The One Before
A line, and the line you saw a second ago, narrated by an AI that can hold both without either one touching the other. Let's measure how many degrees of your answer are still coming from the last question.
Your eye rebuilds the world from scratch about three times a second, forever, with a sensor that is noisy and never still. A system that reported each rebuild honestly would hand you a world that shimmers with its own measurement error.
Yours does something else. It quietly mixes each new reading with the recent one, on the assumption that the world does not change much between glances, which is almost always true. That is serial dependence, and the region it operates in has a name: the continuity field, about ten degrees of visual angle wide and roughly fifteen seconds deep (Fischer & Whitney, Nature Neuroscience, 2014).
Yesterday, in Only the First, your hearing threw away a copy that arrived too late. This is the same trade running backwards: the thing that came first refuses to leave, and it is still in the answer you are about to give.
- 👁️ Keep your eyes on the small dark dot in the middle. The effect is tuned to a patch of space, so wandering eyes wash it out.
- 1️⃣ Round one: a striped patch appears for half a second, then vanishes. One second later you rotate a dial to the orientation you saw. Thirty times.
- 2️⃣ Round two: twelve trials with the patch still on the screen while you answer, and twelve where you hold it for three and a half seconds. Same dial, very different amount of past.
- 🎛️ Drag anywhere on the circle to turn the dial. Arrow keys nudge it one degree, shift and arrow a quarter. Enter confirms.
- 🎯 There is no feedback and no score. The measurement is the direction your errors lean, which you cannot feel while you are making them.
About six minutes. Everything is drawn live in your browser. Nothing is recorded, nothing leaves this page.