How does the Temporal Bisection Test work?
First you see a short circle (400 ms) and a long one (1600 ms), 3 times each, labelled. Then come 42 circles of 7 lengths from 400 to 1600 ms, 6 of each, in a random order. For each one you say whether it was closer to the short or the long. There is no feedback: the lengths in between have no right answer, only yours.
Each length is about 26% longer than the one before, so the steps are equal in ratio rather than in milliseconds. The circle is timed by your screen's frames, from the frame it appears to the frame it goes, and one that stays up more than 40 ms too long or too short (a hidden tab, a stalled frame) isn't scored: the same length is asked again later.
How is the Temporal Bisection Test scored?
Your result is your bisection point: the length you would call “long” half the time. An S-shaped curve is fitted to all 42 answers, and the point is where it crosses 50%. Beside it is your Weber ratio, how sharply you tell lengths apart: half the distance between the lengths you call long 25% and 75% of the time, divided by the bisection point. Smaller is sharper.
Two middles are shown for comparison. The arithmetic middle of 400 and 1600 ms is 1000 ms, halfway by subtraction. The geometric middle, the square root of 400 × 1600, is 800 ms: it is as many times longer than the short circle as the long circle is longer than it.
| Length | Times the short one | Fraction of the long one |
|---|---|---|
| 400 ms | 1× | 0.25× |
| 504 ms | 1.26× | 0.32× |
| 635 ms | 1.59× | 0.4× |
| 800 ms | 2× | 0.5× |
| 1008 ms | 2.52× | 0.63× |
| 1270 ms | 3.17× | 0.79× |
| 1600 ms | 4× | 1× |
What is temporal bisection?
Temporal bisection is a way of measuring how you judge durations: learn two, then sort the ones in between. Russell Church and Marvin Deluty (1977) trained eight rats to give one response to a short signal and another to a long one. Given durations in between, the rats split them at the geometric mean, and the spread of their judgments grew in proportion to the durations. Church and Deluty read this as the work of an internal clock.
Where do people put the middle of two durations?
Often nearer the geometric middle than the arithmetic one. Lorraine Allan and John Gibbon (1991) reported human bisection at the geometric mean. But results in people vary: Charles Kopec and Carlos Brody (2010) pooled 148 experiments from 18 studies and found peculiarities in human performance that no single model then explained. Where yours falls is a description, not a grade.
What can affect your Temporal Bisection result?
Counting, for one: it turns a judgment of time into a count, and the test asks you not to. Attention matters, because a circle you half watched feels shorter or longer than it was, and so does how well you learned the two examples. A screen that drops frames would change the lengths, which is why those circles are asked again. For a test that has you produce a time rather than judge one, try the Time Perception Test; to feel a beat, the Rhythm Test.
What doesn't the Temporal Bisection Test measure?
It measures how you sort short, visible durations against two you have just learned, not your sense of minutes or hours, and not your timing to a beat. A point nearer one middle than the other isn't better or worse. It isn't a clinical assessment.