In 1912, Max Wertheimer flashed two lights at slightly different positions in rapid alternation and noticed that at the right timing, observers didn't see two separate lights — they saw one light moving. The phenomenon depends entirely on the interval between flashes. Too short: both appear simultaneous. Too long: clearly sequential. In between, apparent motion emerges with no physical movement anywhere.
Kolers and von Grünau (1976) added a color. If the two flashes are different colors, the apparent moving dot changes color mid-trajectory — before the second flash has appeared. The brain assigns a color to a location at a moment when no stimulus at that location has yet occurred.
Subjects report the moving dot changes color somewhere in the middle of its path. The transition is localized to the midpoint in space — between the two flash positions — but its timing cannot be reported. Subjects can say where the color changed; they cannot say when.
Flash B has not appeared at the moment the color transition is perceived in mid-trajectory. The brain is drawing on information from an event that hasn't happened yet at the subjective moment of the experience.
What the simulation cannot show: whether the apparent motion involves phenomenal experience identical to real motion. No experiment has answered this.
The Orwellian / Stalinesque problem (Dennett, 1991): for color phi, the brain must somehow represent a transition to B's color before B has arrived. Two accounts are consistent with all behavioral evidence. Orwellian: the brain generates the motion with A's color, then retroactively revises the record once B arrives — falsifying the past, like the Ministry of Truth. Stalinesque: the brain delays the final percept until it has B, then presents the complete sequence as if experienced in real time — a staged performance. There is no behavioral test that distinguishes them. Both produce the same report.
The temporal location problem: subjects asked to indicate when the color change occurs press at a spatial position, not a time. The transition is localized to the midpoint of the trajectory in space; its position in time is not available for introspection. The simulation draws a gradient to represent the transition — a spatial encoding. This is not a simplification. It is what subjects actually report: a place, not a moment.