sensitive period {Ans: A limited phase in an animal's development that is the only time when certain behaviors can be learned.}Neuron {Ans: a nerve cell; the basic building block of the nervous system}Emotional development of infancy {Ans: Develops self concept, has tantrums if frustrated, little control over their emotions}motor development {Ans: the progression of muscular coordination required for physical activities}vestibular system {Ans: three semicircular canals that provide the sense of balance, located in the inner ear and connected to the brain by a nerve}Social Development {Ans: The increasing complexity of behaviour patterns used in relationships with other people.}