persist effortlessly, but bad ones resist intention, and habits formed in one context can collapse when the context changes (a move, a new job). It matters because durable behavior change usually means engineering habits, not sustaining motivation, since motivation is finite and automaticity is not.
Examples
Flossing right after brushing every night anchors the new behavior to an existing cue, so within weeks it happens automatically without any daily decision to do it.
Leaving running shoes by the door and heading out straight after the morning alarm ties the run to a fixed cue; after two months the shoes, not willpower, start it.
Someone who has gone to the gym every lunchtime for years stops entirely after changing offices — the habit was welded to the old building's route, not to the intention.
First described in Wood & Neal (2007); Lally et al. (2010).