Human Development
You might be wondering when and how our sensory systems develop in the first place, in order for perception to occur. It turns out that all of our senses are stimulated to some extent when we are still in the womb (prenatal), with the exception of vision. All sensory systems need to be stimulated early in life in order for them to develop normally.[16] The timeframe within which they need to be stimulated is called a critical period, and the exact timing of critical periods varies across our senses. Permanent deficits can arise if normal stimulation does not occur during a critical period.
When we are born, our visual system is less developed than our other sensory systems (since it is not stimulated prenatally. If a newborn has problems that prevent them from seeing normally in the first year of their life, they have permanent difficulties with perception of faces for the rest of their lives.[17]It is important to detect and resolve any sensory issues, e.g., eye and ear problems as early as possible[18]When you enter this world as an infant, you’re not wired full of memories that your brain will use to predict. You didn’t have a hand in creating that world, and you are not responsible for it.
Garlic Babies
If you are now wondering how psychologists can study sensation in babies that haven’t even been born yet -you are asking good questions! Indeed, it’s a pretty big claim to say that we start learning even before we are born.
Developmental psychologists have developed methods of working with prenatal and just-born infants to get a peek into how, and even if, babies can learn before they’re born.
In a study by Hepper in 1995, he wanted to know if infants could recognize a smell of a food they were exposed to before they were born – in this case, garlic. Participants were twenty mothers and their infants who were assigned into one of two conditions; a garlic condition and a non-garlic condition. The condition they were in depended on a pre-study survey that asked about garlic preferences.
The ten mothers who were in the garlic condition ate fresh garlic in their meals at least three or four times a week for the last month of their pregnancy. The non-garlic condition was just that, where the mothers didn’t eat any meals containing garlic for the last month of their pregnancy. All twenty of the mothers had normal pregnancies and had healthy babies. Also, it is important to note that the newborns were bottle fed, so were not getting any garlic exposure through breast milk.
In order to make sure the learning was truly prenatal in nature, Hepper and his team tested the infants 15-28 hours after birth. They placed the pieces of wool on either side of the newborn, making sure the infant’s head started in a neutral place not looking at either piece of wool. They were looking to see if the babies would turn towards or away from garlic (helpful knowledge – looking time and direction is a valid way to get preference data from infants!). I