Just like us, babies have preferences over things they like. However, unlike us, babies can't exactly verbally communicate that to us. Do not fret! Researchers have found a way to figure out what baby preferences are with what's called "High Amplitude Sucking Rates".

Using a special pacifier handcrafted for science, all that the baby has to do is either suck faster or slower to pick between different stimuli connected to the pacifier. This is where researchers connect different audio clips to let the baby decide which one they prefer, and it's been used for many infant studies.

One of the classic experiments involved observing which voice a baby preferred hearing, their mother's or another person's voice. They gave newborns the special pacifiers that changed the voice recording they heard depending on how fast they sucked on it. The results showed that babies chose to hear their mother's voice over the other recording, which in hindsight doesn't seem surprising. Now you might be thinking, "what about dads?" researchers were so interested in this finding that they continued the study to see if babies have preference over which parent. The results found that newborns still preferred hearing the voice they heard prenatally (their mother's), but this changes as the child grows older and depending on who they spend more time with.

In another classic study, researchers had mothers starting at seven and a half months pregnant read Dr. Seus's The Cat in the Hat twice a day. Once they were born, they gave newborns the special pacifier to see if they preferred hearing The Cat in the Hat or a new book. In fact, these infants preferred hearing the story they heard in utero over another story. The pattern from these studies show that these newborns have a preference over everything they experienced prenatally, and this has been one of the many remarkable findings!