Question

What changes occur in visual and hearing perception during the first two years of life?

Answer 1

What changes occur in visual and hearing perception during the first two years of life?

ANSWER:

Changes occur in visual perception during the first two years of life.

In the early months of life, the visual system is still developing. From birth to complete maturity, the eye increases to three times its size at birth, and most of this growth is complete by age 3; one third of the eye's growth in diameter occurs in the first year of life.

At birth: The pupils are not yet able to dilate fully; the curvature of the lens is nearly spherical; the retina (especially the macula) is not fully developed; the infant is moderately farsighted and has some degree of astigmatism. Functional implications: The newborn has poor fixation ability, because of the mainly subcortical orienting mechanisms, there is limited orienting to single targets from birth to 3 months.

By 3 months: Cortical control of eye/head movements starts to make the integration for attention switching possible; ventral and dorsal stream neural systems start to contribute together to the infant’s visual behaviour; ocular movements are coordinated most of the time; attraction is to both black and white and coloured (yellow and red) targets; the infant is capable of glancing at smaller targets (as small as 2.5 cm, or about 1 in.); visual attention and visual searching begin; the infant begins to associate visual stimuli with an event (e.g., the bottle and feeding).

By 5-6 months: The infant is able to look at (visually examine) an object in his/her own hands; ocular movement, although still uncoordinated at times, is smoother; the infant is visually aware of the environment ("explores" visually), and can shift gaze from near to far easily; the infant can "study" objects visually at near point and can converge the eyes to do so; can fixate at 1 m, or about 3 ft.; eye-hand coordination (reach) is usually achieved by now; the infant may be interested in watching falling objects and usually fixates on the point where the object disappears.

Between 6 and 9 months: Acuity improves rapidly (to near mature levels); the infant "explores" visually (examines objects in hands visually and watches activity in surroundings); can transfer objects from hand to hand and may be interested in geometric patterns.

Between 9 months and 1 year: The child can visually spot a small (2-3 mm) object nearby; watches faces and tries to imitate expressions; searches for hidden objects after observing the "hiding"; is visually alert to new people, objects, surroundings; can differentiate between familiar and unfamiliar people; vision motivates and monitors movement toward a desired object.

By 2 years: Myelinization of the optic nerve is completed; there is vertical (upright) orientation; all optical skills are smooth and well coordinated; acuity is 20/20 to 20/30 (normal); the child can imitate movements, match same objects by single properties (colour, shape), and point to specific pictures in a book.

Changes occur in hearing perception during the first two years of life

An unborn baby's hearing starts to develop early. And at birth, a baby's hearing is fully functioning. Children do respond differently at different stages of growth and development.

A child must babble single syllables (4-6 months) before multiple syllables (7-9 months) before speaking 2-word sentences (18-24 months). Milestone charts represent a “timetable” for mastery of these skills — a guide to “normal” development. Keep in mind, however, that children vary in their development and that an individual child may develop more quickly in one area than in another.

Birth - 3 Months

• Infants are unable to control motor movements; therefore, most actions are reflexes. The most important reflex for speech development is the rhythmic suck swallow pattern, established three months prior to birth. • Produces sounds such as fussing, crying, burping and cooing. • Produces most sounds on exhalation with lengthy vowel-like sounds (back vowels) • Makes single vowel sounds “ah” “eh” “uh” - one syllable • Sustains cooing 15-20 seconds • Different kinds of crying for pain and hunger

4 - 6 Months

Vocalizes in self-initiated sound play • Coos to music • Vocalizes “ma” or “mu” • Tries to repeat heard sound sequences • Babbling begins • Experiments and plays with sounds (yells, gurgles, blows raspberries and bubbles) • Varies volume, pitch and rate (suprasegmentals)

7 - 9 Months

Produces sounds in one breath • Enjoys imitating sound sequences • Babbles with some CV syllables (“bababa”) • Uses /m/, /n/, /b/, /p/, /t/, /d/ in babbling • Imitates sounds, cough, tongue clicking (increased tongue tip activity), etc. • Imitates some onomatopoeias • Babbling shows pitch and inflectional changes • Copies (sometimes inaccurately) intonational contours • Beginning of adult speech (starting to develop certain vowels, syllables, diphthongs)

10 - 12 Months

Uses variegated (nonreduplicative) babbling (“dageedagee”) • Begins changing babbling to real words • Continues imitating sounds • Begins using more back vowels, central vowels and consonant

12 - 18 Months

Uses echolalia and unintelligible speech/jargon • Omits some initial consonants and almost all final consonants • Continues to develop vowels and diphthongs • Varies pitch when vocalizing • Uses 21 different phonemes • Imitates words inexactly

18 - 24 Months

Jargon peaks at 18 months • Correctly pronounces most vowels • Uses /m/, /p/, /b/, /w/, /n/, /t/,/d/ correctly in the beginning of syllables and short words • Two years: 25%-50% intelligibility • Commonly uses 25 different phonemes • Uses beginning consonants • Word-final consonants emerge • Pitch is lower and more stable