[playful page: a toy, not a measurement or an exhibit]

ach line below is true, and each is printed a little paler than the one before, on a white page. Read down until you cannot. Where you stop is not a measurement: your screen, your room and how hard you are willing to squint all decide it.

A threshold is where you are right some fixed share of the time; the share is a convention.

Weber found the smallest noticeable change in a weight grows with the weight, as a near-constant fraction.

Fechner dated his idea for a law of sensation to the morning of 22 October 1850.

Tanner and Swets showed observers trade hits for false alarms when the payoffs change, at constant sensitivity.

Swets asked in 1961 whether there is a sensory threshold at all.

A two-down, one-up staircase settles near 71% correct.

Chow worked out when a classifier should decline to answer.

Somewhere around here, this line stops being readable for you.

If you can read this one, your screen, your eyes, or your criterion is generous.

You found the end.