Zeigarnik effect
Unfinished tasks nag at memory more than completed ones.
What it means
The Zeigarnik effect is the tendency to remember interrupted or incomplete tasks better than tasks that have been finished. The classic explanation, rooted in Lewin's field theory, is that an unmet goal sustains a state of task-specific tension that keeps the material accessible until the goal is discharged. The original findings were striking but later replications have been mixed, with the effect proving sensitive to motivation, task involvement, and how completion is defined. Related work suggests that merely making a concrete plan to finish a task can release the intrusive thoughts, as if the goal were partly satisfied. The effect informs ideas about intrusive thoughts, productivity, and narrative suspense.
Examples
A waiter recalls the details of unpaid, still-open orders far more clearly than those already settled.
The half-finished email you closed at 6pm surfaces in your head at midnight, while the twenty you actually sent that day leave no trace at all.
An open side-quest tugs at you for days; jot "finish the swamp map on Saturday" on a note and the tugging loosens, as though the goal were partly discharged.
First described in Bluma Zeigarnik (1927).