Category: Babies

Why "reaching training" for babies might soon become a thing

Babies’ first motor skills – how early they learn to reach for things and explore them – are related to their later abilities, both motor skills (such as crawling and walking) and skills in other domains, such as their vocabulary. This raises the intriguing possibility that those early motor abilities facilitate subsequent developments, triggering what psychologists call a “developmental cascade”. This makes sense – for example, a baby who can already reach for and interact with things tends to attract more attention from his or her parents, which in turn is likely to foster further broad developmental progress.

A new study in Developmental Science has tested this cascade theory with a training intervention. The researchers in America recruited a group of 14 three-month-old babies and their mothers, and for two weeks, the mothers were instructed to engage their infants in ten minutes per day of active reaching training. This involved the babies wearing Velcro covered mittens and being encouraged to reach for Velcro covered toys, with the Velcro helping the babies to successfully reach for and obtain the toys. A comparison group of 11 three-month-olds and their mothers spent the same time performing a passive version of the training, without the Velcro, in which the mothers touched the toys to their infants’ hands. The babies also completed a basic test of their grasping skills, before and after their training.

When the babies were 15 months old, they returned to the psychology lab and were videoed playing with a bead-maze toy (a wooden block with metal wires attached, along which beads could be pushed). A further control group of fifteen 15-month-old babies who hadn’t participated in any training at three months were also videoed playing with the toy.

The babies who’d received the active reaching training at 3 months of age showed more precocious motor and attentional skills when playing with the toy, as compared with the two other groups. For example, they spent more time looking at, grasping and rotating the toy and less time being distracted. Moreover,  the babies’ post-training, but not pre-training, grasping abilities at age 3 months were related to their play behaviour at 15 months, consistent with the idea that the early training had had a long-term influence.

The study involved only a small number of children, all of whom were from highly educated families, and this wasn’t a true randomised controlled trial because the no-training control group were recruited later and only visited the lab once. Nonetheless, these are fascinating results that suggest infants’ very early motor abilities have long-lasting knock-on effects on their later development, and that it may be possible to intervene early to assist this process. The researchers said intervening in this way might be particularly beneficial to babies born preterm and children at risk for autism, who are known to show motor delays and reduced grasping movements early in infancy.


Libertus, K., Joh, A., & Needham, A. (2015). Motor training at 3 months affects object exploration 12 months later Developmental Science DOI: 10.1111/desc.12370

further reading
How babies go sole searching
10 surprising things babies can do

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

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A US sociologist has accused baby psych labs of being creative with their results

By Christian Jarrett

A US academic who spent 16 months embedded in three American psychology baby labs reports that he observed numerous examples of researchers cutting corners and bending the rules of science. Writing in Socius, David Peterson at Northwestern University in Chicago says that doing psychology research with babies is so challenging and costly that developmental psychologists routinely do things like: checking early in a study whether their results are going to be significant (and abandoning or changing tack if they don’t look promising); comparing notes with other supposedly independent judges when coding whether babies are looking at a stimulus; taking a relaxed approach to task instructions (for example, telling mothers that it doesn’t really matter too much if their eyes are closed or not during a task); and making up post-hoc explanatory stories to account for surprising results, with those stories later presented as the initial impetus for the research. As an example of that last point, Peterson quotes an exchange between a grad student and her mentor: “You don’t have to reconstruct your logic. You have the results now. If you can come up with an interpretation that works, that will motivate the hypothesis.”

The open-access paper, presented as an ethnographic study of baby labs, comes at a time when psychology is working hard to tighten up its research practices, for example through the Center for Open Science and the introduction of registered reports in which planned hypothesis-driven methodologies are accepted for publication before their results are in. Peterson says that he “took part in nearly every aspect of laboratory life”, that he took notes throughout the course of each day, and recorded all direct quotations immediately. “Ultimately I argue that developmental psychologists meet disciplinary requirements through a set of strategies that bend results toward statistical significance,” he writes.

