Hypothesis 1: An event E seems to you to to last longer than it in fact does if and only if the number of ideas that pass through your mind / the rate at which your brain is processing information when you experience E if higher / faster than usual.

Hypothesis 2 --- "the internal clock": E seems to you to last longer than it in fact does if and only if your "internal clock" ticks a larger than usual number of times while you are experiencing E.

Hypothesis 3 --- the matching hypothesis: E seems to you to last longer than it in fact does if and only if the number of seconds you spend having "an experience of E" is greater than the number of seconds E in fact lasts.

Hypothesis 4: E seems to you to last longer than it in fact does if and only if your rate of "non-perceptual mental activity" is higher than usual while you perceive E.