Scientists have identified what they are referring to as the 'Not Face'. This is the expression that
everyone exhibits (across genders, cultures and even with speakers of American Sign Language) when they are communicating 'Not' interested, do 'Not' agree, do 'Not' support this.
Not only is this an expression you will make unconsciously to puncture your 'not' statement, but it is also the expression you make when you are merely thinking 'not'. Watch for this cue at your next business meeting to help you determine whether your colleagues are on board with your idea... or not!