"The cognitive capacities of near-term fetuses are even more remarkable. For example, fetuses can distinguish between two pairs of nonsense syllables ("biba" versus "babi"). How do you know? Get this--Mom says "Biba, biba, biba" repeatedly while fetal heart rate is monitored. "Boring (or perhaps lulling)," thinks the fetus, and heart rate slows. Then Mom switches to "babi." If the fetus doesn't distinguish between the two, heart rate deceleration continues. But if the difference is noted--"Whoa, what happened?"--heart rate increases. Which is what DeCasper reported.61"