# Temporal dynamics of motion compression: a lagged extrapolation account

## TL;DR

This study explores how the brain perceives motion and position, revealing a new illusion and proposing a model to explain it.

## Contribution

A new illusion is identified, and a computational model is proposed to explain dynamic position perception.

## Key findings

- A moving object appears stationary at a shifted position when surrounded by same-direction motion.
- The illusion is strongest when motion starts simultaneously and weakens with asynchrony or duration.
- The model explains motion- and saccade-induced mislocalization phenomena.

## Abstract

The visual system has been suggested to extrapolate an object’s position by integrating proximal motion signals to compensate for inevitable neural delays. This anticipatory extrapolation hypothesis is consistent with visual illusions such as the flash-lag effect, where a moving object appears ahead of a physically aligned flash, and the flash-drag effect, where the perceived position of a flash is shifted in the direction of its surrounding motion. In contrast to such motion-induced position shifts, we demonstrate an illusion in which a moving object appears to be standing still at a shifted position when surrounded by motion in the same direction. For this dissociation between perceived motion and position, we propose a computational model that incorporates the biphasic centre-surround antagonistic responses of motion detectors. In our model, positional signals derive from the temporal integration of motion-detector responses but remain unperceived during early suppression, reaching conscious perception only afterwards. The illusion was strongest when the object and surrounding motion began simultaneously, and weakened with increasing asynchrony or longer duration. The model predicts these results and accounts for several motion- and saccade-induced mislocalization phenomena, offering a unified account of dynamic position perception shaped by local and global motion signals and perceptual lag.