The idea that children are like scientists, learning best through firsthand observation and interaction with the world, can be found in Rousseau and Piaget and Montessori and has become a commonplace of progressive education. In Trusting What You're Told Harris attempts, without rejecting that perspective, to swing the balance back towards a proper appreciation of the importance of social learning.

Among other topics, he looks at how children ask questions, find a balance between experience and learning from informants, make moral judgements, and distinguish historical, fictional and supernatural entities. The approach includes a certain amount of the standard fare of psychology, finding clever experiments to provide solid evidence for things that aren't particularly surprising. But Harris also tackles some not so obvious topics — and he ties the results in to broader questions about cognitive development, education, and culture.

Harris begins with early learning, where:

"[children] have a striking capacity to learn from other people's knowledge and experience. A ubiquitous feature of such learning via testimony is the need to think and talk about objects that are 'displaced' — that are not being experienced at the time of the communication. Children display this ability soon after the onset of language acquisition."

(One strangeness here is that Harris uses a primitive "updating file" model for memory, when surely some kind of better-grounded connectionist metaphor would work just as well.)

Studies confirm that children do indeed ask a lot of questions, starting with more factual ones and progressing to requests for explanations, though there is some interesting social and cultural and contextual variation in this. But psychologists and educators have not focused on the cognitive benefits such questions may bring:

"Rousseau, Piaget, and the Isaacses sought to make children better scientists by not answering their questions. Ironically, the evidence in this chapter suggests that it is when children have their questions answered that they respond with the cautious reflection and the persistent curiosity of good scientists."

One major difference between children and chimpanzees is apparent in how they learn from demonstrations:

"Whereas chimpanzees copy selectively, leaving out a demonstrator's evident inefficiencies, children copy more faithfully and include inefficiencies. ... children assume that a demonstration tells you what you are supposed to do and not do in that social setting."

Some experiments with object classification and naive physics show that children find a balance between intuition and guidance:

"children are flexible in their response to adult input. If the perceptual evidence is clear-cut, they typically ignore advice and rely on their own intuitions. ... if the relevant perceptual information is equivocal or hidden, children appear to see adults as offering guidance that is intended to be helpful. Indeed, when an adult concedes the unexpectedness of what the advice proposes, children are all the more willing to accept that adult guidance."

And other experiments explore which people children trust:

"at first, children appraise an informant's trustworthiness mostly in terms of socioemotional factors — their familiarity with, and attachment to, the person. But in the course of the preschool years, they give more weight to the reliability or accuracy of the informant."

Like adults, four year olds tend to prefer informants with "bystander approval", but it is unclear whether children think consensual judgements are likely to be true or whether they think they are reliable guides to cultural norms: "they are especially swayed by people who fit in with the norms and conventions of their own group" and "conform to the judgments of people who have shown themselves to be conformists".

The ability of children to make autonomous moral judgments is explored through studies of independent vegetarians, looking at how they develop such an unconventional idea and how they sustain it, and why they are tolerant of meat-eaters.

"They differ from meat-eating children not in being especially attached to or empathic towards animals, nor in having a radically different conception of how much animals suffer, but in the relative weight that they attach to two conflicting representations of the act of eating meat. Eating meat is typically represented as enjoyable and acceptable. Yet it can also be represented as the cause of unacceptable suffering and slaughter."

Children "are confident about the existence of germs and vitamins; they believe in God; and, for a certain period of childhood, they believe in special beings such as the Tooth Fairy or Santa Claus. Yet they are duly skeptical about the existence of mermaids and ghosts." They also distinguish "endorsed" entities such as God (or, in a highland Mayan community in Mexico, the spirits of the dead) from scientific ones, perhaps "alert to the pattern of testimony that they hear" and aware of "tacit ontological signals that are embedded in what they are told".

When in comes to understanding death and the afterlife, the evidence suggests that, contrary to Piaget's idea of a progression towards rationality, "children first construct a biological conception of death. They eventually elaborate a religious or supernatural conception in addition to that".

Children are quite adept at distinguishing fiction and history, and they also make a distinction between magic and miracles.

"Children who are starting school — and, with prompting, some preschoolers — grasp that the historical past is not a place where regular and fantastic events jostle side by side. They deploy what we might describe as a "magic detector." Using their ideas about what is possible and what is not, they create a frontier between the historical past and the fictional past. They consign the impossible to the world of fiction. This is no mean achievement. Contrary to the claims of Bettelheim, children think of the entire canon of fairy stories as a genre that is distinct from real history."

Stepping back, Harris highlights the importance of social intelligence and of the "ancient tutorial system" through which children learn the regularities of cultural systems:

"children have some appreciation, however tacit, that human life is lived not in some state of nature, but within a cultural group... vital information about what to think and what best to do is gained by listening to other people and paying careful attention to their practices."

He concludes with the suggestion that, rather than as scientists, we should think of children as anthropologists, engaged in participant observation fieldwork.

Harris is open about uncertainties and alternative interpretations, and avoids grandiose claims, but Trusting What You're Told touches on big questions about child development and the origins and evolution of human culture. It's also an easy read, with the technical details omitted, and should be broadly accessible.

Note: References are provided for those who want more detail. The only annoying omission is that the experimental results, while quite simple, are presented without the key detail of sample sizes, making it impossible to judge their statistical power.

December 2015

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