The limbic part of our human brain is responsible for all emotions.
A high state of emotional arousal is when performance starts deteriorating out of stress , tension , anxiety.
A basic principle of the human brain suggests that a negative emotion has a far lasting impact than a positive emotion.
Since the limbic brain and rational brain work inversely , in a state of high emotional arousal i.e. negative , effective use of symbols instead of elaborate messaging can go a long way in giving control to the prefrontal cortex as against the linbic brain to reduce the arousal.
This is how great leaders are able to stay calm and use their rational senses when confronted with difficult and emotionally charged situations.