visual acuity testing paired preference procedure forced choice preference procedure optokinetic...
TRANSCRIPT
Visual Acuity Testing
Paired Preference Procedure Forced Choice Preference Procedure Optokinetic Nystagmus Visual Evoked Potential– a form of ERP
Visual Acuity
At birth, acuity is approximately 20/400 to 20/800
By 4 to 5 months infants are no longer “legally blind” (e.g., 20/200)
Reaches 20/20 between 8 to months VEP suggests faster development– why?
Color Vision
When can babies discriminate color? Separating Hue, Brightness & Saturation
Categorical Perception of Color R O Y G B I V
Can Infants discriminate color?
Problem in determining color discrimination Color and Brightness are two independent aspects of
any image Confounding color differences with brightness
differences – are infants (or adults) discriminating differences on brightness or color? Brightness is a perceptual characteristic not simply a
physical characteristic– must be determined by testing vision
Solution – in adults. 1) Have adults match different colors for brightness 2) Compare different colors previously matched for
brightness
Matching Brightness – adjust the brightness (not hue) of the inner circle to match that of the outer one
Can Infants discriminate color? – cont. Problems with adult solution to
brightness/color confound for infant testing Can’t ask infants to ignore color and compare only
brightness Can’t use adult matching data to apply to infants.
Brightness likely differ considerably for babies – because of pigmentation in infants’ eyes.
Brightness matches even from one adult to another and likely same for babies – must test each individual separately
Solution – use a clever habituation task to get babies to IGNORE brightness
Auditory Thresholds
Tested with High Amplitude Sucking Procedure
Newborns hear above 27 decibels
Can discriminate about 1 note on the musical scale
Newborn Speech Perception
H.A.S. procedure is also used to study speech perception
P. Eimas: Can newborn discriminate “B” from “P” sounds
Can infants discriminate “R from “L” Or Pittsburgher’s
Harry from Hairy
Early Speech Perception
Is this a innate specialized ability? Abstraction of ongoing speech Invariance over individuals, gender, dialect Dialect Study (At 11 mo but not 4)
Pittsburgh babies can’t discriminate Chinese from Taiwanese
Can discriminate Pgh from New York Can discriminate 2 novel dialects (Southern from
New York)
Newborn Taste Abilities
Can newborns discriminate the four basic flavors of : Sweet, Sour, Bitter, Salty
Newborns prefer sweet and salty—why?
Sweet flavors can sooth the newborn
Newborn Smell
Newborns react positively and negatively to different smells
Can infants detect the smell of their mothers?