A common fallacy people seem to have is that the capabilities of the human brain is unlimited. The human brain for sure is extremely powerful and amazingly flexible, but not infinite. Higher intelligence and specialization comes at the cost of losing general perceptual abilities.

A study from the University of Massachusetts at Amherst showed that infants 6 months in age were capable of differentiating equally well between two human faces and two monkey faces. Nine-month old infants, however, could only differentiate between two human faces. They had lost their ability to differentiate the two different monkey faces.

The study also demonstrated that 6 month old infants could tell the difference between sounds from nearly every language while older 9 month old infants had lost this ability. It is little wonder that prevailing wisdom suggests teaching second or third languages is most efficient during childhood.

According to Scott, “what is most intriguing about these findings is that they collectively suggest that typical perceptual specialization and development is characterized by the gradual decline of abilities, not just gaining new ones.” Coincident with this decline, the brain is experiencing an exuberance of synaptic connections, followed by the pruning of these connections to adult levels.

I would assume this narrowing of perception is the same concept at work as the filtering mechanism that prevents background noise from becoming overwhelming. Your auditory system automatically filters out most background noise and other sounds that don’t concern you or your safety. If this system weren’t in place, one would quickly become overwhelmed with too much stimulus.

Similarly, I would guess infants “specialize” their recognition systems for the same reason. If you aren’t exposed to monkeys every day, and thus do not require the ability to differentiate between two monkey faces, there is no reason your brain will continue to use precious brain real estate for a skill never used. In this light, infants are perhaps one of the most impressive phenomena in existence. They are supremely capable of learning anything because they are aware of every stimuli. Their brains have not specialized in anything and are therefore aware of everything.

Imagine hearing and being cognitively aware of every sound, sight and smell in your environment. I know I would quickly go crazy. But infants do this on a daily basis until they learn what input is important and what can be ignored. Impressive indeed.