r/science • u/mvea Professor | Medicine • 1d ago
Neuroscience Pandemic-era children show altered brain responses to facial expressions, with a reduced neural response to happy faces. One possible explanation is that happy expressions may have decreased during the pandemic, due to both mask-wearing and the emotional toll experienced by caregivers.
https://www.psypost.org/pandemic-era-children-show-altered-brain-responses-to-facial-expressions-new-study-finds/207
u/AcanthisittaSuch7001 1d ago
This study is messed up in my opinion
Nowhere in the study do they report what would be the expected rate that healthy normally developing children should be able to identify happy or fearful faces
They don’t actually report the actual numbers / percentages of how many pre-COVID kids could reliably react (neurologically based on EEG response) to happy or fearful faces. And they don’t report what the percentage difference in this reactivity is in COVID-era children versus pre-COVID children
Without this critical data, it is very difficult for me to makes heads or tails out of these findings
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u/yummychummy 1d ago
I'm a bit confused by your comment. They address the fact that this is not a behavioral test, and that they are studying only neural processing. They do frame the importance of neural processing in theories of social development. I have a feeling we both are similarly disinterested in ERP data that isn't complimented by behavioral data, but I don't know why you feel the study is 'messed up'.
I'm not sure what you would gain from having the individual data/raw numbers. You can see that there is relatively little variance in their data, suggesting relative uniformity of neural activity in each group.
I'm no expert in ERP, but how would knowing the magnitude of the difference help you make heads or tails of the findings? Is there some percentage difference that consistently predicts behavioral changes for example?
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u/AcanthisittaSuch7001 1d ago
In order to know if the rate to which the children of the study respond neurologically/EEG-wise to happy faces is abnormal or pathological, we need to know what the “normal” rate of how often children would respond in this way to seeing happy faces across a diverse, representative sample of children.
The implication of the study is that the children were somehow stunted in their development by COVID era masking and social isolation. But it’s impossible to say that is the case if we don’t have baseline data on what is a normal percent of the time children would respond neurologically to happy faces. The authors don’t provide this data, nor do they provide the actual percent of the time the children in the study respond “appropriately” neurologically to happy faces. Unless I am missing the days somewhere. Let me know if you are seeing something different.
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u/yummychummy 1d ago edited 1d ago
The control 'pre-covid' group is a different group of children that were tested pre-covid. They are the "normal" representative sample. It's not super clear from their wording, you would need to go into the supplemental methods for their population selection.
As for percent differences for data like this, there is a lot of noise. Any single trial is not very informative. It's like trying to hear a whisper (event-related neural electricity) in a noisy bar (electrical noise from the atmosphere and equipment). It takes the data from many trials averaged to generate a reliable trace of neural activity. By running many trials they can get the same whispers repeated each time, but the conversations in the bar change and their contribution to the overall signal diminishes. In other words, whether any single trace of neural activity for a single trial is higher or lower than pre-covid controls is not meaningful, as single trial waveforms are too noisy. Only by averaging traces over many trials can the signal rise above noise enough for meaningful comparisons to be made.
They don't report differences as percentage of trials where one trace was different than control, but they do show proportional differences in the normalized data. But as I'm not an expert in ERP the effect size of these proportional differences aren't very meaningful to me. Even if one was two hundred times larger than the other, I wouldn't really know what that means in the context of this type of data. That's why I was asking if there was some proportional difference that would be convincing for you.
However, the statistics are clear that it is very unlikely they would find ERP differences of that magnitude by chance alone.
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u/AcanthisittaSuch7001 1d ago
I don’t even know what magnitude of difference I would find compelling ha. Especially without knowing baseline levels of ERP in healthy children exposed to happy faces.
I just feel like this study is casting aspersions on COVID era policy and making parents feel like we have somehow ruined our children by messing up their ability to process emotion. And I really don’t think that take away is earned at all by the findings. It seems like a very preliminary and speculative study at best.
