The Twinkle-Goes illusion impacts motor planning, and is likely perceptual in origin

Abstract

The Twinkle-Goes illusion is an apparent perceptual extrapolation of moving objects that suddenly disappear. Object disappearance must occur against a white noise background that is dynamically updating, or against an initially static white noise background that becomes dynamic within a brief time window after disappearance. Here, we have refined the critical time window for dynamic noise onset to just ∼ 20 ms after moving object disappearance. We have also successfully measured the illusion using a sensory reproduction task, that minimizes decisional biases that could have influenced the binary forced choice tasks that have previously been used to measure the illusion. This suggests that the Twinkle-Goes illusion is likely perceptual in origin. We also measured the illusion using a task where people made a saccade to the perceived moving object disappearance position, showing the illusion impacts motor planning. The magnitude of the effect in our data was ∼ 22 ms, at most. This is too slight to reflect on full compensation for delayed sensory processing in early visual brain regions (∼67 ms). However, it is possible that our measures have only partially captured the activity of an extrapolation process that is involved in a full compensation for information processing delays, in order to facilitate motor planning – but this possibility remains speculative, and we review counter arguments and evidence.