Cottagers boss Rene Meulensteen revealed last week that they had a bid rejected for the England Under-21 international and claimed that the midfielder wanted to move across London.
The Hammers have lodged an official complaint to the Premier League over Fulham's alleged tapping-up, which Allardyce believes has caused uncertainty in Morrison's mind over his future at Upton Park.
"Well, who knows? You take each day as it comes in this window," he told reporters. "This window creates a hysteria about the fact that people will tell you that somebody is going to come and get you. That could then turn your head, probably based on the money that people say you're going to make.
"Everybody as a human being is not all the same, some players will react a different way, to whatever they feel is best for them. I would probably think that across the country at every club there is a player unsettled because of mad January, the lunatic transfer window that creates havoc throughout the game.
"He's a young man, and a young man with not much experience, you have to give a bit of leeway for that scenario. He's not an experienced man in life, never mind in football. And inexperienced young players can react in many different ways. It's difficult for a manager to give advice to a young player when it comes to that because they see you probably working for the club as the manager rather than working for them."
Morrison is valued at around £10m, but Allardyce has described Fulham's bid for the player as 'derisory'.