Newborn babies have a preference for the way living things move

From an animal’s point of view, the most important things in the world around it are arguably other animals. They provide mates, food, danger and companionship, so as an animal gazes upon its surroundings, it pays for it to be able to accurately discern the movements of other animals. Humans are no exception and new research shows that we are so attuned to biological motion that babies just two days old are drawn to extremely simple abstract animations of walking animals.

Animals move with a restrained fluidity that makes them stand out from inanimate objects. Compared to a speeding train or a falling pencil, animals show far greater flexibility of movement but most are nonetheless constrained by some form of rigid skeleton. That gives our visual system something to latch on to.

In 1973, Swedish scientist Gunnar Johansson demonstrated this to great effect by showing that a few points of light placed at the joints of a moving animal to simulate its gait. When we see these sparse animations, we see them for what they represent almost instantaneously.

Don’t believe me? Just look at this human walker from Nikolaus Troje’s BioMotion Lab website. With just fifteen white dots, you can not only simulate a walking adult, but you can also tell if it’s male or female, happy or sad, nervous or relaxed. Movement is the key to the illusion – any single static frame merely looks like a random collection of unconnected dots. But once they start to move in time, the brain performs an amazing feat of processing that extract the image of a human from the random dots.

Delay not deviance: brains of children with ADHD mature later than others

Attention-deficit hyperactivity disorder is the most common developmental disorder in children, affecting anywhere between 3-5% of the world’s school-going population. As the name suggests, kids with ADHD are hyperactive and easily distracted; they are also forgetful and find it difficult to control their own impulses.

While some evidence has suggested that ADHD brains develop in fundamentally different ways to typical ones, other results have argued that they are just the result of a delay in the normal timetable for development.

Now, Philip Shaw, Judith Rapaport and others from the National Institute of Mental Health have found new evidence to support the second theory. When some parts of the brain stick to their normal timetable for development, while others lag behind, ADHD is the result.

The idea isn’t new; earlier studies have found that children with ADHD have similar brain activity to slightly younger children without the condition. Rapaport’s own group had previously found that the brain’s four lobes developed in very much the same way, regardless of whether children had ADHD or not.

But looking at the size of entire lobes is a blunt measure that, at best, provides a rough overview. To get an sharper picture, they used magnetic resonance imaging to measure the brains of 447 children of different ages, often at more than one point in time.

Metabolic gene and breastfeeding unite to boost a child’s IQ

The nature-nurture debate is one of the most famous in biology, but its own nature has shifted substantially in recent years. We now know that genes and environment are not opposing agents that shape our lives separately, but partners walking hand-in-hand. More often than not, genes affect our bodies and behaviour by altering the ways in which we react to our environment.

Now, an international team of researchers have discovered a stark example of this gene-environment partnership. They found that breastfed children have higher IQ scores, but only if they have a certain version of a gene called FADS2.

The concept of IQ has been central to the nature-nurture debate for years, ever since studies in twins suggested that a large part of the variation in IQ scores could be explained through inherited genetic factors. Avshalom Caspi and Terrie Moffitt from King’s College London wanted to kill this tiresome debate finding a gene that affected IQ via the environment.

They chose to look at breastfeeding, as studies have mostly found that babies who drink their mothers’ milk have higher IQ scores, among other benefits. These higher scores persist into adulthood and across social classes. We also have a reasonable idea of how breastfeeding could affect brain development at a molecular level, and it involves fatty acids.

Five-month-old babies prefer their own languages and shun foreign accents

Discriminating against people who do not speak your language is a big problem. A new study suggests that the preferences that lead to these problems are hard-wired at a very young age. Even five-month-old infants, who can’t speak themselves, have preferences for native speakers and native accents.

The human talent for language is one of our crowning evolutionary achievements, allowing us to easily and accurately communicate with our fellows. But as the Biblical story of the Tower of Babel relates, linguistic differences can serve to drive us apart and act as massive barriers between different social groups.

These barriers can give rise to linguistic discrimination, a far more insidious problem that it seems at first. Language-based prejudices have led to horrific acts of human abuse, and even civil wars. Genocide often finds itself paired with linguicide, since a race can be killed off more thoroughly if their language follows them.

Even today, people in a linguistic minority can find themselves denied access to healthcare, or at a disadvantage when looking for jobs. The issue cuts to the heart of several ongoing debates, from the role of second languages in education to whether immigrants must become fluent in the tongue of their host country.

Early preferences

It should therefore be unsurprising to learn that we have strong preferences for our own language and for those who speak it. But Katherine Kinzler and colleagues from Harvard University, have found that we develop these preferences from an incredibly young age, before we can speak ourselves, and well before we can even hope to understand the social issues at stake.

Kinzler tested 24 infants, aged 5 to 6 months, from households that only spoke English, to see if they had any linguistic preferences. Each toddler watched videos of two women, one speaking English and the other, Spanish. The women were all bilinguals and swapped the language they used in different trials to make sure that the babies weren’t showing preferences for physical traits like skin colour.

The babies were then shown the two women side by side, but no longer speaking. They strongly expressed their preference for the English speakers by gazing at their screen for a longer time (measuring gaze time like this is a standard test used by child psychologists).

Once developed in early infancy, these preferences stick around into childhood, and most probably well beyond that. In very similar experiments, Kinzler found that older infants (10 months or so) prefer to accept toys from a woman who spoke their native language.

The babies, from either Boston or Paris, were shown alternating films of an English or French-speaking woman, who spoke for a while and then silently offered the child a toy. Two real toys then appeared on the table in front of the infant, and they were twice as likely to pick the one in front of the native speaker.

So even though the offering of the toy involved no spoken words, the infants still gravitated towards the woman who had spoken earlier in their familiar tongue.

Different accents

Infants can even pick up on subtle differences in dialect. Even when two speakers are talking in the same language, 5-month old infants will prefer someone who speaks with a native accent to someone who speaks with a foreign twang. Older children (5 years or so) will similarly prefer to befriend another child who speaks with the same accent.

At that age, children will have barely any understanding of the social circumstances that leads to different groups of people speaking the same language in different ways. And it’s unlikely that their parents had much influences, since even the 5-month-old toddlers had these preferences.

These early preferences can act as the foundations for more destructive behaviours and conflicts later on in life. But we must be very careful – an instinctive basis for a behaviour does not in any way justify it.

Instead, by telling us about the basis of linguistic prejudices, these results suggest that we must work even harder to overcome them. If they are hard-wired from an early age, then education from an early age seems like a sensible first step.

Perhaps, exposure to multiple languages early in life can soften these preferences, and it would be fascinating to see if the same results hold for babies from bilingual households.

More on languages, child development, and social conflicts:
Babies can tell apart different languages with visual cues alone
Experience tunes a part of the brain to the shapes of words
In conflicts over beliefs and values, symbolic gestures matter more than reason or money

Reference: Kinzler, Dupoux & Spelke. 2007. The native language of social cognition. PNAS 104: 12577-12580

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