Babies sometimes overhear our heated arguments. Can babies tell when parents are fighting? Or does it go over their heads?
Experimental research confirms that babies can sense when their mothers are distressed, and the stress is contagious.
Experiments also show that 6-month old infants become more physiologically reactive to stressful situations after looking at angry faces (Moore 2009).
So it's likely that babies can tell when their parents are embroiled in a nasty argument, and no, it doesn't go over their heads. On the contrary. They feel our stress.
How might this stress affect babies?
It can be hard to tell what's going on inside an infant. They can't tell us in words, and they don't always provide us with easy-to-read signals. For example, babies can experience physiological stress and remain relatively quiet.
So in addition to monitoring behavioral signs, researchers use physiological measures.
One common method is to place an electrode on a baby's chest and measure subtle variations in his heart rate as he breathes.
This variability is called respiratory sinus arrhythmia (RSA), and it offers us a window in the baby's parasympathetic nervous system -- the system that helps us relax and recover from stress.
What do studies of RSA tell us? Unfortunately, they confirm our worries.
Babies exposed to lots of family conflict show RSA patterns typical of people with stress disorders and emotional problems (Mammen et al 2017; Porter and Dyer 2017; Moore 2010).
Their parasympathetic nervous systems seem to have more trouble calming down, and that could lead to behavioral, emotional, and health problems down the road.
Then there is the picture provided by brain scan studies. Could the stress of witnessing parent conflicts alter the development of an infant's brain? It seems likely. Here are the details.
Alice Graham and her colleagues wanted to know if babies' brains respond differently to emotional stimuli depending on how much their parents argue. So the team recruited 20 couples with babies between the ages of 6 and 12 months, and asked the mothers to rate how often and intensely they fought with their domestic partners.
Then the researchers scanned the infants' brains using functional magnetic resonance imaging (fMRI).
It's important to keep physical movement to a minimum during an fMRI scan, so the babies were scanned as they slept. And during the scan -- while the infants remained asleep -- they heard a series of audio recordings.
Each recording featured the voice of a man speaking a series of nonsense words. But the man's emotional tone varied from one recording to the next. Sometimes he sounded happy. On other occasions, he sounded mildly angry. Or very angry. Or emotionally neutral.
How did the babies’ brains respond to these sounds? As you might expect, it depended on the particular emotion being expressed. For example, the happy voice stimulated heightened activity in different parts of the brain than the angry voice did. And that was true for all babies, regardless of how much conflict their mothers reported in the home.
But when the researchers compared the very angry voice with the neutral voice, they discovered a telling pattern. The more conflict a mother reported in the home, the more reactive her baby’s brain was to the very angry voice.
Babies from high-conflict homes experienced a pronounced spike in activity in the rostral anterior cortex, a region associated with the processing of emotion, and one that is frequently altered among people suffering from stress disorders.
They also experienced heightened activity in more primitive parts of the brain, including the hypothalamus, a structure that controls and directs the stress response.
So the brains of the babies from high-conflict families were indeed different. They were especially reactive to angry voices -- in brain regions that process stress and emotion.
Might such babies also show differences in the way that distinct brain regions communicate with each other?
That's an important question, because we know that people experiencing mental health problems often show atypical patterns of brain connectivity.
For example, there is evidence that adolescents diagnosed with major depression experience greater connectivity between the posterior cingulate cortex (PCC) and another brain region, the anterior medial prefrontal cortex (Ho et al 2015).
So in a second study, the investigators looked for this pattern, and they found it: Babies from high-conflict homes showed greater connectivity between these same brain areas (Graham et al 2015).
The results are worrying, especially in light of what we know about early life stress in general: It puts babies at higher risk for developing emotion problems and stress-related disease. Maybe these studies offer a window on how it all begins.
But can we conclude that these brain differences are caused by overhearing angry arguments at home? Maybe something else is to blame.