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u/yummychummy 1d ago edited 1d ago
Again, they do show the baseline levels of ERP in children that were tested before COVID happened (figure 3). I think based on the responses that there a lot of parents feeling attacked in this thread. However, the researchers are quite cautious about making any predictions about children's future social behavior based on the ERP data. In fact, this whole study is just a small off-shoot of a much larger study that is also looking at behavioral changes in children all the way up to teenagers.
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u/AcanthisittaSuch7001 1d ago
I don’t agree with your analysis
Here is the Figure 3 in question:
Looking at the graph, all that we can take away from this is that the mean ERP amplitude for processing emotional faces is somewhat slightly blunted for the COVID group. However, it is NOT established here that the slightly lower amplitude in the COVID group represents a pathologically low amplitude.
These graph are only showing mean / average data. For the pre-COVID data, we would need to see all of the amplitudes for all the children studied. Then we could perhaps say the lowest 5% amplitude of the pre-COVID children represents “abnormally” low facial emotional processing. Then if the COVID era kids facial processing was below this 5th percentile cutoff, that would be compelling. However we have no idea what the cutoff for pathology would be, or if the blunted amplitude in the COVID era children dips below such a pathological threshold.
Of course even such a 5th percentile cutoff would be arbitrary. The gold standard would be identifying children with significant clinically diagnosed developmental / emotional processing issues and then showing they these children have ERP amplitudes blunted or a certain level. Then if a larger percentage of COVID era 3 year olds had ERP amplitudes below that level, that would be very compelling.
There is no evidence that the slight ERP amplitude blunting in the COVID era children in this study is pathological or clinically meaningful in any way. They have not provided any data or evidence to support such a claim
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u/yummychummy 16h ago
I didn't provide any analysis for you to disagree with. I just said that figure 3 shows what you said was missing: baseline data from healthy children.
I think you've set up a bit of a strawman argument about pathology. I didn't say anything about pathologically low amplitudes, neither do the authors. The authors also never say that these differences in ERP would drive clinically diagnosable changes in social behavior. In fact, diagnosable social issues were one of the exclusion criteria (they disallowed those children from participating).
Actually, now that you've looked at figure 3, you've come to more or less the same conclusion as the authors which is that "the mean ERP amplitude for processing emotional faces is somewhat slightly blunted for the COVID group". Although they just say the ERP amplitude was blunted, instead of 'somewhat slightly blunted'.
I understand that parents are interested in what the observable change to children's behavior may be, and how this data may predict or underlie those changes. However, that's not what this study was for.
So if you're having a hard time seeing how they proved that these neural differences will change the children's behavior that makes sense, because that's not what they're trying to prove. However, your original comment says you can't believe the findings because they don't provide data from 'healthy controls', which isn't true.
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u/AcanthisittaSuch7001 15h ago
Well they didn’t provide meaningful data. An average of the amplitude is not really helpful. I need to see the whole bell curve, to see what the distribution of the amplitudes are. That would be much more helpful.
But yes I agree, the data are not clinically meaningful. At best this study sets up a hypothesis that can be tested further in future studies.
I think the study is written in a bit of an unclear way, and I think people were having a hard time understanding the results, which is understandable.
I just didn’t want people in this thread to think that this study was showing that COVID era policies and masking/social distancing harmed children’s brain function / emotional processing. This study does not show that in any way
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u/yummychummy 15h ago
Ah, now that you see the point of the paper, and that they did provide a non-covid control group, would you agree that the data provided was appropriate to support the conclusion that covid era-policies altered neural processing of facial emotion?
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u/loggic 1d ago
This study demonstrates the same problem as so many others: they're studying something related to pandemic policies, but never even attempt to consider whether it is an impact of the disease vs the policies they're assuming are at fault. They simply assumed the children had reduced exposure to facial expressions and assumed that infection was not related to anything they measured.
They compared a set of samples from before the pandemic to a set of samples during the pandemic and found a difference. Considering the well-documented impact COVID can have on the brain, even among those with seemingly mild symptoms, it is a colossal error to simply ignore it when attempting to understand the data.
Before this study can make any kind of useful statements about the impacts of policy choices, it needs to attempt to control for whether the tested children had been infected or not and needs to at least ask about the social impacts these children actually experienced.
