Abbreviated Science Round-up: ADHD and screen time, Nobels NOT so male, rewriting research rules

Child Development

PNAS: Does early exposure to electronic media contribute to ADHD?

Attention deficit hyperactivity disorder (ADHD) is now among the most commonly diagnosed chronic psychological dysfunctions of childhood. By varying estimates, it has increased by 30% in the past 20 years. Environmental factors that might explain this increase have been explored. One such factor may be audiovisual media exposure during early childhood. Observational studies in humans have linked exposure to fast-paced television in the first 3 years of life with subsequent attentional deficits in later childhood.

Up to that point, this paper has me nodding. And then …

As experimental studies in humans are neither ethical nor practical, mouse models of excessive sensory stimulation (ESS) during childhood, akin to the enrichment studies that have previously shown benefits of stimulation in rodents, have been developed.

First, I’m skeptical of the mouse / rat model in anything but very basic biochemistry. The “it works in rats” or “it’s bad for rats” track record is somewhere between “not great” and “almost worthless” depending on whether you’re testing a mechanism that operates on systems common and well-nigh identical across all mammals, or something where there’s wide divergence between primates and rodents. It’s hard to think of an area where there’s more divergence than in cognition. Also, rat / mice models of behavior have been used to justify some truly misleading “results” about behavior of individuals and groups. So count me triply skeptical.

Experimental studies using this model have corroborated that ESS leads to cognitive and behavioral deficits, some of which may be potentially detrimental. 

Er … maybe. Now, please stop over stimulating the rats.

PNAS: Another look at the relationship between screen media use and ADHD

The diagnosis of attention-deficit/hyperactivity disorder (ADHD) among children and adolescents has increased considerably over the past decades. Scholars and health professionals alike have expressed concern about the role of screen media in the rise in ADHD diagnosis. However, the extent to which screen media use and ADHD are linked remains a point of debate. To understand the current state of the field and, ultimately, move the field forward, we provide a systematic review of the literature on the relationship between children and adolescents’ screen media use and ADHD-related behaviors (i.e., attention problems, hyperactivity, and impulsivity).

Note that this isn’t a new experiment, but is a survey of literature. Which could include studies like the screen stressed mice I was just griping about. In any case, it includes a number of studies.

Using the Differential Susceptibility to Media effects Model as a theoretical lens, we systematically organize the existing literature, identify potential shortcomings in this literature, and provide directions for future research. The available evidence suggests a statistically small relationship between media and ADHD-related behaviors.

I don’t understand this statistical model enough to endorse or deny it. But, assuming it makes sense, the relationship between looking at pixels and developing ADHD appears to be within the level of noise. Overall, I certainly don’t see anything that says “Rip that iPad away from your children.”

PNAS: Kids learn language better with playmates

The current study investigates the effect of the presence of peers on infant foreign-language phonetic learning from video. We utilized the same Mandarin-language videos used previously in passive learning experiments, but made the procedure an active learning environment by allowing infants to control the presentation of videos using a touch screen. Each touch of the screen initiated a 20-s clip of the Mandarin speaker talking about toys and books. Given that previous research on children’s learning from peers or in the presence of peers presents children with a task, the touchscreen paradigm gives infants an active learning task that nevertheless presents the same information as previous research. We manipulate the presence of peers by randomly assigning infants to an individual-learning condition or a paired-learning condition. Infants in the individual condition participated in all study sessions by themselves, whereas infants in the paired condition always participated with another infant.

The results here are genuinely interesting from both groups. First off, kids did pick up language from watching interactive videos that connected words with objects and actions. So … cool. And kids who watched those videos with a partner learned faster, so a social component also plays into language acquisition. Also cool.

PNAS: 4-year-olds vs adults in picking up things from quickly edited videos

To comprehend edited video, viewers must infer the meaning conveyed by successive video shots (i.e., continuous video segments separated by edit points, such as camera cuts). The central question here was whether comprehension-related top-down cognitive processes drive eye movements during sequential processing of video montage. Eye movements were recorded as 4 year olds and adults watched a video with the same constituent shots in either normal or random sequence. The key analyses compared eye movements to constituent shots when presented in normal order with those to the same shots presented in random order. The dependent variable was attentional synchrony or the extent to which viewers looked at the same location at the same time, indicating commonality of processing the video.

Get that? Take a series of short scenes, show them in sequence, and track how quickly the eyes move to the key objects of those scenes. Then compare results when the scenes are scrambled.

Results indicated that children were more scattered in their gaze locations than adults.