The Baby Factory
Difficult Research Objects, Disciplinary Standards, and the Production of Statistical Significance

Christian Jarrett (@Psych_Writer) is Editor of BPS Research Digest

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Most acts of aggression by toddlers are unprovoked

Watching toddlers pinch, hit and bite each other doesn’t fill you with confidence about human nature. But there’s no need to be down about it – the little devils don’t yet have the self-control to manage their anger and frustration, that’s all. Right?

Not according to a new study published in Developmental Science, which is the first to systematically investigate the use of force in infants from age 11 months and up. Audun Dahl at the University of California, Santa Cruz, finds that in fact most of the time, the use of aggression* by toddlers is unprovoked.

Dahl interviewed 74 middle-class mothers with infants who were aged on average 16 months (range 11 to 24 months; 33 female). He asked these mums to describe a recent time when their child harmed someone else. Analysing the mothers’ stories, he found that in 76 per cent of the situations, the act of aggression was unprovoked and the aggressive infant did not show any signs of visible distress. This chimes with past research in which mothers reported their toddlers mostly showed signs of pleasure when they caused upset to other people.

Meanwhile, 26 per cent of the aggressive acts were provoked, for example to regain a toy from a sibling (and usually accompanied by distress), and 3 per cent were accidental. Overall, the stats argue against the idea that babies and toddlers mostly hit, scratch and bite as a way to vent their anger or frustration because they haven’t yet developed enough self-control.

To get more evidence, Dahl filmed 26 more infants (11 female) in their own homes for 2.5 hours each visit, always in the company of the child’s mother and a sibling. When he first visited each child, they were 14-months-old, then he returned when they were 19-months and 24-months-old. Analysing the videos for acts of aggression, he found that 49 per cent of the time the use of force was unprovoked, 43 per cent of the time it was provoked, and 8 per cent of incidences were accidental. Parents were the most frequent targets of aggression, followed by siblings and pets.

Zooming in on the acts of unprovoked aggression, most of the time these appeared to be what Dahl calls “explorative force”, for example to get attention, and there was rarely evidence that the aggressive infant was distressed. Less often, these unprovoked attacks were actually “miscalibrated force” – for example hitting the dog over the head when the probable intent was to stroke him.

More clues come from the infants’ personality: the toddlers who scored higher on their tendency to show pleasure tended to be the ones who committed more acts of unprovoked aggression, again suggesting they were using force as a form of fun interaction, rather than in rage. Also, provoked and unprovoked aggression showed different developmental trajectories. Provoked use of force increased consistently over time whereas unprovoked use of force rose at first, peaked at around 18 months, then decreased when the children were aged two.

These developmental results fit the idea that provoked aggressive acts are a symptom of toddlers’ ongoing lack of self control (and growing wilfulness) whereas their more frequent unprovoked aggression is more related to exploration and attention-seeking, combined with a relative lack of understanding about other people’s pain. Unprovoked acts presumably became less frequent from 18-months onwards as the toddlers learned that their aggression hurts others, or as they became more sensitive to other people’s distress. Complementing this account, Dahl found that unprovoked aggressive acts were especially likely to elicit negative reactions from parents or siblings, which presumably helped the toddlers learn to refrain from this behaviour.

Dahl concluded that his results show “that infants’ use of force against others is more diverse than typically assumed”, and he said more research on the topic is now needed in other settings and cultures to better understand how young children come to realise that unjustified aggression is wrong.


Dahl, A. (2015). Infants’ unprovoked acts of force toward others Developmental Science DOI: 10.1111/desc.12342

*Note: Audun Dahl prefers not to describe infants’ use of force as “aggression” which implies the intent to harm, which he says is “difficult or impossible to assess in infants”. I chose to use a mix of descriptive words to avoid repetition, to resonate with readers’ everyday experience (parents rarely speak of “acts of force” but they do fret about their children’s aggression), and also because Dahl’s own analysis actually distinguishes between acts of unprovoked force which were apparently deliberate and those that were “miscalibrated force” – i.e. any harm was accidental.

further reading
“I’m really good with my hands and I hit him” – Children’s descriptions of harming siblings and friends
Systematic evidence of fake crying by a baby
10 Surprising Things Babies Can Do

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

Our free fortnightly email will keep you up-to-date with all the psychology research we digest: Sign up!

