This apply not only the mall, even in a museum, disco, party, crowds, time perception will be altered, i suspet the key is in the moltitude moving around the person, this can be distracting, dimming the simple original task we have entering... random observation: mall with sad music sell better than those with happy music.. and so on. And this work in large numbers, having thousand entering such environments and with a substantial part being less or more influenced.