Developmental psych ch 5: Perception and motor development

vision

40 to 50% of mature cerebral cortex is involved with visual processing. infants begin visual exploration minutes after leaving the womb. Vision improves extremely rapidly within the first months. Its not until 2 or 3 months that infants can track moving objects smoothly. infants have 20/120 vision in their first month and by 2 or 3 months, infants color vision is similar to that of an adult and 20/20 vision. 4 or 5 month year olds like to look at what is considered the most pleasant colors, red and blue. infants perceive the differences in the objects and pictures at 9 months but they dont understand 2 dimensionality yet so they try to pick it. it isn't until 19 months, after substantial experience with pictures that the infants recognize this. Methods for studying visual attention in infant------------- preferential-looking technique: a method for studying visual attention in infants that involves showing infants two patterns or two objects at a time to see if the infants have a preference for one over the other. habituation techniques

motor developement

Depends on multiple factors not only maturation. The type culture affects how much movement an infant is able to execute. Less movement at a young age would inhibit or slow motor development. Motor skills also involve the development of multiple independent components. This includes muscle development, postural control, development of various perceptual and motor skills, and more. Motor development does not occur in isolation. Motor development drives perceptual, cognitive, and even social development. Motor Milestones: - lifts head (4 weeks) - arms for support (2-4 months) - reaching/grasping (3-4 months) - sits without support (5-7 months) - Crawls (5-11 months, average 7 months) - walks alone (11-14 months)

Infants face perception

During the first month, infants mostly focus on the out edges of the face and part that have sharp color contrast. 2-3 months able to explore the inner features of face more thoroughly. from spending a lot of time together, infants come to recognize and prefer their mother's face than the face of another woman. Infants prefer faces that are right side up. Infants can distinguish between different individuals in a different species if they were exposed to them at young age and have developed a prototype of what they look like. Usually, around 6 months they are still developing so differences in individuals can still be distinguished. By the time they reach 9 months, whoever they were raised with is the set prototype of a face they have in their head. If they were not exposed to other races besides their own at a young age, they will have difficulty distinguishing the differences in individuals' faces in that race. Other race effect: The cross-race effect (sometimes called cross-race bias, other-race bias or own-race bias) refers to the tendency to more easily recognize members of one's own race

reaching

Reaching takes a while to develop because it requires the development of multiple independent components. This includes muscle development, postural control, development of various perceptual and motor skills, and more prereaching movement: clumsy swiping movements by young infants toward the general vicinity of objects they see. at around 3 to 4 months infants begin to successfully reach for things. Increased interaction with objects gives infants additional opportunity to learn about the social world, namely, how people interact with objects. This makes infants better interact with social partners and causes an increase in interest for social partners. at 7 months babies learn to sit so their ability to reach for things becomes more stable and smooth. This allows infants to be able to reach for things that are far away from them. Greater interaction with objects also improves the ability of the child to perceive 3D images. at about 10 months, infants learn to shape hand before grabbing based on how object looks

dynamic systems theory

a class of theories that focus on how change occurs over time in complex systems. dynamic systems theories depict that development is a process in which change is the only constant. This means that things are never stable, there are no periods of brief transition periods of change, there is only constant change. (Dynamic) Proposes that all points in development, thought and action change from moment to moment in response to the current situation, the child's immediate past history, and the child's long term actions in related situations. (Systems) depicts each child as a well-integrated system in which many subsystems (perception, action, attention, memory, language, social interaction, and so on) work together to determine behavior. dynamic systems theory emphasizes innate motivation (Such as their interest in the social world), precise analysis of problem-solving activity, formative influence by other people (such as culture) are key catalysts that drive development to occur. How change occurs in dynamic systems theory: occurs through mechanisms of variation and selection, much like biological evolution. Babies use multiple ways of achieving the same goal. Over time, the more effective and efficient method is utilized more frequently. Chapter 5 part 2, page 3, first slide. For a framework for dynamic systems theory.

optical expansion

a depth cue in which an object occludes increasingly more of the background, indicating that the object is approaching. The visual image of the object is getting bigger the more it gets near you, covering more of the background. Infants cant duck when a object is approaching so they blink instead. Babies after a month of age blink defensively when objects approach, but preterm infants show a delayed reaction. This indicates optical expansion is a matter of maturity and not solely visual experience.