Study uncovers dramatic cross-cultural differences in babies’ sitting ability

Paediatricians’ offices are often adorned with a developmental milestone chart for infants, and they always show the same “normal” age-typical progression, from sitting to crawling to walking. But these expectations (e.g. 25 per cent of infants achieve independent sitting by 5.5 months) are rather misleading because they’re derived solely from research on Western babies conducted back in the 1930s and 1940s. A new study, published recently in the Journal of Cross-Cultural Psychology, aimed to broaden our understanding of what constitutes typical sitting ability, by observing five-month-old infants from six different cultures: Argentina, Cameroon, Italy, Kenya, South Korea, and the United States.

Lana Karasik and her colleagues also departed from previous research by observing babies in their home environment rather than in a psychology lab. Specifically, a researcher local to each of the six cultures visited 12 mother and baby pairs in their homes for one hour. These sessions were taped and coded later based on where the babies were (i.e. in their mothers arms, on the ground, or on baby or adult furniture), their body position (sitting or lying etc) and how close their mother was to them. The mothers didn’t know that the study was about infant sitting ability.

Overall, one third of the infants were able to sit independently, defined as sitting without support for at least one second. But there was significant cross-cultural variation. For example, just two of the US infants displayed independent sitting and none of the Italian infants, compared with 8 of the Kenyan infants (67 per cent) and 11 of the Cameroonian infants (92 per cent). There was also a wide-range of sitting proficiency, in terms of how long infants sat independently in a single bout. For example, the shortest bout was 2.4 seconds, while the longest was 28 minutes (achieved by a Cameroonian baby).

Figure from Karasik et al, 2015.

These cultural differences were mirrored by differences in the opportunities the infants were given to sit independently. For example, infants from the US, Argentina, South Korea and Italy spent most of their time in places that provided support, such as a strapped into child’s furniture or in their mother’s arms. By contrast, infants in Kenya and Cameroon spent most of their sitting time on the floor, or on adult furniture where they had to learn to balance themselves. Mothers in Kenya and Cameroon also tended to spend more time further away from their babies. One Kenyan mother spent 13 minutes out of reach of her baby as he sat independently on adult furniture (by the way, he didn’t fall off the furniture, and neither did any other babies in this research).

It’s tempting to infer that the cultural parenting practices in Kenya and Cameroon may have encouraged some of the infants in those cultures to acquire more precocious sitting abilities (on average). But of course this was a purely observational study with small samples, and we can’t know whether the infants’ abilities influenced their parents’ behaviour or vice versa (in fact, it’s probably a bit of both). It’s also important to note, as the researchers do, that there was a huge amount of overlap in sitting ability across the cultures (e.g. some US infants sat independently longer than some Kenyan and Cameroonian infants), and there is also a large amount of variation within the cultures. Because of this, Karasik and her team say it is inappropriate to talk of babies in some cultures being uniformly more precocious than babies in others.

Infant sitting is a very important skill – it frees their hands to explore objects and interact more easily with adults. Given this, it seems amazing that most of what we know about the development of sitting ability is based on dated, lab-based research conducted almost exclusively in Western countries. “Had we not looked beyond onset ages [the simplistic idea that a child is either a sitter or not], ventured outside the laboratory, and studied samples of infants from six cultures across the globe,” the researchers said, “we would never have known that at five months, some infants can safely sit on high benches for extended periods without the support of adults nearby.”


Karasik, L., Tamis-LeMonda, C., Adolph, K., & Bornstein, M. (2015). Places and Postures: A Cross-Cultural Comparison of Sitting in 5-Month-Olds Journal of Cross-Cultural Psychology, 46 (8), 1023-1038 DOI: 10.1177/0022022115593803

further reading
Why do toddlers bother learning to walk?
For infants, walking is more than just another step in motor development
10 surprising things babies can do
How babies go sole searching
Toddlers don’t take the risk of entrapment seriously

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

Our free fortnightly email will keep you up-to-date with all the psychology research we digest: Sign up!

