Full context:   Psychologists assert that time seems to go faster with age, but the literature on this age-related perception of time remains controversial. Those who support this notion argue that young people, having more excitatory neurotransmitters, are able to cope with faster external events. Some also argued that the perception of time is also influenced by memory and how much one have experienced; for example, as one get older, they will have spent less part of their total life waiting a month. Meanwhile, children's expanding cognitive abilities allow them to understand time in a different way. Two- and three-year-olds' understanding of time is mainly limited to "now and not now". Five- and six-year-olds can grasp the ideas of past, present, and future. Seven- to ten-year-olds can use clocks and calendars. Socioemotional selectivity theory proposed that when people perceive their time as open-ended and nebulous, they focus more on future-oriented goals.