SOCIAL EXHAUSTION
In “The Social Cure,” Jolanda Jetten, Catherine Haslam, S. Alexander Haslam and Nyla R. Branscombe state: “Membership in lots of groups—at home, work, the gym—makes us healthier and more resilient.” But we are not all the same. For extroverts that formula makes sense, but for introverts it does not. Unlike extroverts, who are energized by social mingling, introverts typically find the experience at the least uncomfortable and, more often than not, downright exhausting.

“Chrystal Ocean”
adapted from a comment at www.ScientificAmerican.com/Mind-and-Brain

COGNITION IN THE WOMB
As a published freelance researcher specializing in prematurity, I must point out that Christof Koch in “When Does Consciousness Arise?” [Consciousness Redux] really short-changes the fetus. Learning, memory and language begin in utero. Psychologically, the fetus starts learning with the occurrence of the first reflexes. Reflexes are the road to exploration and discovery—predominantly about the self—and to learning new behaviors. The first type of learning to emerge is habituation, when the fetus shows a decreasing response to a stimulus each time it appears. A few babies show habituation as early as 23 weeks of gestation, and by 29 weeks all healthy fetuses can do it. Habituation shows that memory and cognition are developing.

In one recent example, a Dutch team led by Jan Nijhuis established that fetuses as young as 30 weeks’ gestational age responded with a startle to a specific stimulus, in this case, a “vibroacoustic stimulation.” After repeated stimuli, the fetuses stopped responding, meaning the stimulus had become a “safe” one—that is, the fetuses habituated. That study is one of many that offer evidence for fetal learning and memory.

Paula M. S. Ingalls
Bernard, Maine

PAIN AND HORMONES
As a physical therapist, I found “I Do Not Feel Your Pain,” by Ingrid Wickelgren, extremely interesting, but I question the part of the article that discusses female hormone levels and the effect they have on pain perception. I find that women (myself included) have more pain toward the end of their menstrual cycle when estrogen is lower, not when estrogen is higher as the article suggests. I have also experienced more pain while taking birth-control pills. Perhaps there is another chemical phenomenon at work.

“pt_char”
adapted from a comment at www.ScientificAmerican.com/Mind-and-Brain

KNOW MUCH ANTHROPOLOGY?
Wray Herbert’s article “Don’t Know Much Biology” [We’re Only Human] exaggerates the human problem with learning biology because he relies on studies of modern urban Americans who have essentially no interaction with nature. All of us anthropologists who study traditional rural cultures are struck by the incredible knowledge of biology that even very young children have. They not only recognize hundreds of species of plants and animals, but they also know which varieties are related to which others, what is alive and what is not, and so on—the very things that the American students in the studies Herbert cites do not know. Recent studies of this effect in traditional cultures by anthropologist Norbert Ross of Vanderbilt University and psychologist Douglas Medin of Northwestern University confirm it rigorously.

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This point would not be worth making if it did not relate to another article in the same issue, “A New Vision for Teaching Science,” by J. Randy Mc­Ginnis and Deborah Roberts-Harris. They tell of “new” discoveries in science teaching—but what they recommend is exactly what traditional people do! They teach their kids through actual practice, starting with a limited range of activities and expanding outward. Kids are apprentices and doers, not mere memorizers of stray facts for multiple-choice tests. As a result, they actually learn. They have to; a Maya child (most of us who look at this seem to study the Maya) who was as ignorant of his or her environment as an urban kid in the U.S. would not last long.

E. N. Anderson
Professor Emeritus of Anthropology
University of California, Riverside

HAPPY YOUNG, HAPPY OLD
Say Cheese,” by Jordan Lite [Head Lines], discusses a study in which the brightness of kids’ smiles in their childhood photographs was found to predict their future marriage success. A cheerful, spontaneous smile is a good prognosticator of a cheerful personality—this is a proverbial no-brainer. And most people find it is a real pain to be around unhappy people or even someone who seems unhappy.

How much money was paid for this “study” to determine the obvious?

“Lowndes”
adapted from a comment at www.ScientificAmerican.com/Mind-and-Brain

MORE ON NIGHT OWLS
In “Early Risers Crash Faster [Head Lines], Siri Carpenter explains a study in which so-called night owls got a boost in energy 10 hours after waking up that the early risers did not experience. But the article did not discuss each group’s duration of sleep. Was there a difference in the number of hours slept between the early risers and the night owls? In addition, did the researchers measure in the lab or otherwise take in­­to account each group’s quality of sleep?

“jh443”
adapted from a comment at www.ScientificAmerican.com/Mind-and-Brain

CARPENTER RESPONDS: The researchers chose subjects who all had equivalently healthy sleep, and the study was designed to let the sleepers follow their natural, preferred sleep schedule. On the nights before the cognitive tests, each subject’s bedtime and wake time—and therefore total duration of sleep—were individually tailored to their previously stated sleep preferences (which were verified by biometric surveillance for several nights prior to their night in the sleep lab). Most subjects appear to have slept around eight hours. The complexity of this study design, in my opinion, contributes to the study’s rigor.

ERRATA “Calendar” [July/ August 2009] incorrectly stated that Herbert Jasper made the first electrical tracing of the human brain in 1934. The first electroencephalogram (EEG) recording was in fact made by German physician Hans Berger of the University of Jena in 1924. Berger published his findings in 1929 and coined the terminology for EEG as well as for alpha and beta waves.

“A Patchwork Mind,” by Melinda Wenner [July/August 2009], incorrectly stated that almost all children with Prader-Willi syndrome suffer from psychotic disorders. Although psychosis affects most people whose Prader-Willi syndrome arises from having an extra chromosome from one parent, these people constitute a minority of cases. A 2008 survey by the Prader-Willi Society of America polled 279 parents of children with the syndrome and
found that about 7 percent of the children had been diagnosed with psychosis.