10 Surprising Things Babies Can Do

Baby with wearing towel over headHuman infants are helpless. At first they can’t even support the weight of their own heads. Crawling and walking take months to master. Compare this with the sprightly newborns of other mammals, such as kittens and foals, up and about within an hour of their birth. There are several theories as to why human development is so protracted – among them that this extra time is required for the human brain to develop. This post side-steps such debates and focuses on 10 studies hinting at the surprising abilities of babies aged up to one year. The research digested below suggests the infant mind is far more sophisticated than you might imagine:

Babies can meet a person once and remember them for years 
We begin with a study in which 3-year-olds watched two videos shown side by side, each featuring a different researcher, one of whom they’d met once, two years earlier. The children spent longer looking at the video showing the researcher they hadn’t met. This is consistent with young children’s usual tendency to look longer at things that are unfamiliar, and it suggests they remembered the researcher they’d met once, when they were aged just one. Of course the phenomenon of infantile amnesia means these early long-term memories will likely be lost in subsequent years.

Babies can tell a human from a zombie (or a monkey)
Six-month-old and 12-month-old babies viewed pictures of cartoon human faces. Some of the faces looked creepy because they had zombie-style goggle eyes. Just like adults, the 12-month-olds (but not the 6-month-olds) spent longer looking at the faces with normal eyes. The researchers think this shows that by age one, human infants experience the “uncanny valley” effect – an aversion to creatures that are “almost human”. Another study published in 2011 found that 3-month-olds preferred looking at human faces or bodies than the bodies or faces of non-human primates, suggesting they already had some knowledge of what humans look like.

Babies can fake cry
Last year a Japanese researcher captured on video an instance of apparent feigned distress by an 11-month-old. Hiroko Nakayama filmed two babies in their homes for 60 minutes twice a month, for six months. One baby only ever cried after displaying negative emotion. However, on one occasion, the other baby (“Infant R”) was caught on camera laughing and smiling, then crying suddenly and briefly, then displaying positive emotion again. “Infant R appeared to cry deliberately to get her mother’s attention,” said Nakayama, [then] she showed smile immediately after her mother came closer.”

Babies can tell the difference between a dirge and a happy tune
For this study researchers played music to babies through speakers located either side of a face. They waited until the babies got bored and started looking away, then they changed the mood of the music – either from sad to happy, or vice versa. This mood switch made no difference to three-month-olds, but for the nine-month-olds it was enough to rekindle their interest and they started looking again in the direction of the face.

Babies have artistic tastes
After nine-month-old babies had grown bored of looking at a Monet paintings, their interest was piqued by the sight of a Picasso. However, the reverse wasn’t true: after time spent looking at Picasso, the babies preferred to look at more Picasso than at a new Monet. The researchers aren’t sure why Picasso holds such appeal, but it may have to do with the greater luminance of his paintings.

Babies can predict your intentions
Research published in 2006 found that 12-month-old babies, like adults, showed anticipatory eye movements when watching someone placing toys in a bucket. That is, their eyes jumped ahead to the bucket as if anticipating the person’s goal. Six-month-olds didn’t show this ability, they kept their eyes fixed on the toys. “We have demonstrated that when observing actions, 12-month-old infants focus on goals in the same way as adults do,” the researchers said.

Babies can hear speech sounds that you can’t
As babies develop they become attuned to the speech sounds relevant to their native language. Before this happens, they can detect all phonetic contrasts in human speech, including those that adults in their culture cannot. Take the example of the /r/ and /l/ sounds in English, which Japanese adults struggle to distinguish. Prior to 6-months, Japanese babies can distinguish these sounds as reliably as a baby raised in an English home.

Babies can show contempt
A study from 1980 involved adults looking at videotapes of babies (aged up to 9-months) as they pulled various facial expressions in response to real life events, including playful interactions and painful injections. The adults were able to reliably discern eight distinct emotions on the babies’ faces, including: “interest, joy, surprise, sadness, anger, disgust, contempt, and fear.”

