Binocular Vision: Lecture 18: Development of Normal Binocular Vision

Question 1

1. Critical Period of Development: What is it?
2. Visual experience has its greatest effects at what age?
   a. With markedly diminishing (not completely) effects until about what years of age?

Answer 1

1. Range of ages during which experience has a very powerful effect on the structure and function of the visual system
2. 6 Months of age
   a. 4 to 6 years of age

Question 2

1. Absolute Light thresholds under dark-adapted conditions developed at what month?
   a. Are elevated in what age relative to adults?
   b. The Scotopic Luminosity curve is Adult-like in shape at what age? With a peak near what?

Answer 2

1. at 1st month
   a. in 1-to 3-month old infants relative to adults
   b. at Age of 1 Month; Near 500 nm. (RHODOPSIN DEVELOPMENT)

Question 3

Development of Infant Vision

1. The Photopic Luminosity curve of a 1-month old infant is ADULT-like in what portion?
   a. It has elevated thresholds only in what?
   b. Matures by what?
2. What also develops rapidly?
   a. the Critical Flicker Fusion Frequency (CFF) of a 1-month old infant is about what?
   b. At 2 months of age?
   c. By 3 months?

Answer 3

1. in the Middle and Long Wavelength portion
   a. in the short-wavelength portion of the curve
   b. by 2-3 months
2. Temporal Resolution
   a. about 40 Hz
   b. 50 Hz
   c. at approximately adult level of 60 Hz

Question 4

Development of Infant Vision

1. By 2 MONTHS, infants can start to make what? (Based on what)
   a. But these discriminations are not quite adult-like, as what COLOR SYSTEM IS SLOWER TO DEVELOP?
   b. At what age do INFANTS EXHIBIT TRICHROMATIC BEHAVIOR?

Answer 4

1. some COLOR DISCRIMINATIONS
   a. as the SHORT-WAVELENGTH (BLUE) COLOR SYSTEM
   b. at 6 MONTHS of AGE

Question 5

1. Motion sensitivity develops rapidly as well. If you measure responses to changes in direction of moving dots, infants can DETECT CHANGES in DIRECTION as YOUNG as what?
2. Estimates of visual acuity in young infants can be obtained rapidly with what?
   a. Which present grating of higher and higher spatial frequency in sequence; INFORMATION RECEIVED by the CORTEX AND HAS RECEPTIVE FIELDS to RESOLVE what?

Answer 5

1. 10 to 12 WEEKS of AGE
2. with SWEEP VISUAL-EVOKED POTENTIALS (VEP)
   a. to RESOLVE the TEST TARGET

Question 6

1. Acuity tends to improve as a function of Age in a semi logarithmic fashion.
   a. that is, initially for about EVERY MONTH of AGE, the INFANT’s ACUITY does what?
2. It usually requires what?

Answer 6

1. a. DOUBLES. Responses to stimuli as small as 1-minute arc (20/20) can be demonstrated with VEPs as early as 6 months of age
2. 18-24 months to reach 20/20 using behavioral methods like the preferential looking technique

Question 7

Diagnostic Stripe Width from 1-9 Months

1. 1-2 months
2. 3 months
3. 4 months
4. 6 months
5. 9 months

Answer 7

1. 40’; 20/800
2. 30’; 20/600
3. 20’; 20/400
4. 5’; 20/100
5. 2.5’; 20/50

Question 8

Development of Contrast Sensitivity Function

1. At 2 1/2 MONTHS, Contrast Sensitivity is what?
   a. And Contrast Sensitivity function does not have what?
2. With age, sensitivity increases, and a more dramatic low-frequency roll off emerges; that is, what develops?
   a. The Peak sensitivity shifts toward what?
   * Look at slide 13 of Lecture 18

Answer 8

1. LOW AT ALL SPATIAL FREQUENCIES
   a. have a marked low-frequency roll off as it does in adults; rather, it has a LOW-PASS SHAPE
2. ADULT-LIKE BANDPASS SHAPE develops
   a. Higher Spatial Frequencies, as does the high-spatial-frequency cutoff

Question 9

Cortical Development

1. After about the first 3-4 wks of life in kittens, the eye itself is nearly completely developed, but the visual cortex is still undergoing major changes. With the number and complexity of the interconnections b/w neurons steadily increasing.
   a. As the neurons mature, their center-surround antagonism becomes what?

Answer 9

1. a. STRONGER, and cells become more narrowly tuned to spatial frequency or size.