The researchers addressed some alternative explanations. For instance, in the second study they controlled for the effects of prenatal stress, which by itself can have a big impact on brain development.
In addition, the researchers did a background check on the participating families, and found no evidence that there was a history of physical abuse.
But the researchers didn't control for genetic factors, which are surely part of the story. And these are just two, small studies. They need to be replicated.
Nonetheless, I think we have good reason to assume that frequent parent conflicts can influence the course of infant brain development. Extensive experiments on rodents -- which control for genetics -- demonstrate that social stressors can alter an infant's brain and stress response system.
And if nothing else, these fMRI studies tell us that some babies' brains are especially reactive to the sound of anger. Even if this special sensitivity was caused by something else, we'd still have to contend with the fact that family conflict is going to trigger hyper-reactive stress responses in these infants.
From a practical standpoint, the takeaway is the same: We need to protect babies from overhearing angry arguments and fights.
This research should be a wake-up call to parents -- not a message of hopelessness for families that have experienced conflict in the past.
If your baby has been exposed to stressful conditions -- before or after birth -- you shouldn't feel your baby has been irreparably damaged. Far from it. Babies can be very resilient -- if we offer them the right support.
For example, research suggests that frequent, affectionate touch can reverse the effects of prenatal stress in young infants (Sharp et al 2012; Pickles et al 2017). It may help counteract postnatal stress as well.
In addition, warm, sensitive, responsive parenting appears to buffer kids from the negative effects of growing up in stressful environments.
And highly reactive, stressed-out babies have the potential to become extremely well-adjusted kids -- if their parents are patient, sensitive, and emotionally responsive.
Check out these links, as well as my articles, “Stress in babies: How to keep babies calm, happy, and emotionally healthy,” and “Difficult babies can become super kids.”
For more information about coping with your own stresses, see
Graham AM, Fisher PA, Pfeifer JH. 2013. What sleeping babies hear: a functional MRI study of interparental conflict and infants' emotion processing. Psychol Sci. 24(5):782-9.
Graham AM, Pfeifer JH, Fisher PA, Carpenter S, Fair DA. 2015. Early life stress is associated with default system integrity and emotionality during infancy. J Child Psychol Psychiatry. 56(11):1212-22.
Ho TC, Connolly CG, Henje Blom E, LeWinn KZ, Strigo IA, Paulus MP, Frank G, Max JE, Wu J, Chan M, Tapert SF, Simmons AN, Yang TT. 2015. Emotion-Dependent Functional Connectivity of the Default Mode Network in Adolescent Depression. Biol Psychiatry 78(9):635-46.
Mammen MA, Busuito A, Moore GA, Quigley KM, Doheny KK. 2017. Physiological functioning moderates infants' sensory sensitivity in higher conflict families. Dev Psychobiol. 59(5):628-638.
Moore GA. 2009. Infants' and mothers' vagal reactivity in response to anger. J Child Psychol Psychiatry. 50(11):1392-400.
Moore GA. 2010. Parent conflict predicts infants' vagal regulation in social interaction. Dev Psychopathol. 22(1):23-33.
Pickles A, Sharp H, Hellier J, Hill J. 2017. Prenatal anxiety, maternal stroking in infancy, and symptoms of emotional and behavioral disorders at 3.5 years. Eur Child Adolesc Psychiatry. 26(3):325-334.
Porter CL, Dyer WJ. 2017. Does marital conflict predict infants' physiological regulation? A short-term prospective study. J Fam Psychol. 31(4):475-484.
Sharp H, Pickles A, Meaney M, Marshall K, Tibu F, Hill J. 2012. Frequency of Infant Stroking Reported by Mothers Moderates the Effect of Prenatal Depression on Infant Behavioural and Physiological Outcomes. PLoS ONE 7(10): e45446.
Content of "Can babies tell when parents are fighting?" last modified 7/30/2018
image of baby by Jim Champion/flickr
image of adults arguing by Vic/flickr