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u/yummychummy 1d ago
That would be interesting if illness could change ERP data particularly in children. Are there many examples of the flu changing ERP data? I know COVID impacts the brain but I thought ERP was fairly hardwired and would require some severe brain damage to change.
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u/Das_Mime 15h ago
I know COVID impacts the brain but I thought ERP was fairly hardwired and would require some severe brain damage to change.
I'm not clear on why you think that some aspects of the brain are "hardwired" and can only be altered by "severe" brain damage. Long covid is, for example, known to significantly affect taste and smell, in severe cases even causing total loss of those sensations or drastic alterations (so that food tastes like sewage, for example). Given those facts, why would it be surprising for it to have a mild effect on the neurological response to visual stimuli?
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u/yummychummy 14h ago
The long-lasting loss of smell caused by covid has been attributed to damage to olfactory receptors, not necessarily the brain regions that impact our perception of smell. If I was familiar with cases of COVID-induced face blindness then I would certainly be singing a different tune.
ERPs are generated by many millions of neurons firing in specific patterns, and my assumption is that a very drastic insult would be necessary to drive even a small change in the activity of so many cells. I have only heard of differences in ERPs being driven by differences in development, and hadn't heard of studies showing that any type of flu had a long-lasting impact on any type of ERP data. Someone did point out that HIV impacts ERPs, but have you seen examples of less severe illness causing long-lasting changes in ERPs to visual stimuli?
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u/Das_Mime 10h ago
ERPs are generated by many millions of neurons firing in specific patterns
So are quite a lot of cognitive functions and long covid is well known to cause brain fog, which is a catchall for a variety of cognitive dysfunctions, so it certainly can affect such processes
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u/loggic 13h ago
Here is a study comparing ERP data among 3 groups: Long COVID vs Mild Cognitive Impairment vs control.
The authors of this study also discussed your point in another comment about changes in the sense of smell:
Cognitive and olfactory impairments have a strong negative effect on patients’ quality of life, regardless of whether they are caused by a virus or the onset of a neurodegenerative disease. Anyway, MCI and LC could share common or similar pathophysiological, psychophysiological, and neuropsychological mechanisms. COVID-19 attacks the central nervous system (CNS), causing chemo-sensory deficits such as anosmia, encephalitis, cerebrovascular disorders, or brain fog [4,5]. In more detail, the SARS-CoV-2 virus directly invades the CNS due to the interaction between the SARS-CoV-2 spike protein and angiotensin-converting enzyme 2 (ACE-2), which is mostly expressed on neurons in the temporal lobe and hippocampus. Since these brain areas are involved in the pathophysiology of Alzheimer’s disease (AD), SARS-CoV-2 could accelerate the development of neurodegenerative disorders and potentially induce a worsening cognitive decline in MCI and AD patients [6,7,8,9]. Moreover, magnetic resonance imaging performed before and after COVID-19 infection has shown significant changes in experimental subjects’ brain structure compared to controls [10]. In particular, it seems that COVID-19 can cause a reduction in gray matter thickness in the orbitofrontal cortex and the parahippocampal gyrus and increased injury signs in brain areas that are functionally related to the primary olfactory cortex [11].
There are multiple ways that COVID can impact the sense of smell, including damage to the olfactory nerves, but that is certainly not the only way the sense of smell is impacted.
I am not aware of studies showing the flu having the ability to impact the central nervous system at anywhere close to the same extent as COVID, so I wouldn't expect there to be similar data. COVID is much worse than the flu in this regard, so relying on the flu to be some sort of parallel is not appropriate.
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u/yummychummy 11h ago
I appreciate you finding this paper to provide an example of covid-induced changes in ERP, but this one is a bit unusual in that it is specifically measuring neural activity in response to smells/olfactory stimulation.
I'm not saying the flu is the only or best comparator, just looking for some disease we've had more time to study (with less severe pathology than HIV). Sometimes flu can be quite severe and cause encephalitis.
