Thursday July 26th saw the launch of SciLogs.com, a new English language science blog network. SciLogs.com, the brand-new home for Nature Network bloggers, forms part of the SciLogs international collection of blogs which already exist in German, Spanish and Dutch. To celebrate this addition to the NPG science blogging family, some of the NPG blogs are publishing posts focusing on "Beginnings".
Participating in this cross-network blogging festival is nature.com’s Soapbox Science blog, Scitable's Student Voices blog and bloggers from SciLogs.com, SciLogs.de, Scitable and Scientific American’s Blog Network. Join us as we explore the diverse interpretations of beginnings – from scientific examples such as stem cells to first time experiences such as publishing your first paper. You can also follow and contribute to the conversations on social media by using the #BeginScights hashtag.
The baby, assailed by eyes, ears, nose, skin, and entrails at once, feels it all as one great blooming, buzzing confusion; and to the very end of life, our location of all things in one space is due to the fact that the original extents or bignesses of all the sensations which came to our notice at once, coalesced together into one and the same space. There is no other reason than this why "the hand I touch and see coincides spatially with the hand I immediately feel."
This passage, so often quoted in introductory psychology textbooks, was written by William James in his 1890 volume Principles of Psychology, and it encapsulates the dominant viewpoint of developmental psychology for most of the history of the field. James wasn't the first one to articulate the idea that babies are born knowing essentially nothing of the world, of course. In 1689, John Locke wrote, in An Essay Concerning Human Understanding:
Let us suppose the mind to be, as we say, white paper [tabula rasa] void of all characters, without any ideas. How comes it to be furnished? Whence comes it by that vast store which the busy and boundless fancy of man has painted on it with an almost endless variety? Whence has it all the materials of reason and knowledge? To this, I answer, in one word, from experience.
The argument proposed by philosophers like Locke and theorists like James is that babies are born as "blank slates," ready to be inscribed upon - by experience, by learning, by culture. Infants, they argue, are equipped with basic sensory mechanisms, like vision and touch, and a powerful statistical brain that is highly skilled at detecting and learning associations between those sensory inputs. Throughout development, or so the argument goes, children learn more and more associations until their minds become more like adult minds.
At first glance, this might not seem like such a controversial idea. Human infants aren't really good at anything, after all. They're sort of useless for at least six or eight or twelve months as they sit there, soaking up knowledge and deriving statistical associations from among their senses.
One prediction that follows from this is that adults should always be better at cognitive tasks than infants. This, however, is not the case. Here's one thing that at which infants out-perform adults: distinguishing among monkey faces.
In a 2002 paper in the journal Science, Olivier Pascalis and colleagues noted that "human adults are for more accurate in recognizing individual human than monkey faces; the opposite is true for monkeys." This species difference might simply arise out of differential expertise. Monkeys could be better at identifying individual monkey faces simply because they're more familiar with monkey faces. Likewise, humans have more experience looking at human faces than at monkey faces. Human infants, however, have no experience with monkey faces and - compared with human adults - fairly little experience with human faces.
If Pascalis was right - if expertise in identifying the faces of ones' own species is the result of experience - then young infants might be equally skilled at identifying human faces and monkey faces. In other words, perhaps humans and monkeys are both born with a general "face perception" template, and through experience, they become proficient at identifying faces of their own species, while simultaneously losing the ability to distinguish among the faces of other species.
This is exactly what the researchers found. Six-month-old infants were actually able to accurately distinguish among monkey faces as well as among human faces. (By nine months, however, the ability to recognize individual monkey faces had all but disappeared. Nine month old infants' responses were already adult-like.)
What this means is, for at least the first six months of life, human infants actually outperform human adults on tasks relating to face identification. Specifically. human infants, who have quite possibly never seen monkey faces at all, are better able to distinguish among them than are human adults.
This is just one example of the power of the infant human brain. In recent years, developmental psychologists have discovered evidence that infants discriminate among speech sounds, and separate speech streams into syllables and words. They can distinguish between nouns and verbs. They perceive depth, and use that information to guide their own locomotion. They carve visual scenes into individual objects. Infants can distinguish animate objects (people, animals, and robots) from inanimate objects. They can reason about numbers. They know the difference between goal-directed and accidental actions.
In the beginning, infants have terribly low visual acuity, are unable to move around in a coordinated manner, accomplish nothing by their actions, and say nothing coherent. In a few short years, children learn a great deal about the world.
The truth is that infants come into the world with a set of really powerful cognitive structures, but because of certain developmental constraints (for example, the inability of the neck muscles to support the weight of the head, or the immaturity of the visual system), are unable to properly display or use them. The key then, is to figure out the proper testing conditions for measuring those abilities. Babies do not experience the world as "one great blooming, buzzing confusion"; rather, the confusion rested squarely on the shoulders of the hundreds of scientists who thought so.
Olivier Pascalis, Michelle de Haan, & Charles A. Nelson (2002). Is Face Processing Species-Specific During the First Year of Life? Science, 296, 1321-1323 DOI: 10.1126/science.1070223
Note: Portions of this article originally appeared in different form in two previous posts: Origins of Mind 101 and Evolutionary and Developmental Origins of Human Knowledge