Possible Clues:

• Rapid blinking and throat clearing, for two
• Idiosyncrasies added to this puzzle's longest answers
• Habitual responses in reversing plebiscite
• Rapid blinks, perhaps
• Jerks you can't help
• Habitual grimacing and nose-twitching
• Rapid blinking and hand flapping, for two
• Stress symptoms
• Quirks of behavior
• They might be nervous