It's a powerful social cue to the brain that signals you belong, you're connected, and there are others you can trust.

By following the ball's suggested arc with his eyes, the magician provides a social cue.

In turn this makes the face a less reliable social cue during social interactions.

Therefore, the social cue that they believe they saw happening in the video was nonexistent.

Ordinary people pick up social cues very quickly at a young age.