During this stage, the child learns to take initiative, and prepares for leadership and goal achievement roles. Activities sought out by a child in this stage may include risk-taking behaviors, such as crossing a street alone or riding a bike without a helmet; both these examples involve self-limits. Within instances requiring initiative, the child may also develop negative behaviors. These negative behaviors are a result of the child developing a sense of frustration for not being able to achieve a goal as planned and may engage in negative behaviors that seem aggressive, ruthless, and overly assertive to parents. Aggressive behaviors, such as throwing objects, hitting, or yelling, are examples of observable behaviors during this stage. Preschoolers are increasingly able to accomplish tasks on their own and can explore new areas. With this growing independence comes many choices about activities to be pursued. Sometimes children take on projects they can readily accomplish, but at other times they undertake projects that are beyond their capabilities or that interfere with other people's plans and activities. If parents and preschool teachers encourage and support children's efforts, while also helping them make realistic and appropriate choices, children develop initiative—independence in planning and undertaking activities. But if, instead, adults discourage the pursuit of independent activities or dismiss them as silly and bothersome, children develop guilt about their needs and desires. The aim to bring a productive situation to completion gradually supersedes the whims and wishes of play. The fundamentals of technology are developed. The failure to master trust, autonomy, and industrious skills may cause the child to doubt his or her future, leading to shame, guilt, and the experience of defeat and inferiority. The child must deal with demands to learn new skills or risk a sense of inferiority, failure, and incompetence. "Children at this age are becoming more aware of themselves as individuals." They work hard at "being responsible, being good and doing it right." They are now more reasonable to share and cooperate. Allen and Marotz (2003) also list some perceptual cognitive developmental traits specific for this age group. Children grasp the concepts of space and time in more logical, practical ways. They gain a better understanding of cause and effect, and of calendar time. At this stage, children are eager to learn and accomplish more complex skills: reading, writing, telling time. They also get to form moral values, recognize cultural and individual differences and are able to manage most of their personal needs and grooming with minimal assistance. At this stage, children might express their independence by talking back and being disobedient and rebellious.