Babies rehearse words long before they can speak
For a study published this year, researchers scanned 7- and 11-month-old babies’ brains as the infants listened to speech sounds. The psychologists observed activity in motor-related parts of the babies’ brains, suggesting that the babies were already rehearsing how to produce the sounds themselves, even though most of them wouldn’t be able to speak for some months.

Babies understand basic physics
Human infants appear to arrive with prior expectations about how the world works. For example, a 2009 study found that 5-month-olds use basic cues to detect whether a material is solid or liquid, and having done so, they form expectations for how these substances will behave, such as whether they will pour or tumble, or whether they will be penetrated by a straw. “… these experiments begin to clarify the beginnings of naive physics,” the researchers said.

If you enjoyed this post, you might also like The Psychology of First Impressions, Digested.

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

Do infant dummies (pacifiers) impede the emotional connection between adult and baby?

Dummies (known as pacifiers in the US) can calm a crying baby in seconds, so their appeal is obvious. However, a new study warns there could be a price to pay. Magdalena Rychlowska and her colleagues claim that because dummies obscure babies’ faces, they interfere with the way that adults respond to babies’ emotions.

The researchers used electrodes to record the facial muscles of 29 women (average age 21; two of them were mothers) while they looked at photographs of two young babies expressing happiness, sadness, anger or a neutral emotion. Sometimes the babies had dummies in their mouths; other times didn’t. Also, some of the photos featured a white square superimposed over the baby’s mouth region. This last condition was to control for any influence of the sight of a dummy, beyond its obscuring effect. As well as having their facial activity recorded, the participants also rated the intensity of the emotions shown by the babies.

When the women looked at happy babies with a dummy in their mouth (or when a white square was superimposed over the babies’ mouth region) they exhibited less activity in their Zygomaticus muscle, which pulls the mouth into a smile. In other words, they showed less mirroring of the babies’ happiness. When the babies had a dummy, or a white square covered their mouth region, the women also rated the babies’ happiness to be less intense. The presence of a dummy was no more interfering than the white square, which suggests the effect of the dummy was purely due to its visually obscuring effect, not to any cultural or emotional assumptions the women may have made.

What about when the babies expressed sadness and anger? The women’s corrugator frowning muscles were just as active when they looked at sad and angry babies whether the babies had a dummy or not, and irrespective of the presence of a white square. However, the women rated the babies’ sadness as less intense when the babies had a dummy or when a white square was superimposed over their mouth area.

The researchers said their results are important because they show how the use of babies’ dummies can interfere with emotional resonance between adult and baby. “Resonance with adult perceivers allows to infants to gain emotional understanding and develop mentalizing abilities,” they said. They also noted: “…[P]erceivers may find interactions with infants using a pacifier less enjoyable and less stimulating.” The new results also build on past research by the same team, which found amount of dummy use in infancy was associated (in boys only) with less automatic facial mimicry at age 6 to 7. Bear in mind though, that this past research did not prove dummy use was responsible for the later reductions in mimicry.

There are some obvious problems with this new study – most obviously the reliance on static photographic stimuli, and also the fact that the research didn’t involve mothers or fathers interacting with their own offspring. It’s also worth highlighting that the use of infant dummies has been associated with positive outcomes, most notably reduced risk of sudden infant death when used during sleep. Some parents might also counter the current findings with the argument that, by soothing their babies’ distress, strategic use of dummies actually has emotional benefits for their babies.


Rychlowska, M., Korb, S., Brauer, M., Droit-Volet, S., Augustinova, M., Zinner, L., & Niedenthal, P. (2014). Pacifiers Disrupt Adults’ Responses to Infants’ Emotions Basic and Applied Social Psychology, 36 (4), 299-308 DOI: 10.1080/01973533.2014.915217

further reading
How infants affect how much their carers engage with them
Systematic evidence of fake crying by a baby
What makes a baby smile?

