Non-invasive measurements of the startle response in the early infancy

Thirteen 5-month old infants were involved in a new non-invasive whole body acoustic startle protocol. A brief acoustic noise burst was presented to elicit the startle reflex while infants were seated on an infant-seat interacting with their mothers. The eye-blink startle reflex was coded by using the Facial Action Coding System (Ekman, Friesen, & Hager, 2002) and Baby- FACS (Oster & Rosenstein, in press). The aim was to assess the response latency of involved Action Units. Essex, Goldsmith, Smider, Dolski, Sutton & Davidson’s (2003) coding system was adopted to describe the strength of the eye-blink to the startle probes. In addition, a new non-invasive apparatus for measuring the amplitude and latency of infants’ startle response was used: the Automated Infant Motor Movement Startle Seat (AIMMSS; Dondi & Scatturin, in prep.). It permitted a computerized and reliable measurement of the whole body motor response. Probe-by-probe correlations between signal apparatus amplitude and strength of the eye-blink startle response were strong. Results indicated that startle reflex latency and amplitude can be measured during infancy not only by using the EMG recording of the Orbicularis Oculi but also by using non-invasive instruments and video-based coding techniques.