路易斯和布鲁克斯认为，当儿童不借助于观察偶然行为，也能通过视觉认出自己时，他们就达到了发育的一个重要里程碑。
Lewis and Brooks argued that an important developmental milestone is reached when children become able to recognize themselves visually without the support of seeing contingent movement.
同时，建议家长采纳和促进健康的生活方式，因为儿童的行为常常是通过观察和适应形成的。
Simultaneously parents are advised to live and promote a healthy lifestyle because children's behavior is often shaped by observation and adaptation.
学校老师也被招募进来作为家庭以外儿童行为的观察员。
School teachers were also recruited as observers of child behaviours outside homes.
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