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

Psychologists use baby-cam to study infants’ exposure to faces

An infant sporting the baby-cam, worn upside down to ensure the camera
was level with the eyebrows. Image reproduced with permission of N. Sugden.

What does the world look like from a baby’s perspective? In the first research of its kind, psychologists in Canada have analysed hours of video footage taken from small cameras worn by babies on their heads. Nicole Sugden and her colleagues were particularly interested in the babies’ exposure to faces, to find out whether the kind of faces they were exposed to might explain a developmental process known as “perceptual narrowing”. In the context of face recognition, this is the finding that babies gradually lose their ability to distinguish between other-race faces and other-species faces.

The researchers recruited the parents of 14 1-month-olds and 16 3-month-olds. There was an even mix of girl and boy babies, and the families were of a variety of ethnic backgrounds including Caucasian, Southeast Asian, and Black-Caucasian. For a two-week period the parents were asked to place the smiley faced camera, attached to a headband, onto their baby’s head whenever he or she was awake.

In total, the researchers obtained nearly 20 hours of footage from the 1-month-olds and over 25 hours footage from the 3-month-olds. This difference reflects the fact that the older babies were awake an average of 9 hours a day, while the younger babies were awake an average of 7 hours daily. The footage was varied, taking in the home environment and outdoors, including situations where adults were playing with their babies but also many other contexts such as riding in a stroller, at parent groups, and out at a restaurant.

Sugden and her team found evidence the babies experienced “massive” exposure to faces, accounting for 25 per cent of their waking lives. They also found a dramatic bias towards babies being exposed to own-race faces – 96 per cent of all faces matched this category. This is despite the fact that the research was conducted in Toronto, a multicultural metropolitan city with a diverse population. The researchers said this overwhelming exposure to own-race faces could be responsible for the fact that by three-months of age, babies already show a preference for looking at own-race faces. By six months they are already starting to lose their ability to distinguish other-race faces.

The baby-cam footage also revealed that the babies were overwhelmingly exposed to female faces (accounting for 70 per cent of all face exposure) – which likely explains babies’ usual preference for female faces – and to adult-age faces (accounting for 81 per cent of all face exposure).

This research did not directly address whether the experiences of individual babies led to specific changes in their perceptual abilities and preferences. However, the findings are compatible with this idea. “This study is the first to document the quantity and quality of infants’ natural daily face exposure from the infants perspective,” the researchers said, “and offers strong support for the idea that experience drives the development of the face processing system.”


Sugden NA, Mohamed-Ali MI, and Moulson MC (2014). I spy with my little eye: Typical, daily exposure to faces documented from a first-person infant perspective. Developmental psychobiology, 56 (2), 249-61 PMID: 24285109

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

Systematic evidence of fake crying by a baby

Image: Tucia / Flickr

Crying is an important survival behaviour for babies – the world is informed that they are in distress and need prompt attention. Many parents also describe what looks like fake crying by their infants. It seems as though the child is pretending to be in distress merely as a way to get attention. Some people doubt that babies can really be capable of such deception, but now Hiroko Nakayama in Japan has published the results from six months’ intensive study of crying by two babies, and she reports persuasive evidence of fake crying by one of them.

Nakayama filmed the babies in their homes for sixty minutes twice a month, for six months. The videos were then carefully coded by two researchers in five-second segments. Sixty-eight episodes of crying were documented for Baby R, aged 7 months at the study start; and 34 episodes for Baby M, aged 9 months at the study start.

The analysis focused on the presence of positive and negative affect (emotion) in the minutes and seconds prior to and after episodes of crying. All of Baby M’s crying episodes were preceded by clear evidence of distress and negative affect, as betrayed by grimaces, vocalisations and downturned lips.

Just over 98 per cent of Baby R’s crying episodes were also preceded by negative affect, but there was a single instance at 11 months where her crying immediately followed positive emotion (indicated by smiling or laughing), and then positive emotion abruptly followed the bout of crying. The mother recognised this behaviour as fake crying, and the emotional analysis appeared to confirm this. “Infant R appeared to cry deliberately to get her mother’s attention,” said Nakayama, “[then] she showed smile immediately after her mother came closer.”

