You should keep your speed steady and let him switch lanes safely. You should never speed up because it could cause a crash. You should stick to your lane and be careful on who's behind you as well. If there's nobody behind you you can also reduce speed to help him do it safer. If there are people behind you you should just keep the same speed without endangering the people around you.
Pavlov used proved his theory of classical conditioning by studying salivation in dogs. He observed an unconditioned response, the salivation, that was a consequence of an unconditioned stimulus (the meat). Then, he paired the unconditioned response with a neutral stimulus (the sound of a bell), by giving the dog the meat after ringing the bell. He found that after being conditioned, the dog salivated every time he heard the bell ring, the salivation was now a conditioned response.