system
Given the following post, respond as if you're commenting on Reddit:
human
[I Am Legend] Questions regarding the scene where Robert Neville got trapped.

Did he fall for one of his own traps? 

Did the Darksiders move the mannequin or was Robert Neville just having an insane episode because it was his birthday? 

Or did the Darksiders move the the mannequin and set up their own trap?
gpt
The darksiders observed his trap that he used when saving max. They reverse engineered it and put it in the water. They then set the mannequin there knowing it would attract Robert.

Robert saw the mannequinn/friend in a place it had never been before. He *knew* this was *impossible* since Robert hadn't touched it. In his frightened panicked state he shot it. Investigating, he got stuck in the trap. This is one of the first hints that the darksiders are still intelligent and not mindless predators.