The body language myth of crossing your arms
by Pierre Morsa —
The communication industry is full of myths that are repeated without any scientific backing. I recently watched this video by a former FBI body language specialist. He used his skills to help bust criminals. The first thing he does (at 1'10") is bust the myth that crossing your arms is a blocking behavior.
Bingo. I cannot agree more with this. Most people cross their arms because it’s a comfortable position, not because they have a mental block, period.
However you should not cross your arms. Just like in many countries, good manners—the etiquette—dictate that we should not put our elbows on the table when we eat, we should not cross our arms when we present, not because it’s an actual blocking gesture, but because it’s considered inappropriate.