People might have a negative impression of “fake crying” said Nakayama, but they shouldn’t do. It attracts the attention of the care-giver, and “such individual interaction contributes greatly not only to an infant’s social development but also to their emotional development. Infants who are capable of fake crying might communicate successfully with their caregivers in this way on a daily basis. Fake crying could add much to their relationships.”

Another insight from this research included the finding that most of the time the babies’ crying was followed by continued negative affect. Positive affect only returned gradually with care-giver physical contact, or, in the case of Baby R, a combination of physical contact and eye contact.

It can only be speculation with such a small sample, but one possible reason for more frequent crying in Baby R, and her use of fake crying, is that she had two siblings, whereas Baby M was an only child. Baby R may therefore have needed to compete more for her mother’s attention. “Siblings can enrich social interactions at home and increase their variety,” said Nakayama. “Such environmental factors are known to stimulate the development of communication skills of infants.”


Nakayama H (2013). Changes in the affect of infants before and after episodes of crying. Infant behavior & development, 36 (4), 507-12 PMID: 23732624

further reading
Does crying really make you feel better?
Differences in the way teen and adult mothers respond to baby cries
Why do children hide by covering their eyes?

Christian Jarrett (@Psych_Writer) is Editor of BPS Research Digest

Nine-month-olds prefer looking at unattractive (read: normal) male bodies

When faces were hidden or schematic, 9-month-olds preferred looking at the “unattractive” male bodies

Out-of-shape new dads around the world take heart – your little munchkin thinks your fuller figure is nicer to look at than the ripped, six-pack-boasting torsos so often seen in magazines and after-shave adverts.

Michelle Delaney at the University of Sheffield and her colleagues presented dozens of babies with pictures of pairs of Caucasian male bodies wearing only underwear: one was always “unattractive” with a fuller waist and smaller chest; the other was always more muscular, with a V-shaped torso, a larger chest and narrower waist. “The men with attractive bodies were models, and the men with unattractive bodies were friends of the experimenters,” the researchers explained. It wasn’t stated whether these volunteers remained friends with the researchers after reading the descriptions used in the study.

Videos were taken of the babies’ eye gaze, and after they’d spent a total of ten seconds looking at one pair of pictures, a new pair was shown. The key test was whether the babies would choose to spend more time looking at the V-shaped “mesomorphic” male bodies (rated earlier as more attractive by hundreds of adult male and female participants) or at the less attractive, normal-shaped male bodies.

Nine-month-olds showed a clear preference for looking at the unattractive, normal male bodies, but only in versions of the experiment where the men’s faces were obscured. If the faces were shown, no body preference was found. This might simply be because of babies’ well-known attraction to faces, which may have distracted them from the bodies.

Babies aged 3.5 months and 6 months showed no preference for one male body type or the other. A habituation test (based around the idea of babies finding a new type of image interesting to look at) showed that 3.5-month-olds couldn’t tell the difference between the two body types. Six-month-olds could, but they didn’t show a preference.

Why should nine-month-olds prefer looking at cuddlier-shaped men? Delaney and her colleagues think the preference probably arises from what babies are used to encountering in their daily lives – after all, they said, a recent NHS survey in England found that “66 per cent of men were overweight or obese”. A related explanation is that the babies prefer female-looking bodies (perhaps because they see their mother more often), and male bodies with more fat have a closer resemblance to a female body.

The emergence of the babies’ preference for a particular male body type between 6 and 9 months complements past research suggesting that it is around the age of 9 months that babies typically begin to show a sophisticated recognition of the human form – for example, they are sensitive to the normal proportions of the arms, legs and neck.

 “The current study suggests that during infancy, preferences for particular human body shapes reflect level of exposure and resultant familiarity rather than culturally defined stereotypes of attractiveness,” the researchers said. “Precisely when and how children develop preferences for adult-defined attractive bodies remains a question for future research.” They added that it would be interesting to repeat the research to see if nine-month-olds’ preferences vary with the differing average body sizes across cultures – for example in Japan versus Samoa.