There’s some interesting in here that could actually be directly useful if you’re wondering how to move the camera around in a simulation or video game. Or if you’re editing the next season of WestWorld into ten million two second clips (which could be the plan). But in any case, it’s interesting. Children who were less familiar with what was going on in a narrative scanned around the whole scene. Adults were more likely to move right to the focus point. Which really seems like it would be heavily weighted by better “I know what comes next” skills among adults.

PNAS: Does playing violent video games lead to aggression?

This seems like one of those questions that people just can’t stop asking. As with the second ADHD paper this isn’t a new experiment, but a literature analysis — so it’s only as good as the studies that it consumed.

To clarify and quantify the influence of video game violence (VGV) on aggressive behavior, we conducted a metaanalysis of all prospective studies to date that assessed the relation between exposure to VGV and subsequent overt physical aggression. The search strategy identified 24 studies with over 17,000 participants and time lags ranging from 3 months to 4 years. The samples comprised various nationalities and ethnicities with mean ages from 9 to 19 years. For each study we obtained the standardized regression coefficient for the prospective effect of VGV on subsequent aggression, controlling for baseline aggression.

The VGV is the measure of how much violent video games a child was exposed to, and across the studies surveyed there did seem to be a, not huge, but certainly present, connection between high VGV and increased aggression. The most interesting result here may be that this correlation was clearest in white males. Other groups exposed to similar values of VGV did not display the same correlation.

Honestly, while my first inclination is to say “yeah, that figures,” my second is to suspect either the methodology or the study or something specific about the nature of the games involved. Because I do not believe there’s something intrinsically different about the brains of white males as opposed to, say, Hispanic males — for good or ill. That doesn’t invalidate the study. It just suggests that the VGV value alone isn’t the key.

PNAS: The minds of future multi-taskers

As someone whose brain runs, at best, half-tracked (seriously that trains game in Lumosity is utterly beyond my creaky one-thing-at-a-time abilities while my wife slams out a new record every time she tries it) this is fascinating to me.

While the literature is still sparse, and is marked by both convergent and divergent findings, the balance of evidence suggests that heavier media multitaskers exhibit poorer performance in a number of cognitive domains, relative to lighter media multitaskers (although many studies find no performance differences between groups). When evidence points to a relationship between media multitasking level and cognition, it is often on tasks that require or are influenced by fluctuations in sustained goal-directed attention. Given the real-world significance of such findings, further research is needed to uncover the mechanistic underpinnings of observed differences, to determine the direction of causality, to understand whether remediation efforts are needed and effective, and to determine how measurement heterogeneity relates to variable outcomes. Such efforts will ultimately inform decisions about how to minimize the potential costs and maximize the many benefits of our ever-evolving media landscape.

Ha! Go single-trackers. So what if all the make-believe people on my little multicolor trains are dying in horrible, horrible micro-crashes?

Nobel Prizes

Since I hammered the Prizes just last week for “Nobels so male,” I’m going outside of journal-land to celebrate this story.

New York Times: Third woman in history among winners of Nobel Prize in physics

The 2018 Nobel Prize in Physics was awarded on Tuesday to Arthur Ashkin of the United States, Gérard Mourou of France and Donna Strickland of Canada for harnessing one of the most ineffable aspects of nature, pure light, into a mighty microscopic force. Dr. Strickland, a self-described “laser jock,” is only the third woman to win the physics prize, for work she did as a graduate student with Dr. Mourou.

Science News: Fifth woman to win a Nobel Prize in chemistry among three winners

Frances Arnold of Caltech won for her method of creating customized enzymes for biofuels, environmentally friendly detergents and other products. She becomes the fifth woman to win the Nobel Prize in chemistry since it was first awarded in 1901. Gregory Winter of the University of Cambridge and George Smith of the University of Missouri in Columbia were recognized for their development and use of a technique called phage display. This molecule-manufacturing process can generate biomolecules for new drugs.

The chemistry win in particular is interesting to me, as I actually cited work by one of the winners (sadly not Frances Arnold) in The Evolution of Everything.


Science: A Neptune-sized moon around a giant planet is the first discovery of an ‘exomoon’

Exomoons are the natural satellites of planets orbiting stars outside our solar system, of which there are currently no confirmed examples. We present new observations of a candidate exomoon associated with Kepler-1625b using the Hubble Space Telescope to validate or refute the moon’s presence. We find evidence in favor of the moon hypothesis, based on timing deviations and a flux decrement from the star consistent with a large transiting exomoon. Self-consistent photodynamical modeling suggests that the planet is likely several Jupiter masses, while the exomoon has a mass and radius similar to Neptune. Since our inference is dominated by a single but highly precise Hubble epoch, we advocate for future monitoring of the system to check model predictions and confirm repetition of the moon-like signal.

PNAS: How fast is the universe expanding?

