A failure to observe habituation in the human neonate

Abstract

Fifteen 1-day-old infants and 15 adults each received a sequence of 150 eyeblink-eliciting taps to the glabella (the flattened region of skin between the eyebrows). For all subjects, taps occurred every 4 s, an interval that was expected to produce a large decrement in response amplitude as trials progressed. Although the adults exhibited this habituation effect, the infants failed to do so: their responses at the end of the tap sequence were as large as at the beginning. Similar differences in the habituation of a startle reflex in immature versus older rats and in the habituation of the gill withdrawal reflex in immature versus older sea slugs (Aplysia) have recently been reported. © 1988.