Normally when you tickle or stroke the sole of your feet, the toes flex inwards. However, when a newborn’s feet are tickled or stroked, the toes spread outwards. This is known as the Babinski reflex, or Babinski sign. It is a primitive reflex that disappears before 12 months of age.
If this reflex is seen after that, including adults, it is a sign there is something wrong with the nervous system, especially the brainstem or the spinal cord.
A primitive reflex is one shown by newborns but disappears gradually as they develop. These include reflexes such as the walking reflex, swimming reflex and crawling reflex that shows actions that they have not yet learnt, or the rooting reflex and sucking reflex that ensures the baby’s survival.