<P> Some scissors have an appendage, called a finger brace or finger tang, below the index finger hole for the middle finger to rest on to provide for better control and more power in precision cutting . A finger tang can be found on many quality scissors (including inexpensive ones) and especially on scissors for cutting hair (see hair scissors pictured below). In hair cutting, some claim the ring finger is inserted where some place their index finger, and the little finger rests on the finger tang . </P> <P> For people who do not have the use of their hands, there are specially designed foot - operated scissors . Some quadriplegics can use a motorized mouth - operated style of scissor . </P> <P> Most scissors are best - suited for use with the right hand, but left - handed scissors are designed for use with the left hand . Because scissors have overlapping blades, they are not symmetric . This asymmetry is true regardless of the orientation and shape of the handles: the blade that is on top always forms the same diagonal regardless of orientation . Human hands are also asymmetric, and when closing, the thumb and fingers do not close vertically, but have a lateral component to the motion . Specifically, the thumb pushes out from the palm and the fingers pull inwards . For right - handed scissors held in the right hand, the thumb blade is closer to the user's body, so that the natural tendency of the right hand is to force the cutting blades together . Conversely, if right - handed scissors are held in the left hand, the natural tendency of the left hand would be to force the cutting blades laterally apart . Furthermore, with right - handed scissors held by the right hand, the shearing edge is visible, but when they are used with the left hand, the cutting edge of the scissors is behind the top blade, and one cannot see what is being cut . </P> <P> Some scissors are marketed as ambidextrous . These have symmetric handles so there is no distinction between the thumb and finger handles, and have very strong pivots so that the blades simply rotate and do not have any lateral give . However, most "ambidextrous" scissors are in fact still right - handed in that the upper blade is on the right, and hence is on the outside when held in the right hand . Even if they cut successfully, the blade orientation will block the view of the cutting line for a left - handed person . True ambidextrous scissors are possible if the blades are double - edged and one handle is swung all the way around (to almost 360 degrees) so that the back of the blades become the new cutting edges . Patents (U.S. Patent 3,978,584) have been awarded for true ambidextrous scissors . </P>

When were scissors first used to cut hair