We usually test babies after their second-day medical examination, before their departure from the hospital, and at most five days after birth. Mothers of selected subjects are informed of our research and proposed to participate.
Informal acceptance is followed by reading an information sheet and signing an informed consent.
The best conditions for testing is when the baby is awake, calm, and slightly hungry, since the baby is required to suck during the experiment. Even though these conditions may seem contradictory, they may be simultaneously met during a 20-minute period just before feeding. The experiment takes place in a sound-attenuated chamber. We assess overall discrimination by testing whether the experimental group increased their sucking significantly more than the control group. The experimenter just has to watch the infant.