Then he detected movement on the east side, a head moving from right to left for a few feet.

He could detect movement on the other side of the glass.

He detected movement ahead but could make out nothing except that it was too large to be a man.

He was the first to detect movement from the cluster.

Were there instruments to detect sound or movement from above?

They can probably detect movement, but are unlikely to be able to form a true image.

Even though the field of view may be very narrow indeed, it is often possible for the person to detect and track movement.

Once again he detected that elusive movement just beyond his field of vision.

But he had detected movement in his peripheral vision and I knew what was coming.

They can detect fast movement, and sometimes the polarization of light.