<P> Where maturity is an earned status that often carries responsibilities, immaturity is then defined in contrast by the absence of serious responsibility and in its place is the freedom for unmitigated growth . This period of growth is particularly important for humans, who undergo a unique four - stage pattern of development (infancy, childhood, juvenility, adolescence) that has been theorized to confer a number of evolutionarily competitive benefits (Locke & Bogin, 2006). In infancy, motor development stretches long into the early years of life, necessitating that young infants rely on their mothers almost entirely . This state of helplessness provides for an intensely close bond between infant and mother, where separation is infrequent and babies are rarely out of a caregiver's arms . For non-human primates and all non-human mammalian species the growth of the first permanent molar marks the end of lactation and the beginning of foraging, setting an early requirement for independence . Human children, on the other hand, do not have an advanced motor control capable of foraging and also lack the digestive capacity for unprepared food, and so have always relied on the active involvement of their mother and other caregivers in their care into childhood . </P> <P> The pre-frontal cortex, which is responsible for higher cognitive functions such as planning, decision - making, judgment and reasoning, develops and matures most rapidly during early adolescence and into the early 20s . Accompanying the growth of the pre-frontal cortex is continued synaptic pruning (the trimming of rarely used synapses) as well as increased myelination of nerve fibers in the brain, which serves to insulate and speed up signal transmission between neurons . The incomplete development of this process contributes to the finding that adolescents use their brain less broadly than do adults when asked to inhibit a response and show less cross-talk (communication across diverse regions of the brain). The brain's "cross-talk" may be related to decision - making concerning risk - taking, with one study of American adolescents finding delayed reaction time and decreased spread across brain regions in a task asking them to determine whether a dangerous action is a good idea or not . Steinberg observes that there is close overlap in the activated brain regions for socioemotional and reward information, which may pose a challenge when making decisions in the most high - risk peer contexts . One study found that preference for small immediate rewards over larger long - term rewards was associated with increased activation with regions primarily responsible for socioemotional decision - making . </P> <P> The definition and determination of maturity has been applied to the issue of criminal responsibility of juvenile offenders and to a number of legal ages . The age of majority, the most broadly applied legal threshold of adulthood, is typically characterized by recognition of control over oneself and one's actions and decisions . The most common age threshold is 18 years of age, with thresholds ranging from 14 to 21 across nations and between provinces . Although age of majority is referred to as a jurisdiction's legal age, the legal ages of various other issues of legal maturity like sexual consent or drinking and smoking ages are often different from the age of majority . Aside from age - based thresholds of maturity, restrictions based in a perceived intellectual immaturity also extend to those with a variety of mental impairments (generally defined as anyone with a mental disability that requires guardianship), with laws in place in most regions limiting the voting rights of the mentally disabled and often requiring the judgment of a court to declare fitness . Similar to those restrictions placed on children, persons with mental disabilities also have freedoms restricted and have their rights assigned to parental guardians . </P> <P> One reason cited for why children and the mentally disabled are not permitted to vote in elections is that they are too intellectually immature to understand voting issues . This view is echoed in concerns about the adult voting population, with observers citing concern for a decrease in' civic virtue' and' social capital,' reflecting a generalized panic over the political intelligence of the voting population . Although critics have cited' youth culture' as contributing to the malaise of modern mass media's shallow treatment of political issues, interviews with youth themselves about their political views have revealed a widespread sense of frustration in their political powerlessness as well as a strongly cynical view of the actions of politicians . Several researchers have attempted to explain this sense of cynicism as a way of rationalizing the sense of alienation and legal exclusion of youth in political decision - making . </P>

Who will typically have the most decision-making ability in this relationship