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Body Sense

The Magic Years?

Born to Talk

A Change of Mind

Speaking For Herself
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IT'S A KID'S WORLD: A Change of Mind

How much do children know, and when do they know it? These questions absorb many researchers who study the human mind, especially the development of children's thought and language. In this story, Frontiers joins psychologists as they conduct some unique experiments to find out how the mind of a child works. Two studies -- "Who really stole the muffins?" and "What sticker does the mean monkey take?" -- reveal fascinating clues about children's inability to conceal information.

Curriculum Links
Activity 1: Learning to Deceive
Activity 2: Brain Power: All Fired Up



nervous system, neurons


human brain

data analysis,
tautology, truth tables

learning, trust


Psychologists are fascinated by the human mind and how it works. One aspect, truth and deception, is of special interest because it has long been known that children of a very young age don't seem capable of lying in the same sense as older kids and adults. But why and when this shift in a child's understanding occurs has not always been clear. The deception studies seen on Frontiers provide new insights into how kids learn to deceive. The research provides evidence that children begin to hide information at about four to five years of age. Here are some questions to think about as you watch the show.

  • Why do you think the boy crosses his fingers at the end of the story?

  • Do you think very young children, older kids and adults deceive people for the same reasons?

  • What implications might these studies have for teaching young children about truth and lying?

  • Although lying is unacceptable socially, what validity is there to deception studies, such as those on Frontiers? How important is it to learn about the different stages of cognitive development, and how they affect a person's ability to conceal information?

  • Why do you think the child in the experiment says his mother will think that Katy took the muffins?

  • What are some of the ethical and practical issues involved in setting up deception studies like the ones seen on Frontiers?

  • Do you think deception is learned? Do you think nonhuman primates use deception?

  • Can you find any flaws in the way the experiments you've seen are set up? Could you design an experiment to test similar hypotheses?


Devise a game or mock trial in which you and your classmates try to determine who is lying and who is telling the truth. Do you think there's a way to determine (by facial expressions or speech patterns) who is lying?

  • All of your capacities for memory, learning, dreaming, thinking, perception, problem solving, using language, understanding and processing information rely on activities that take place in your brain, a three-pound lump of gray matter containing about 100 billion neurons.

  • All neurons (or nerve cells) communicate with each other in the same fashion, through an electrochemical process, from neuron to neuron. A chemical release by a cell travels across the gap (synapse) and chemically stimulates the next cell.

  • Nerve impulses travel along pathways formed by connecting neurons. As they travel, they excite an increasing number of nerve cells (a type of impulse magnification called divergence). Sometimes this path branches out, stimulating many other neurons in a chain reaction (amplification). Other times, the neuron stimulates nerves that send the impulse off into two opposite directions (divergence into multiple tracts).

  • Can you make a working model of each type of neural divergence using a set of dominoes?


Scientific American Frontiers
Fall 1990 to Spring 2000
Sponsored by GTE Corporation,
now a part of Verizon Communications Inc.