Why Speed Seems to Change When Cameras Zoom In

Cognitive behaviorist Mark Changizi explained a fascinating optical illusion using footage originally posted by optical illusion expert Akiyoshi Kitaoka in 2020 that shows how his train appeared to move slower when he zoomed in on an oncoming with his camera.

The illusion that speed decreases when zoomed is “because when one focuses on an inner portion of the movie, the optic flow angular speed is slow, and appears to fill one’s entitle visual field, which is consistent with overall lower forward speed.

Changizi further notes the specific images in the frame.

The more zoomed, the more densely packed the overhead rigging appears. So, even though you appear to be moving forward more slowly when zoomed in, the actual rate of rigging flowing by remains constant, consistent with same forward speed in all conditions. …The brain generates a perception of the anticipated next moment, thereby correcting for neural delay.

Here are Kitaoka’s original videos.

via The Kid Should See This