Consumers increasingly use smartwatches and other wearable devices to measure their heart rates and rhythm during exercise and for overall health monitoring. However, those measurements may be less accurate in people with darker skin tones (肤色), according to a study.

The findings are based on a systematic review of 10 previously published studies involving a total of 469 participants. The study is the first to pool data from many studies to specifically examine how skin tones may affect the accuracy of heart data in wearables.

After screening 622 scientific papers, the researchers identified 10 studies that reported the heart rate and rhythm data for consumer wearable technology according to a participant’s skin tone. Of those studies, they found that heart rate measurements were significantly less accurate in darker-skinned individuals compared with either lighter-skinned individuals or measurements from proven devices, such as chest strap monitors or electrocardiograms (心电图). One study reported that although there was no difference in heart rate accuracy, wearable devices recorded significantly fewer data points for people with darker skin.

Most wearables detect the heart rate and rhythm by aiming a beam of light at the wrist and then detecting how much light is absorbed. Greater light absorption indicates a greater volume of blood flowing through the veins (静脉) under the skin. The study results suggest that this signaling process might not work well in darker skin that contains more melanin (黑色素), which absorbs light.

In addition to the rising use of wearables to monitor physical activity and sleep patterns, interest in the use of consumer wearables for medical research and even early detection of heart problems has increased in recent years.

The study emphasizes the importance of ensuring that technology meets the needs of diverse populations, especially when it’s intended to improve health. “It’s urgent to explore alternative options to collect reliable data from all users. There is some evidence to suggest that certain light, particularly green light, is more accurate in people across all skin tones,” Daniel Koerber, the study’s co-lead author, said.

I’ve been wondering how kids themselves, especially young ones, define(定义) play. It turns out that there have been quite a few research studies in which young children are asked in various ways to distinguish between play and not play. In a review of 12 such studies, Natasha Goodhall and Cathy Atkinson (2019) concluded that even very young children have a rather clear idea of the difference between play and non-play. Most important for the present discussion, a key characteristic of play for children is that it is chosen and directed by the children themselves.

As one example of such a study, Justine Howard and her colleagues (2006) showed children pictures of other kids involved in various activities and asked them to judge each as “play” or “not play.” It turned out that the most reliable indicator for the children was the presence or absence of an adult. If an adult (generally seen to be a teacher) was present, the activity was most often judged as “not play,” even if the children looked happy and involved. Children were also more likely to judge an activity as play if there was more than one child involved than if a single child was doing something alone.

Howard and her colleagues (2006) also reviewed previous research on children’s understanding of play and concluded that, all in all, children consider an activity to be play if it (a) is controlled by the children, (b) is enjoyable, (c) has no preset goal, and (d) involves pretense. Yay! This list matches reasonably well with the list I generated based on the work of other play researchers and my own observations. I’m apparently not too far off the mark.

Unfortunately, many education specialists who have heard that play is good for children’s learning don’t understand what play is. They develop “play-based learning” programs that go against the first characteristic of play because they are chosen and set up by the teacher and are more-or-less forced upon the children rather than freely chosen by them. Once the first characteristic is destroyed, the others are also generally destroyed.

I think it is hard for teachers to provide much real play for children, because that means giving up control. Moreover, stepping back and letting the children do their own thing may look like laziness or negligence(疏忽) to adult observers.

One of the most deeply-rooted myths in parenting is the so-called Mozart effect, which says that listening to music by the Austrian composer Wolfgang Amadeus Mozart can increase a child’s intelligence. The idea has been promoted by advocates for arts education and by retailers(零售商) who sell special recordings of Mozart’s works for infants(婴儿) and toddlers(学步的儿童). Some pregnant women have even gone so far as to play Mozart recordings on headphones pressed against their bellies.

So, if you have kids or you’re expecting to have them, how seriously should you take the Mozart effect? Will the child who has no access to Mozart s music when born live a life of mediocrity(平庸)? Relax. There is no scientific evidence that listening to Mozart improves children’s cognitive abilities.

The whole idea came from a small study done in 1993, which found that college students who listened to Mozart’s Sonata for Two Pianos in D Major (K 448) showed slight improvement in a test of spatial reasoning( 空间推理). This finding was later turned into something unrealistic by the musician and entrepreneur(企业家) Don Campbell, who in 1997 published the best seller The Mozart Effect: Tapping the Power of Music to Heal the Body, Strengthen the Mind, and Unlock the Creative Spirit. Campbell’s claims about the amazing power of Mozart s music was repeated endlessly in the media and sped up the enthusiasm for Mozart-based enrichment activities.

Since then, scientists have examined the claim that Mozart boosts intelligence and found no evidence for it. The original experiment with college students was reviewed in 1999, and the increase in the students’ spatial skills was found to be negligible. In 2007 the German Federal Ministry of Education and Research commissioned a team of experts to examine the scientific literature regarding Mozart and child development, and they found no reason to believe that it boosted intelligence.