Some authors therefore conclude that extra-retinal signals underestimate eye speed.
This predicts that judging the temporal location of object collision should be less accurate during pursuit. To test this, we had observers estimate the collision time of two objects using a mouse-press. Displays depicted a stationary obstacle and moving target, both disappearing 1500 ms before collision. In the pursuit condition, observers pursued the target with an eye movement. In the no-pursuit condition, observers fixated the obstacle.