The original comment and your initial response to me say 'why assume no impact of covid on ERP?', but I think it's more reasonable to be skeptical than to assume there is some impact of covid on ERPs to visual stimuli without a scientific consensus supporting it. They still haven't even come to a consensus on how or if HIV impacts ERPs to visual stimuli after thirty years of studying it.
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u/Supercc 1d ago
Probably cause they've been glued to their devices 24/7 that they're now jaded af
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u/dribanlycan 1d ago
maybe its from how video creators are always smiling in a vaugely wrong forced way? compounded with the constant exposure to such content
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u/Chemical_Shallot_575 1d ago edited 1d ago
Too many potential confounds here. As a researcher in the field, these would be considerations guiding my reading—
I’m presuming the participants were shown images/videos vs. naturally-elicited and reciprocal expressions. There are differences in ways infants react to these different contexts/stimuli.
Pandemic parents weren’t masking in the home. Especially with their infants. If anything, they were home more often with their children.
During the pandemic, children/infants might have been more likely to see direct (and reciprocal) facial expressions from family members and friends via FaceTime/video chat.
There has been a longstanding debate in infancy research regarding looking behavior and what it means. Children may look more due to novelty or due to preference.
(I could go on, but I’m sure others have similar ideas).
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u/yummychummy 1d ago
What type of research do you do? This paper isn't in my field but I'm finding more scientists responding to it than usual and with some strong opinions that fascinate me.
I don't really see that you've listed any confounds of the study. Confounds are issues with study design that make the data uninterpretable, but it doesn't seem like you read the methods if you don't know what the children were looking at.
I think your point that children saw a lot of parents faces during the pandemic makes sense. Maybe parents were happy to be home during the day with their children and that's why children had a lower amplitude response to smiling faces, because they saw them more often than the pre-covid control children.
What do you think about the discussion of the paper where they address the difficulty in interpreting the cause and effect of ERP differences? Overall I'd say they have pretty tame statements to make about the causes of their findings but again it isn't my field so I could use some help.
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u/Chemical_Shallot_575 1d ago edited 1d ago
“The current study aimed to investigate the effect of reduced variety of input…”
The entire purpose of this study was based on an empirically unsupported assumption.
I’m very familiar with this field and larger topic area. It overlaps with my own.
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u/yummychummy 16h ago
I don't think you read the paper before you commented that there were 'too many confounds'. My guess is you've gone to look it at after my comment but only to help support your pre-decided distaste for it.
It feels like you are picking and choosing sentences to make it seem that the researchers are oblivious to the challenges of collecting this type of data. They are fairly cautious in their explanation of why they feel there was a reduced variety of facial input in the introduction. They also explain that children may be seeing their immediate family more, which is exactly one of the 'confounds' you pointed out in your original comment.
The last sentence of the discussion is "Together, the current study reveals a difference in face processing between children tested before versus during the Covid-19 related policies. These group differences are interpreted as due to a reduced variety of facial input, but might be more specifically explained by for instance indirect effects of the policies." The researchers share your opinion that there are many factors involved.
While the researchers do contextualize their findings in the context of 'reduced variety of facial input', that's not the 'entire purpose of the study'. This is just a small part of a larger study tracking the development of youth in the Netherlands. The important data provided by the study are the differences in neural activity in children that were developing during the implementation of COVID policies.
Overall, and particularly in the Netherlands, there was a society-wide decrease in the likelihood of seeing stranger's faces. I agree that it would be great if they could quantify the exact number and type of facial input that children received, and that would strengthen their findings if it correlated with changes in neural activity. However, that doesn't really seem feasible. They think that reduced facial input is the most likely cause of neural differences and give support from the literature from why that would be important, but they provide other possibilities.
I'm not in the field of course and maybe you have some deep knowledge of how much more important other covid-19 policy-linked changes in social interaction are much more likely to drive changes in ERP than reduced facial input. However, you didn't provide any alternative explanation that wasn't also provided by the authors in the paper. I worry that comments like yours from experts may lead non-scientist redditors to think the paper is valueless.
Would you say the data is valueless? If not, what would you say the value of the data is?
