We are, I trust, all but universally familiar with the knee jerk, or patellar, reflex. A doctor taps the patellar tendon with a rubber mallet, and our leg kicks forward in response. The reaction is ...

There are lots of things kids don’t like about doctor’s visits; shots, blood tests and throat swabs top the list. One thing they love is having their knee reflexes checked. A reflex is an involuntary, ...