Music perception

infant directed singing is preferred by infants over infant directed speech. It is slow and high pitched, indicating affection. Studies show that infants prefer consonant music over dissonant and that this taste isn't a matter of experience, but is innate. Infants can detect changes in rhythm and pattern of music better than adults because they lack perceptual narrowing early in development.

touch

infants initially explore what objects are like by oral means but later in development (about 4 months), where they gain greater control over their movements in limbs, manual exploration supersedes oral exploration.

taste and smell

infants prefer the smell of their mothers and natural food sources like their breast milk.

reflexes

innate, fixed patterns of action that occur in response to particular stimulation. grasping reflex: infant closes fingers on anything that presses against their palm (disappears after 3-4 months) rooting reflex: infant turns head to the direction to where they have been touched and open mouth (disappears after 3 weeks). Oral contact with nipple sets off sucking reflex which is immediately followed by a swallowing reflex. Moro/startle reflex: the response to a sudden loss of support, like the infant feels like its falling. (disappears before 6 months) These reflexes listen are not fully automatic, for example rooting reflex is only present in hungry babies. Most neonatal reflexes disappear on schedule. If they don't disappear, its usually a sign of neurological problem. Strong reflexes at birth indicate a babies central nervous system is in good shape. Stepping reflex: a neonatal reflex in which an infant lifts first one leg and then the other in a coordinated pattern like walking. Was once thought it disappears just like other neonatal but it actually remains, its just that the changing ratio of leg weight to strength masks it. (disappears 2 months, reappears after 12 months)

Visual milestones

optical expansion 3-4 weeks binocular disparity and stereopsis 3-4 months monocular cues 3-7 months - perspective and texture 5-7 months - occlusion 3-4 months object segregation 2 months

contrast sensitivity

the ability to detect differences in light and dark areas in a visual pattern. infants have poor contrast sensitivity so they prefer patterns of high visual contrast. One reason for this is that infants have underdeveloped cones. Cones: the light-sensitive neruons that are highly concentrated in the fovea (the central region of the retina)

self locomotion

the ability to move oneself around the environment. Occurs at about 8 months of age. infants initially begin by crawling and start walking around 11-12 months. Walk with a very wide stance, and feet are on the ground 60% of the time when walking. Studies show that wearing a diaper negatively affects the way an infant walks. Wearing a diaper will cause an immediate less mature pattern of walking. infants adjust their mode of locomotion based on their perception of the properties of the surface they are going to traverse. like if the surface is smooth or rigid. Depth perception of cliffs depends on how much experience a baby has with crawling and NOT with how old they are. Once the baby learns to walk, they have to relearn this depth perception because of the change in posture. Scale errors: the attempt from a child to perform an action on the object that is impossible due to how small the object is relative to the child. Are the result of failure to integrate visual information from two different areas of brain. Scale error diminishes with development. Ex: trying sit on a mini chair or get in a mini car.

intermodal perception

the combining of information from 2 or more sensory systems. between 5 and 7 months, infants notice the relation between human faces and voices. infants prefer sounds and sights that correlate with each other. ex: seeing stepping and sound synchronizes with the step.

Perceptual narrowing

the concept that the inexperienced infants can detect differences in stimuli from music rhythm, facial features, and other things involving the senses better than adults because they lack the experience. As infants develop more experiences, developmental changes fine tune the perceptual system. this important because it allows infants to become especially attuned to the patterns of biological and social stimuli that are important to their environment. However, this also causes the person to only be able to distinctly detect a few things which explains why adults become less capable of making a distinction between stimuli than they were earlier in development.

Binocular disparity

the difference between the retinal image of an object in each eye that results in two slightly different signals being sent to the brain. Emerges early in infants due to the simple fact of having two eyes. Greater binocular disparity when object is closer. stereopsis: the process by which the visual cortex combines the differing neural signals caused by binocular disparity, resulting in the perception of depth. emerges around 4 months.

object segregation

the identification of separate objects in a visual array. basically understanding the boundaries between different objects. babies use motion as a cue to identify boundaries to indicate two objects as separate entities. If cup was picked up from a saucer shows two different objects for example. Infants don't innately have the ability to identify that a singular object in motion is a cue that the object is one object (common motion). This skill has to be learned. Usually, around 2 months infants show evidence of this. Infants also use physical separation around 2 months to tell between separate objects. if an infant looks longer, it shows that they recognize two different objects

auditory localization

the perception of location in space of a sound source. Infants indicate they recognize where the sound is coming from by turning to it. Infants have small heads so the timing for each sound that reaches each ear and the loudness of the sound is much faster so it's much harder to process. Also infants dont have a well developed auditory spcial map (mental repesentation of how sounds are organized in space) because they havnt developed the experience of integrating information from what they see and touch.

perceptual constancy

the perception of objects as being constant size, shape, color, etc., in spite of physical differences in the retinal image of the object. objects moving far away but you know that its not getting smaller babies have perceptual constancy, so visual experience is not necessary for size constancy.

monocular depth (pictoral) cues

the perceptual cues of depth (such as relative size, textures, and interposition) that can be perceived by one eye alone. used to portray depth in pictures and develop around 6 to 7 months.

perception

the process of organizing and interpreting the sensory information

sensation

the processing of basic information through the sense organs and the brain from the outside world.

visual acuity

the sharpness of visual discrimination.