But as it turns out, a sideline bias in the NFL is real, and it’s spectacular. To prove it, we looked at the rates at which refs call the NFL’s most severe penalties, including defensive pass interference, aggressive infractions like personal fouls and unnecessary roughness, and offensive holding calls, based on where the offensive team ran its play.Read the full examination at the link above, but the article touches on some psychological concepts, particularly cue learning, in which our reaction is affected by the reactions of others. For instance, it's why watching a comedian live with others seems funnier than watching the same special at home alone; you laugh harder in the presence of other people. They use this to explain why factors like crowd noise have been shown to affect ref behavior in past research.
For three common penalties, the direction of the play — that is, whether it’s run toward the offensive or defensive team’s sideline — makes a significant difference. In other words, refs make more defensive pass interference calls on the offensive team’s sideline but more offensive holding calls on the defensive team’s sideline. What’s more, these differences aren’t uniform across the field — the effect only shows up on plays run, roughly, between the 32-yard lines, the same space where coaches and players are allowed to stand during play.
Of course, another important psychological factor is contingencies of reinforcement and vicarious learning. If screaming at the ref does have an impact, the coach or player who does it will be more likely to do it again. Other coaches and players watching that behavior be reinforced will also be likely to do the same thing. We may complain about or make fun of coaches that scream at the ref, but if it works, it's going to keep happening, and it's going to encourage other coaches to do the same thing, even if screaming at someone is not really their thing.
Speaking of making fun of screaming coaches, here's one of my favorite Bad Lip Reading videos: