If you’ve ever seen an android in a film you will know the feeling.
It looks like a human, moves like a human but still ends up being a bit creepy.
Now scientists have worked out why we find such robots uncomfortable to watch – they spark conflict in our brains.
The gap between how we expect them to move and how they actually move causes confusion in the part of our brain which governs body movement.
Faced with an appearance and a reality that do not match up the brain reacts by making us feel uneasy.
The sensation will be familiar to anybody who has seen a raft of science fiction films or the Star Trek series which features the lifelike android Data.