Secondly, receptive fields gradually become smaller with age, shifting the contrast sensitivity function to higher spatial frequencies

Question 10

The Development of Binocular Vision

1. The basic pattern of retinal correspondence b/w the 2 eyes is determined before birth, so the newborn’s visual system is ready at what?
2. At birth, muscular control of eye movements is not what?

Answer 10

1. at Birth
2. not well developed, which includes binocular coordination
   * Critical period

Question 11

1. A major factor that delays the development of binocular vision is the development of what?
2. Correspondence b/w points in each retina is programmed before birth so that the visual system is already capable at birth of registering the images in the two eyes to achieve sensory fusion. IT IS the OCULOMOTOR CONTROL NEEDED for what?

Answer 11

1. of the accommodative and vergence systems

2. for MOTOR FUSION that is the PROBLEM

Question 12

1. At 8 Wks of age, Infants CONSISTENTLY BLINK in response to what?
   a. If an Infant is Raised with a STRIPED TOY PLACED overhead above the crib, when do they develop this Blinking reflex?
2. Infants have been shown to have an ACCOMMODATIVE RESPONSE as early as what?
   a. How good is a Newborn’s SPATIAL RESOLUTION?
   b. What about their Depth of Focus?
   c. For this reason, Target CLARITY is what?
   d. Accuracy of Accommodative Response Develops by what age?

Answer 12

1. to a Rapidly Approaching Ball
   a. 3 weeks earlier than those who do not.
2. as 2 WEEKS OLD
   a. It’s POOR
   b. It’s quite LARGE
   c. is NOT DETECTABLE
   d. by 3 to 5 months of Age

Question 13

1. During the First 3 Months, the Convergence Responses are what?
2. During the Next 2-3 months of Life, what happens?
3. The ability to detect and make a Consistent and Accurate Vergence response to the introduction of prism DOES NOT OCCUR until what age?
4. Fine Stereoacuity Thresholds actually develop BEFORE infants can make what?

Answer 13

1. They’re BRIEF and are not closely matched to Target Speed
2. Full Convergence first occurs at this time.
3. Until about 6 MONTHS of AGE
4. Before they can make Extremely Accurate Vergence Movements

Question 14

1. Stereopsis is absent in very young infants. However, unlike other visual development, the Improvement in Stereopsis seems Quite sudden at about what age?

Answer 14

1. At About 4 MONTHS OF AGE

Question 15

1. Infants can use AT LEAST MONOCULAR CUES to depth as early as when?

Answer 15

1. As 6-8 WEEKS OF AGE

Question 16

Development of Disparity

1. By what age, can an Infant start tracking a MOVING CONTOUR (STEREOGRAM)?
   a. What is this moving Contour defined as?
2. What about the ability to see FINE STEREOSCOPIC DISPARITIES?
3. Stereoacuity and Visual Acuity depend on the Development of Finely tuned receptive fields, the ability to see stereoscopic disparity develops at a MUCH FASTER PACE than what?

Answer 16

1. 3 1/2 MONTHS!
   a. 45-135-MINUTS of DISPARITY
2. 5-6 months of age (under 1-minute arc)
3. than does Form Perception

Question 17

1. What develops earlier: Ability to see Crossed or Uncrossed Disparity?
2. What 2 things Develop in SYNCHRONY?
3. Stereopsis is probably measurable when the Ocular Dominance Columns are what?

Answer 17

1. CROSSED DISPARITY
2. Fusion and Stereopsis
3. are Fully Segregated

Question 18

1. What anatomic Structures were designed to bring corresponding retinal points together for combination into binocular cells in the STRIATE CORTEX?
2. In monkey, Left eye and Right eye inputs project how?
3. The overlap of info from the 2 eyes w/in layer 4c PREVENTS what?

Answer 18

1. Optic Chiasm, LGN, and Layer 4C of the Striate Cortex. (Binocular cells develop shortly after birth)
2. Equally onto the Same cortical cells in layer 4C for at least 3-4 weeks after birth (PREVENTS BINOCULAR VISION)
3. the existence of Binocularity and Stereopsis, as the cells outside of Layer 4C destined to become Binocular cells, then receive 2 inputs, each with Mixed info from both eyes, rather than 2 inputs with distinct left and right eye info.

Question 19

1. What is the limiting factor on the development of Stereopsis in infants?
   a. Human infants would develop Ocular dominance Columns and Binocular Cells by when?

Answer 19

1. It’s the Development of Clear-cut Ocular Dominance Columns and Functional Binocular Cells
   a. by about 4-6 Months