Your child tells you he didn't eat a cookiedespite the tell-tale crumbs all over his mouth. You call your boss to say you're taking 'a sick day,' feigning a cough while on the phone. You're both lying, but is it the same?

Whether we're 2 years old or 62, our reasons for lying are mostly the same: to get out of trouble, for personal gain and to make ourselves look better in the eyes of others. But a growing body of research is raising questions about how a child's lie is different from an adult's lie, and how the way we deceive changes as we grow.

Developmental psychologists are trying to understand lying through behavior. Neuroscientists are tracking which regions of the brain are activated when we spin lies. Their results could shed light on issues from why a tween lies to your face about breaking a vase to whether young children can be trusted to give eye-witness testimony in court. One intriguing new study suggests that lying may spring from a completely different part of the brain in children compared with adults.

What has become clear from studies including the work of Kang Lee, a professor at the University of Toronto and director of the Institute of Child Study, is that lying is a sign of normal maturation.

Parents and teachers who catch their children lying 'should not be alarmed -- and their children are not going to turn out to be pathological liars,' says Dr. Lee, who has spent the last 15 years studying how lying changes as kids get older, why some people lie more than others as well as which factors can reduce lying. 'The fact that their children tell lies is a sign that they have reached a new developmental milestone.'

Dr. Lee and Victoria Talwar, a colleague he often collaborates with at McGill University, conducted a series of studies in which they bring children into a lab with hidden cameras. Children and young adults age 2 to 17 are enticed to lie by being told not to peek at a toy -- often a plush purple Barney dinosaur -- that is put behind the child's back. The test giver then leaves the room for one minute, ostensibly to answer a phone call, giving the child ample time to peek at the toy. Whether or not the child sneaks a look is caught on tape.

For young kids, the temptation to cheat is 'tremendous' and 90% peek in these experiments. Even adolescents and adults are tempted in similar situations, says Dr. Lee.

When the test giver returns to the room, the child is asked if he or she peeked. At age 2, about a quarter of children will lie and say they didn't. By 3, half of kids will lie, and by 4, that figure is 90%, studies show.

This trend continues until kids are about 15. By that age, nearly everyone who cheated in the experiment will lie about it. The good news: The number of liars begins to decline beyond this age. By 17, the percentage that lies drops to about 70%.

Researchers have also examined why some kids lie more than others, and have found that it isn't related to better moral values or religious upbringing. Rather, it's kids with better cognitive abilities who lie more. That's because to lie you also have to keep the truth in mind, which involves multiple brain processes, such as integrating several sources of information and manipulating that information, according to Shawn Christ, a neuropsychologist at the University of Missouri-Columbia.

The ability to lie -- and lie successfully -- is thought to be related to development of brain regions that allow so-called 'executive functioning,' or higher order thinking and reasoning abilities. Kids who perform better on tests that involveexecutive functioning also lie more.

Shirley S. Wang

• despite [di´spait] prep.尽管 (初中英语单词)
• mostly [´məustli] ad.主要地；多半；通常 (初中英语单词)
• research [ri´sə:tʃ] n.&vi.调查；探究；研究 (初中英语单词)
• deceive [di´si:v] vt.欺骗，欺诈 (初中英语单词)
• director [di´rektə] n.指导者；....长；导演 (初中英语单词)
• institute [´institju:t] n.学院 vt.建立；设置 (初中英语单词)
• normal [´nɔ:məl] a.正规的 n.正常状态 (初中英语单词)
• series [´siəri:z] n.连续；系列；丛书 (初中英语单词)
• hidden [´hid(ə)n] hide 的过去分词 (初中英语单词)
• purple [´pə:pl] n.紫色 a.紫(红)的 (初中英语单词)
• everyone [´evriwʌn] pron.=everybody 每人 (初中英语单词)
• percentage [pə´sentidʒ] n.百分数；比例；部分 (初中英语单词)
• christ [kraist] n.基督 int.天啊! (初中英语单词)
• ability [ə´biliti] n.(办事)能力；才干 (初中英语单词)
• involve [in´vɔlv] vt.卷缠；包括；使专注 (初中英语单词)
• executive [ig´zekjutiv] a.行政的 n.行政官 (初中英语单词)
• behavior [bi´heiviə] n.举止，行为 (高中英语单词)
• testimony [´testiməni] n.证明；证据；表明 (高中英语单词)
• temptation [temp´teiʃən] n.引诱，诱惑(物) (高中英语单词)
• related [ri´leitid] a.叙述的；有联系的 (高中英语单词)
• successfully [sək´sesfəli] ad.成功地 (高中英语单词)
• so-called [´sou ´kɔ:ld] a.所谓的，号称的 (高中英语单词)
• reasoning [´ri:zəniŋ] n.推理，评理 a.推理的 (高中英语单词)
• cookie [´kuki] n.家常小甜饼 (英语四级单词)
• trying [´traiiŋ] a.难堪的；费劲的 (英语四级单词)
• colleague [´kɔli:g] n.同事，同僚 (英语四级单词)
• taking [´teikiŋ] a.迷人的 n.捕获物 (英语六级单词)