Every time the light go out, Socky gets lost. You have to search him. Put your finger on the screen and a sound will indicate how close you are (works like pot hitting). Once you are confident you found the position where he is hiding, use one of your flashlights. In case you were right and detected him, you get points as a reward.
But pay attention to the remaining flashlights and time. Every round there is less time to find Socky.