Smirk: Slight, often fleeting upturning of the corners of the mouth, completely voluntary and controllable;
Smile: Silent, voluntary and controllable, more perceptible than a smirk; begins to release endorphins;
Grin: Silent, controllable, but uses more facial muscles
Snicker: First emergence of sound with facial muscles, but still controllable
Giggle: Has a 50 percent chance of reversal to avoid a full laugh; sound of giggling is amusing; efforts to suppress it tend to increase its strength;
Chuckle: Involves chest muscles with deeper pitch.
Chortle: originates even deeper in the chest and involves muscles of torso; usually provokes laughter in others;
Laugh: Involves facial and thoracic muscles as well as abdomen and extremities; sound of barking or snorting;
Cackle: First involuntary stage; pitch is higher and body begins to rock, spine extends and flexes, with an upturning of head;
Guffaw: Full body response feet stomp, arms wave, thighs slapped, torso rocks, sound is deep and loud; may result in free flowing of tears, increased heart rate, and breathlessnessy strongest solitary laughter experience;
Howl: Volume and pitch rise higher and higher and body becomes more animated;
Shriek: Greater intensity than how; sense of helplessness and vulnerability;
Roar: Lose individuality; i.e., the audience roars!
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