[Evidence]

Maybe our geared powerlifters can provide insight on this as I've seen numerous meets where guys will be pulling the bar to the belly and their head is lifting as the bar is lowering. I've often questioned that if it's due to heavy loads or the motion you have to fulfill with the shirt? Many different opinions as it may just be preference. I feel you can tighten your traps and stay tight without lifting your head. Good friend of mine just competed in a PLUSA meet in new york this past saturday and said he didn't know untill a half hour before his bench that you weren't allowed to lift your head at any portion of the lift or get on the balls of your feet during the lift. He said they cited the head lift as for "safety" reasons. He's done meets now for a few years and said he never heard of anyone referring to lifting their head off the bench unsafe, but you at least have to entertain the idea. I'm sure you'll get more info here as our pl's chime in.