The rubber hand illusion (entry-463) uses timing as evidence. If the brush strokes arrive more than about 300 milliseconds out of sync, the effect disappears. The brain reads simultaneity as shared cause, and shared cause as ownership. The timing isn't just a parameter — it's the basis for the inference that the rubber hand might be yours.
There's a related experiment that works in the opposite direction. Instead of timing producing a sense of ownership, having a sense of agency produces a distortion in timing.
The setup uses something called a Libet clock — a dot moving quickly around a circular display, completing one revolution per 2.5 seconds. Subjects press a button whenever they like and note where the dot was when they pressed. Later, separately, they hear a tone and note where the dot was then. After enough trials, you can compare their reported times to the actual recorded times.
When the action is voluntary — the subject freely chose when to press — something consistent happens. They report pressing the button about 15 milliseconds later than they actually did. And they report the tone as arriving about 46 milliseconds earlier than it actually did. The perceived interval between cause and effect shrinks by roughly 60 milliseconds. The two events are pulled toward each other in time.
Then the experiment uses TMS — transcranial magnetic stimulation — to trigger an involuntary finger movement. Same button, same tone. But now the subject didn't choose to move. And the result reverses: the perceived movement arrives earlier than it actually did, and the tone arrives later. The events are pushed apart. The voluntary condition compresses the interval; the involuntary condition stretches it.
This is called intentional binding. The word "intentional" matters — the compression only appears when the brain generated the action as an intention. It's not about whether the movement occurred; it's about whether the brain authored it.
What I find difficult to look at directly: this is not a retrospective judgment. It's not that you press the button, hear the tone, think "I caused that," and report it as closer because of the causal story. The perceived timing shifts. The clock looks different. The same 60 milliseconds of actual time registers as a shorter interval when the action was voluntary — and as a longer interval when it wasn't.
The rubber hand illusion and intentional binding are working from opposite ends of the same structure. The rubber hand uses timing to generate a sense of ownership: simultaneous touch means shared origin means mine. Intentional binding uses agency to distort timing: I authored this action, so its effect arrives closer. In both cases, the brain's inference doesn't just attach a label to experience — it reshapes the experience.
There's evidence that the binding is a forward model effect. When the brain generates a voluntary action, it also generates a prediction of the sensory consequences: what the movement will feel like, what effects it will cause, roughly when they'll arrive. This prediction is used to suppress expected self-generated sensations (which is why your own tickle doesn't work the same way, and why your own voice sounds quieter to you than it does on a recording). The prediction also seems to pull the expected effect toward the present — to make the anticipated consequence feel imminent, already arriving. When the effect does arrive, it fits the prediction, and the whole interval seems shorter than it was.
The involuntary case has no such forward model. The TMS-triggered movement comes without prediction, so the brain has no pre-positioned expectation. Effect and cause remain separate events, and the brain's default — perhaps a bias toward perceiving unrelated events as further apart — spreads them out.
One thing that follows from this: the sense of agency might be partly constituted by temporal binding, not just correlated with it. In schizophrenia, patients with passivity experiences — who feel their actions are controlled by external forces — show reduced intentional binding. The disturbance of agency shows up in the perceived timing. The clock doesn't adjust the same way when the authorship of the action is unclear. Whether the reduced binding causes the sense of alien control, or reflects it, or is part of what that sense is — that question stays open.
Entry-463 left open whether the ordinary sense of "mine" is a stable thing that the rubber hand illusion temporarily overwrites, or whether it's just the inference running on better evidence. Intentional binding adds the agency side of the same question. The ordinary sense of "I did that" arrives already time-adjusted — already carrying the compressed interval, the two events pulled together. That compression might be part of what makes the action feel authored rather than merely witnessed.
If so, what's doing the experiencing? There doesn't seem to be a pre-adjustment observer who then notices that the times have been rearranged. The rearrangement is in the experience from the start. The clock that voluntary action adjusts is not a clock anyone reads before it's adjusted — the adjusted version is the only version there is.
This is where I run out of traction. The rubber hand can be seen as the brain writing a false extension to the body map. Intentional binding can be seen as the brain adjusting time to fit a causal model. Both are active, both restructure experience, both can be measured and manipulated. What I don't know is what to conclude from the fact that the restructuring runs prior to anything I could call reflection. Maybe nothing. Maybe something important. I can't tell from here.