PSYC 4220 1st Edition Lecture 9 Outline of Last Lecture I II Cesarean Sections Birth Complications A Low birth weight B Post mature III After Birth Outline of Current Lecture I II Infant Reflexes Motor Development and Physical Growth A Dynamic Systems Theory Current Lecture Infant Reflexes Unlearned involuntary response to stimuli See table 5 3 page 123 Present at birth or shortly after Most fade during first year as brain matures Two categories Survival reflexes Offer protection or satisfy basic survival Examples Breathing eye blink Swallowing sucking and rooting Swimming Infant reflexes No clear survival value Examples Babinski reflex tickle babies foot and they fan out toes and then scrunch them up Grasping reflex starts fading at about 3 months Stepping reflex starts to fade at 8 weeks but this will strengthen that part of the brain when we actually start walking their heads are still too heavy and their legs are too weak Moro reflex when it feels like it s head and neck aren t being supported they thro their arms wide and bring them back in Infant states sleeping Born with organized patterns of activity or states different degrees of awareness to internal and external stimuli 70 of time spent sleeping alert only 2 3 hours per day By 3 7 months most people sleep for at least 6 hour stretches at night nap 2 3 times per day 2 weeks before birth to 2 months after 50 of sleep is REM sleep by 6 months only 25 30 is REM sleep Motor Development and Physical Growth Four principles of growth Cephalocaudal development proceeds from the head downward More able to use legs than arms exception to cephalocaudal theory Proximodistal proceeds from middle of the body outward Hierarchical integration simple skills develop first then are combined into complex skills Independence of Systems Different body systems develop at different rates Motor Development Compare children to developmental norms typical age range of mastery of a skill Dynamic Systems Theory Development of motor skills involves coordination of a vast number of skills body areas environmental influences Emphasizes the importance of babies motivation in development of motor skills Environment can influence speed of development within limits Babies in the U S typically walk around 1 whereas babies that aren t allowed to roll around and play as much walk a lot later and then in Africa where they practice motor skills digging holes to help them learn to sit up practice stepping reflex but these practicing techniques are within reason genetic physical development is also a factor Major milestones figure 5 7 page 125 Locomotion Roll over 2 4 months Sit without support 6 months Crawling 8 10 months Many babies begin moving before this but it isn t a real crawl more of a slither Many babies learn to move backwards first Walking 11 13 months Manipulating objects Grasping reflex gone 2 4 months good because start to develop voluntary control Voluntary reaching 3 months Ulnar grasp grasp things between fingers and palm 4 6 months Pincer grasp grasp things between thumb and forefinger 8 9 months Scribble with crayon 16 months Copy simple line build with blocks 2 years Physical Development Also follows principles of growth especially cephalocaudal and proximodistal Height and weight increase rapidly over first 2 years Half of adult height by age 2 triple or quadruple birth weight Grow super fast at a huge rate in spurts over the first two years Not proportional growth though If we continued growing at that rate until the age of a18 we would be 12 feet tall and way several tons