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u/TSMO_Triforce 1d ago
Thats a weird explaination. If happy expressions became less common, shouldnt children have a stronger response to them when they actually do see them?
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u/palsh7 1d ago
So you're saying that kids who watched a ton of streaming content with unmasked people being emotional and making a variety of faces nevertheless lost the ability to differentiate faces? I'm not buying it. Sounds like ridiculous anti-Fauci propaganda.
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u/Ekyou 1d ago
Not to mention like… pretty much no one wears a mask at home 24/7. The only time my pandemic baby saw masks was at the doctor and the one or two grocery trips where we brought him along.
This isn’t the first study to show this, so there must be something to it. And I could believe kids who went to daycare every day might be affected… but young children at home likely barely ever saw a mask.
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u/greenplastic22 17h ago
Yes, this argument always seems strange to me. KIds were home with parents and siblings who weren't masked, watching streaming content where no one was wearing masks, and attending daycare without masks - maybe the daycare providers were masked for some parts of the pandemic, but if the kids were playing outside, the adults probably weren't masked in those situations. Families were also still having small gatherings, unmasked, in their "bubbles."
I know every place responded a little differently. I'm just speaking to what I saw. We were staying with my in-laws to save up for a move, and my MIL ran a daycare with two staff members and I think about 12 kids. I helped her with reviewing the government policy guidance and requirements so that's why I was more steeped in the rules for her situation.
It's just always odd to me because I never witnessed any kids as cut off and isolated from faces as what's implied.
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u/snow-mammal 1d ago
To me it sounds like it’s less about masking (why are only positive expressions impacted?) and more about the stress adults were under at the time.
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u/kissedbythevoid1972 1d ago edited 1d ago
This is a bit of a ridiculous comment. It was published by a developmental psychology journal; to deny the pandemic had an effect on child development is more anti science than whatever you’re trying to portray. Fauci responded to a pandemic, however the toll on society that a pandemic brings should be studied
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u/palsh7 1d ago
It doesn't stand to reason. No one wore masks on TV, no one wore masks at home, no one wore masks on Zoom, etc., etc. There's no way the pandemic had the effect they're claiming. Are you going to sit here and pretend that psychology journals have never made massive blunders that aren't replicable?
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u/Baud_Olofsson 21h ago
Ah yes, those perfidious Dutch, always busy spreading "anti-Fauci propaganda"...
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u/North_Hawk958 1d ago
Orrrrrr, it could be the virus which affects brains.
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u/yummychummy 1d ago
That would be interesting if illness could change ERP data particularly in children. Are there many examples of the flu changing ERP data? I know COVID impacts the brain but I thought ERP was fairly hardwired and would require some severe brain damage to change.
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u/North_Hawk958 1d ago
Not sure but there are millions of people/kids suffering with long covid and many of the problems are neurological. I’m one of them(adult) unfortunately. The way it changed how I was for the first year + was astonishing and terrifying. Looking back it’s almost like a whole other person occupied my body. It wouldn’t seem out of place if there are neurological changes to these children as well if they contracted SARS2 during that time period. Hopefully we’ll someday find out definitely what types.
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u/yummychummy 1d ago
I understand the assumption that since ERP is a measurement of brain activity, and covid causes neurological problems, that maybe ERP would change too. However, I can't find any published evidence that any contagious disease impacts ERP, maybe because the sensitivity of ERP is limited and the pathways it can measure are not sensitive to inflammation.
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u/North_Hawk958 1d ago
HIV is one that can I believe. I’m not sure how long it took to find that out though or how often it’s studied in other contagions. If Covid is having such an impact on long term neurological symptoms I’d hope it too would be studied and we’d find out faster than it took us to take HIV seriously. We’re only two years or so out of the emergency phase of the pandemic.
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u/yummychummy 1d ago
Ah that's interesting about HIV! It does seem like some moderate changes in ERP have been found there! Although, they've been working on whether and what type of changes in ERP are found in patients with HIV for thirty years so my guess is that it is a pretty subtle effect.
