felt duration and clock duration are not the same measurement.

The standard account of how animals and people time an interval: a pacemaker emits pulses, a switch lets them into an accumulator, and the count is compared against memory. Its signature prediction is that timing error scales with the interval — so uncertainty grows the longer you wait.

1. Gibbon · 1977

   Scalar expectancy theory and Weber's law in animal timing

   Psychological Review, vol. 84, no. 3, pp. 279–325 · doi:10.1037/0033-295X.84.3.279

   The founding statement of scalar expectancy theory, and of the idea that timing variability is proportional to the duration being timed.

2. Gibbon, Church & Meck · 1984

   Scalar timing in memory

   Annals of the New York Academy of Sciences, vol. 423, no. 1, pp. 52–77 · doi:10.1111/j.1749-6632.1984.tb23417.x

   Sets out the pacemaker–accumulator information-processing model that most later work on interval timing argues with or builds on.

3. Merchant, Harrington & Meck · 2013

   Neural basis of the perception and estimation of time

   Annual Review of Neuroscience, vol. 36, no. 1, pp. 313–336 · doi:10.1146/annurev-neuro-062012-170349

   A review of where timing lives in the brain, and of why no single dedicated clock organ accounts for the range of durations people handle.

Duration is not read off a dial. How long something felt depends on how much attention was pointed at time itself, on arousal, and on the state of the body while it passed.

1. Block & Zakay · 1997

   Prospective and retrospective duration judgments: a meta-analytic review

   Psychonomic Bulletin & Review, vol. 4, no. 2, pp. 184–197 · doi:10.3758/BF03209393

   Across twenty experiments, knowing in advance that you will be asked how long something took changes the answer: prospective judgements run longer and vary less than remembered ones.

2. Seifried & Ulrich · 2010

   Exogenous visual attention prolongs perceived duration

   Attention, Perception, & Psychophysics, vol. 73, no. 1, pp. 68–85 · doi:10.3758/s13414-010-0005-6

   Drawing attention to a stimulus makes its duration feel longer — a direct demonstration that attention is part of the measurement.

3. Droit-Volet & Meck · 2007

   How emotions colour our perception of time

   Trends in Cognitive Sciences, vol. 11, no. 12, pp. 504–513 · doi:10.1016/j.tics.2007.09.008

   Reviews how arousal and emotional valence push perceived duration in opposite directions, by changing both clock speed and attention to time.

4. Wittmann · 2009

   The inner experience of time

   Philosophical Transactions of the Royal Society B, vol. 364, no. 1525, pp. 1955–1967 · doi:10.1098/rstb.2009.0003 · open access

   Argues that bodily and emotional states are not a distortion applied to duration but part of how duration is encoded in the first place.

1. Aschoff · 1998

   Human perception of short and long time intervals: its correlation with body temperature and the duration of wake time

   Journal of Biological Rhythms, vol. 13, no. 5, pp. 437–442 · doi:10.1177/074873098129000264

   In subjects isolated from all time cues, produced intervals of five and ten seconds tracked body temperature, while produced hours tracked how long the person had been awake — evidence that short and long durations are not timed by the same mechanism.

Uniform clock time is a nineteenth-century administrative achievement. It was pushed through to make timetables, shifts and telegraph signals agree with each other.

1. Thompson · 1967

   Time, work-discipline, and industrial capitalism

   Past & Present, vol. 38, no. 1, pp. 56–97 · doi:10.1093/past/38.1.56 · jstor.org/stable/649749

   The classic account of the shift from task-oriented work to clock-oriented work, and of time-discipline as something taught rather than natural.

2. Bartky · 1989

   The adoption of standard time

   Technology and Culture, vol. 30, no. 1, p. 25 · doi:10.2307/3105430

   How standard time actually came in — driven by railway and telegraph coordination rather than by any improvement in how people experience an afternoon.

Two further histories, and the horological lineage of measuring duration by scent and by flame, are on the learning page.