Happy astronomers are still in the afterglow of … well, the afterglow.

The siren sounded on August 17, 2017. Astronomers picked up a burst of gravitational waves from the collision of two neutron stars, an event that Daniel Holz had been dreaming about for more than a decade. “You write these papers, and it sounds like fantasy. The equations say this might happen, but it’s completely different when nature cooperates and lets you make the measurement,” says Holz, an astrophysicist at the University of Chicago’s Kavli Institute for Cosmological Physics (KICP). “It’s just too good. It’s ridiculous. It’s embarrassing. But there it is.”

The neutron star merger, named GW170817, gave Holz and his colleagues an entirely new way to measure how fast the universe is expanding. This method could settle a simmering dispute between the two established ways of measuring expansion, and it could mean rethinking the makeup of our universe—perhaps requiring new types of a subatomic particle or unexpected forms of dark matter or dark energy.

And the answer is …

The data from GW170817 give a distance to it of about 40 megaparsecs. By combining that with the redshift of its host galaxy, the LIGO team ends up with [an expansion factor] of about 70 kilometers per second per megaparsec. That is right in the middle of the Planck and SH0ES values and with error bars large enough to accommodate either.

So this lone siren does not settle the dispute. But it has narrowed the exotic physics options. In most Galileon models and in some other theories of dark energy gravitational waves don’t travel at the speed of light. But telescopes saw the light from the collision arrive at almost exactly the same time as LIGO saw the gravitational waves. Based on this observation, Zumalacárregui and his colleagues, as well as other teams, ruled out such models of dark energy.

I’m telling you, my proposal that both dark energy and dark matter are simply gravitation leaking across ‘branes of the multiverse looks better all the time! (thus endeth whacky amateur physics minute)

Science: Diving into Saturn’s rings

This is actually the cover article for another special section — one on papers based on data collected in the final passes NASA probe Cassini made before plunging into Saturn. I’m not going to cover all the articles in this group, but the thought and technology that went into this project was amazing. This is what those upright-apes can do when they put their minds, and their screens, to it.

To avoid accidental contamination of the moons with any Earth bacteria that might have hitched a ride on the spacecraft, mission planners decided that when Cassini ran out of fuel it would be deliberately crashed into Saturn. As fuel reserves ran low, the spacecraft embarked on a series of maneuvers that took it through previously unexplored regions and ended with its destruction.

The first phase was a series of 20 “ring-grazing” orbits in which Cassini passed near the outer edge of the rings. Then the trajectory was shifted to fly through the gap between the planet and the inner edge of the rings, a phase dubbed the “Grand Finale.” Cassini flew through this region 22 times, in various orientations designed to optimize the scientific measurements made by its numerous instruments. Finally, in 2017 Cassini dove into the planet itself at 35 km s−1, leading to the spacecraft’s fiery disintegration in the upper atmosphere.


Science: The rapid rise and fall of kangaroo teeth

The story has always been that Australian mammals as a group diversified rapidly, fell just as quickly, and diversified again as the island continent swung through periods of scarcity and plenty. But looking at kangaroo teeth seems to show that some groups went out on top.

The teeth of mammals display complex adaptations to diet and can thus provide a window into the environments of extinct species. Couzens and Prideaux used such a window to examine the expansion and diversification of kangaroos, Australia’s largest herbivores (see the Perspective by Polly). True kangaroos diversified not in response to drying in the Miocene, as suggested by molecular results, but rather as grasslands expanded during the Pliocene. Furthermore, the now-extinct short-faced kangaroos were not declining because of increases in aridity at the end of the Pleistocene but instead were experiencing an increase in dietary divergence.


Nature: ‘Community participation’ is just one factor that’s re-writing the rules of scientific research, and amplifying both the quality and use of results.

Valarie Blue Bird Jernigan knew she had to tweak some standard scientific practices when she started her latest research project. One of the first things to go was the usual concept of a control group — people who would not receive interventions to encourage healthy eating. That wouldn’t be fair to the people of the Osage Nation, a Native American people in northeastern Oklahoma.

Another concept to ditch was the idea that she was studying a group at all. Jernigan, a public-health researcher, who is Native American herself, has treated the Osage people as equal partners from the first day of the project. It took two years and seemingly endless rounds of community discussions to get the study off the ground, but Jernigan wouldn’t have had it any other way. This kind of research “isn’t just about proving your hypothesis”, she says. It’s more about improving people’s lives and, at the same time, helping them gain the skills to do science.

This is absolutely your Read This One assignment for the week.


As usual, this week’s image came from Andy Brunning at Compound Interest. Perk yourself some fresh brew, then visit Andy’s site for a larger, easier to read version.

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