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u/mvea Professor | Medicine 1d ago
I’ve linked to the news release in the post above. In this comment, for those interested, here’s the link to the peer reviewed journal article:
https://www.sciencedirect.com/science/article/pii/S1878929325000015
Abstract
In response to Covid-19, western governments introduced policies that likely resulted in a reduced variety of facial input. This study investigated how this affected neural representations of face processing: speed of face processing; face categorization (differentiating faces from houses); and emotional face processing (differentiating happy, fearful, and neutral expressions), in infants (five or ten months old) and children (three years old). We compared participants tested before (total N = 462) versus during (total N = 473) the pandemic-related policies, and used electroencephalography to record brain activity. Event Related Potentials showed faster face processing in three-year-olds but not in infants during the policies. However, there were no meaningful differences between the two Covid-groups regarding face categorization, indicating that this fundamental process is resilient despite the reduced variety of input. In contrast, the processing of facial emotions was affected: across ages, while pre-pandemic children showed differential activity, during-pandemic children did not neurocognitively differentiate between happy and fearful expressions. This effect was primarily attributed to a reduced amplitude in response to happy faces. Given that these findings were present only in the later neural components (P400 and Nc), this suggests that post-pandemic children have a reduced familiarity or attention towards happy facial expressions.
From the linked article:
Pandemic-era children show altered brain responses to facial expressions, new study finds
A large study published in Developmental Cognitive Neuroscience has found that children who were tested during the COVID-19 pandemic showed measurable differences in how their brains processed faces, especially emotional expressions. While some aspects of face perception remained stable, the research found that three-year-olds processed faces faster and, across all age groups, children had reduced neural responses to happy faces, suggesting changes in how familiar or attention-grabbing these expressions were.
When it came to how quickly the brain responded to faces, the researchers found no meaningful differences in 5- or 10-month-old infants between those tested before and during the pandemic. However, in three-year-olds, there was a notable difference. Children tested during the pandemic showed earlier N290 responses to faces than their pre-pandemic counterparts, indicating faster neural processing of facial information. This was specific to faces and not observed when children looked at images of houses.
The finding of faster face processing was somewhat unexpected. In typical development, the speed at which the brain processes faces increases with age and experience. However, some previous research in adults has shown that reduced facial information — such as when faces are masked — can lead to quicker processing.
However, the most striking differences emerged when the researchers examined how children responded to emotional expressions. Children tested before the pandemic showed distinct patterns of brain activity when viewing happy, fearful, and neutral faces. But among those tested during the pandemic, this differentiation was reduced or absent.
In both ten-month-olds and three-year-olds, brain responses to happy and fearful faces became less distinguishable, especially in the later ERP components, the P400 and Nc, which are thought to reflect attention or familiarity.
These differences were particularly driven by a reduced neural response to happy faces. While children in the pre-pandemic group showed stronger brain responses to happy expressions, those tested during the pandemic had weaker responses. This pattern suggests that happy faces were either less familiar or attracted less attention in the post-pandemic group.
The researchers propose several possible explanations. One is that the variety of happy expressions that children saw may have decreased during the pandemic, due to both mask-wearing and the emotional toll experienced by caregivers.
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u/Wise-Field-7353 1d ago
Interesting... I saw one about how pandemic-era kids also suffered with theory of mind recently. Wonder if they're related.
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u/gameoflifeGenX 1d ago
It can’t be any different than these mom’s and dad’s with their heads in their phones 24/7 instead of interacting with their child. They should be studying how the iPhone destroyed the home environment. People are simply not communicating anymore.
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u/Grimaceisbaby 1d ago
It’s always anything but a virus.
Serious question, how can psych research be ethically done when we haven’t figured out the human body? It completely stopped research of conditions like ME/CFS for years. Why do we keep repeating this mistake?
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u/Baud_Olofsson 21h ago
Yet another pandemic study flailing at conclusions that could have been answered by comparing lockdown/non-lockdown and masking/non-masking countries...
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u/Far_Construction7986 1d ago
Okay now do homeschooled children that were homeschooled at a young age between 1st-4th grade
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