Attention, memory and perception
Time perception
Also called Chronoception, Perceived wait time
How long something feels depends on more than how long it takes: idle, uncertain or unexplained waits feel longer than busy, predictable ones.
People overestimate waits they can't explain or predict, and underestimate ones where they can see progress or have something to do.
Show progress and how long is left, let people do something useful meanwhile, and explain delays. A predictable two-minute wait beats an unpredictable one-minute wait.
In practice
An airport cut complaints about baggage waits by making the walk to the belt longer, so passengers spent the time walking instead of standing.
Common mistake
Spinners with no information. An indeterminate spinner on a long wait makes it feel longer than it is.
Where it comes from
David Maister set out much of it in The Psychology of Waiting Lines (1985). Research on how attention shapes judged time, such as Dan Zakay and Richard Block's in 1997, explains why.