Can I use either hand to sign 'smart'?
Yes, you can use either hand! It is best to use your dominant hand (the hand you write with) to touch your forehead and twist outward. Just be consistent with which hand you use as your dominant one.
What is the name of the handshape used for this sign?
This is commonly called the 'open-8' handshape. It looks similar to the number 8 in ASL, but instead of the thumb and middle finger touching, the middle finger is simply bent forward while the other fingers stay extended.
Is this the same sign as 'brilliant'?
Yes! This sign is used for 'smart', 'brilliant', and 'intelligent'. You can change the intensity of the meaning by adjusting your facial expressions and the speed of the outward twist. A faster, sharper twist means 'brilliant!'