Percy is injected with a drug that paralyzes his eye muscles. When he is instructed to try to move his eye when looking a stationary scene, his brain is able to send a signal to his eye muscles but he is unable to move his eyes. As a result, he perceives _____.
A) no movement, because his eye muscles can't move
B) no movement, because the scene is stationary
C) movement, because there is a CDS and an IDS
D) movement, because there is a CDS, but not an IDS

Question

Quizplus · Accepted Answer

Percy perceives movement because there is a Corollary Discharge Signal (CDS), which is the brain's anticipation of movement based on the motor command sent to the eyes, but no actual Image Displacement Signal (IDS) since the eyes do not move and the scene is stationary. This discrepancy can lead to the perception of movement even though there is none.

Percy Is Injected with a Drug That Paralyzes His Eye