Chapter 5: Seeing, Thinking & Doing in Infancy February 20, 2017

Today Perception Vision Auditory Perception Taste & Smell Touch Motor Development Reaching Self-Locomotion

Development of Perception

Perception & Sensation Basic information processing from external world through sensory receptors in organs and brain Perception Organizing and interpreting sensory information about the objects, events and spatial layout of the surrounding world

Vision Newborns don’t see as clearly as adults Research methods of studying infant vision: Preferential-looking technique Infants shown two patterns/objects, measure how long they spend looking at different things to determine a preference for one over the other Habituation Infant is repeatedly presented with a stimulus until their response declines, then infant is presented with a new stimulus, if infant’s response is elevated we can infer that the baby can discriminate between the old and new stimulus

Visual Acuity Visual Acuity: how sharply one can see By showing infants 1 paddle of grey and 1 paddle with stripes, we can determine infant visual acuity Contrast Sensitivity: infants are really bad at this, they can only detect differences when there is high contrast (i.e. black and white) Early visual experience is important!

Visual Acuity in Young Infants Why do young infants prefer to look at patterns of high visual contrast? They have poor contrast sensitivity. The cones of the eye (light-sensitive neurons highly concentrated in the central region of the eye, the fovea) are highly involved in seeing fine detail and color, they are immature during infancy. They have limited color vision until 2-3 months of age. Children reach full adult acuity around 6 years old

Infant Visual Scanning (a) A 1-month-old looked primarily at the outer contour of the face and head, with a few fixations of the eyes. (b) A 2-month-old fixated primarily on the internal features of the face, especially the eyes and mouth. Infant Visual Scanning The lines superimposed on these face pictures show age differences in where two babies fixated on the images.

Facial Recognition At birth After 12 hours of exposure General bias toward facial configurations After 12 hours of exposure Infant recognizes and prefers his or her own mother's face Over first few months Infants develop a face prototype to help discriminate between faces

Biological Movement Moving dots of light that are easily recognized as a person walking (easy for an adult to recognize) Infants as young as 5 months can see this too! They look longer when it’s a person than when it’s something different http://www.biomotionlab.ca/Demos/BMLwalker.html

Infant Depth Perception Infants use depth and distance cues to navigate their environment Optical expansion Binocular disparity and Stereopsis

Infant Depth Perception Optical Expansion As an object comes toward you it increases in size, this occludes more of the background When I throw a ball at your face, you would duck…babies don’t duck, but they can blink! Infants as young as 1 month blink appropriately! In a way that the object coming toward them wouldn’t hit their eye

Infant Depth Perception Binocular Disparity: Having two eyes means you have two images projected on your retina The closer the object we are looking at, the greater the disparity between the two images Stereopsis: when the visual cortex computes the different images from each eye and produces the perception of depth accurately This process happens around 4 months of age

Auditory Perception Human auditory system is relatively well developed at birth Remember in the womb a fetus can hear the mother’s voice Hearing does not approach adult levels until age 5 or 6. Auditory Localization – A perception of the location in space of a sound source (when a person turns toward a sound they hear) Need a lot of other information to do this accurately – difficult for infants at first, easier for toddlers and young children

Music Perception Singing towards infants is often slower, higher-pitched, suggests more positive affect Infants prefer when you sing to them! 6 month olds were more attentive to videos of their mother singing than speaking Infants can detect small changes in a musical melody (even a 1 note change in the same key!) better than adults Probably due to the lack of culture-specific music formation – we will discuss this more in language development

Taste and Smell Taste: Sensitivity to taste and smell develops before birth. Newborns have a sweet tooth! Smell: Newborns prefer and can differentiate smell of mothers breast milk vs. other milk at 2 weeks old

Infants learn about the environment through active touch Oral exploration dominates for the first few months. Around 4 months of age, infants gain greater control over their hand and arm movements- making exploring their surroundings with touch easier Manual exploration gradually takes precedence over oral exploration Infants learn about the environment through active touch

Reflexes  Milestones  Current views Motor Development Reflexes  Milestones  Current views

Reflexes Reflexes Innate, fixed patterns of action that occur in response to particular stimulation Some stay for the lifetime (sneezing) and others fade over time In newborns Some reflexes have clear adaptive value Others have no known adaptive significance

Reflexes Rooting Reflex: turning head toward direction of touch, and opening mouth Grasping Reflex: will grasp anything that touches their palm Tonic Neck Reflex: turns head, matching arm extended, opposite arm and knee flex Sucking Reflex: begins with oral contact with nipple – Followed by sucking reflex

Motor Milestones Age ranges are based on healthy, North American sample of infants

Culture and Motor Development Early locomotion actively discouraged Modern urban China Aché of rain forest of Paraguay Early locomotion actively encouraged Kipsigis of rural Kenya Groups in West Africa and West Indies

The invention of the diaper… How do cultural practices influence development? Most mature kind of walking!

Reaching Mini-revolution for infants! For the first few months, infants are limited to pre-reaching movements Successful reaching for objects begins at around 3 to 4 months of age

Reaching At about 7 months, as infants gain the ability to sit independently, their reaching becomes quite stable. Reaching shows signs of anticipation, and by 10 months of age, infants' approach to an object is affected by what they intend to do with the object.

Self-Locomotion Around 8 months… Self-locomotion for the first time as they begin to crawl Some kids skip crawling Around 11 to 12 months.. Begin walking independently, using a toddling gait. Some start with “cruising” Wide base, low center of gravity Practice! Practice! Practice! How do you think self-locomotion might be related to child development in other areas?

Visual Cliff Paradigm Gibson and Walk (1960) Originally thought to be support for children having an innate fear of heights Now Karen Adolph and her lab have new ideas! https://www.youtube.com/watch?v=WanGt1G6ScA Gibson and Walk (1960) 6-14 month olds refused to crawl across the deep side even with Mom encouraging them!

Scale Errors Toddlers attempt to do something with a miniature replica object that is far too small for the action to be at all possible Hypothesized to result from failure to integrate visual information represented in different areas of brain https://www.youtube.com/watch?v=OtngSHtz-cc

Concluding Thoughts Finish reading chapter 5 and start studying for test Test next Monday Feb 27th – YOU WILL NEED A GREEN SCANTRON Wednesday- Finish Ch 5 and save time for questions about test