Heron-Delaney, M., Quinn, P., Lee, K., Slater, A., & Pascalis, O. (2013). Nine-month-old infants prefer unattractive bodies over attractive bodies. Journal of Experimental Child Psychology, 115 (1), 30-41 DOI: 10.1016/j.jecp.2012.12.008

Image reproduced with the permission of the first author.

–Further reading–
Lads’ mags and feelings of physical inadequacy – single men most at risk

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

At what age do babies enter the uncanny valley?

In the 1970s, the roboticist Masahiro Mori noticed a curious phenomenon. As robots became more human-like, their appeal increased but only up to a point. When their human likeness became too realistic (but still not perfect), their appeal plunged. Mori nicknamed this abrupt aversion “the uncanny valley“, in reference to the shape of the graph mapping human-likeness and appeal. Are we born with this aversion to the almost-real or does it emerge later?

To find out, David Lewkowicz and Asif Ghazanfar presented nearly a hundred infants (aged between 6 to 12 months) with pairs of faces, to see which they would look at for longer. In the first study, the babies were shown a human face alongside a cartoon face (an “avatar”) with enlarged goggle-eyes. The researchers said adults would find the avatar uncanny and would avoid looking at it. The key finding here was that six-month-olds spent more time looking at the uncanny avatar, whereas the twelve-month-olds, like adults, spent more time looking at the human face. Based on this dramatic contrast in preference, Lewkowicz and Ghazanfar said the uncanny valley effect emerges gradually between six and twelve months of age.

What was it about the faces that provoked this change in preference in the older babies? In two further studies, the researchers presented the babies with either a goggle-eyed uncanny avatar alongside a more realistic avatar face with normal-sized eyes, or with a human face alongside the realistic avatar. In the first case, all the babies, from 6 to 12 months, spent more time looking at the realistic avatar. In the second case, the babies of all ages spent equal amounts of time looking at the two faces.

These results suggest that none of the babies could distinguish between the realistic avatar and a real human face, and that the older babies in the first study, and all the babies in the second study, must therefore have been using the enlarged eyes to distinguish the goggle-eyed avatar from a human face or realistic avatar face, respectively.

Lewkowicz and Ghazanfar said that the aversion to the goggle-eyed uncanny avatar likely emerged in the older babies as a consequence of their growing expertise with processing human faces, and their association of human faces with positive consequences. However, the older babies’ expertise was obviously far from complete because they were unable to tell a realistic avatar from a human face. By 12 months, they can spot uncanny features, it seems, but not a synthetic face. “This limitation, particularly at the end of the first year of life, is interesting,” the researchers said, “because infants of this age have already become sufficiently specialised for human faces that they no longer discriminate the faces of other species and of other races [a process known as perceptual narrowing]”.

This study builds on recent research showing evidence of the uncanny valley effect in monkeys. From an evolutionary perspective, the researchers said their results were consistent with the idea that the uncanny valley effect emerges as a result of early developmental experience and was “a useful behavioural adaptation because it enables observers to quickly detect anomalies (e.g. disease) and/or aesthetic value (i.e. beauty) of a face.”

Critics of this research may feel that it is rather a leap to assume that the uncanny feeling experienced by adults is felt by babies in any way, just because they look at a face more or less. Moreover, the classic uncanny valley effect is about almost-real robots and faces. This study arguably complicates the issue somewhat by introducing specific abnormal features onto synthetic faces, therefore making them look unreal. Whilst it’s been shown that abnormal features, such as enlarged eyes, are perceived as uncanny by adults, this could be a different effect from the discomfort caused by not-quite-perfect hyper-realistic entities.


Lewkowicz, D., and Ghazanfar, A. (2012). The development of the uncanny valley in infants Developmental Psychobiology, 54 (2), 124-132 DOI: 10.1002/dev.20583

Post written by Christian Jarrett for the BPS Research Digest.