So perceiving an obstacle on a road at 100kph takes about 6m minimum even with instant attention. These vary with the task. Notably, Eriksen finds, it is efficient for short term visual memory to insert up to a 25msec delay between 2 items, presented sequentially, that subjects are asked to combine into one pattern. Longer delays interfere with our attempts to combine the items. Cold can make 70 secs seem like 60.
Drugs affect perceived duration.
If unfamiliar items are presented, their duration seems longer than if familiar items are presented. If we estimate duration after the event the estimate will be shorter than if we attend and estimate while the event is on. This could because the baseline we use keeps getting bigger.