P3D Re: VM and kids

[abram klooswyk <abram.klooswyk@xxxxxx>]

MOST interesting postings from parents reporting on stereovision of
there kids. The question to be asked is: did you LIKE it that they could
see it ? If so, keep it for yourself, especially don't post it to P3D,
nobody else will believe you...
Of course in a real test of the ability to see 3D in VM, the kids should
offered 3D VM's AND 2D VM's (flatties, two identical pictures in a VM
reel) at random. Of course, the person giving the reels should not know
whether it was 3D or 2D. In advance the possible responses should be
settled and rated. Only after the tests the 2D or 3D answers should be
decoded. Grandparents of course should be not be allowed within 10 miles
from the place where the test is executed, they would spoil the test at
closer range....

More serious, I'm afraid not many Ph D's still are to be gained on this
subject (Bob Wier's suggestion P3D Digest 2867) because so many research
has been done. I have not recently looked for literature on this
subject, in my older files are some 15 papers from 1980-1990. 

A few exemples: 
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Fox, Robert; Aslin, Richard N; Shea, Sandra L; Dumais, Susan T; 
"Stereopsis in human infants" Science 1980 Jan;207(4428):323-324.
Stereoscopic depth perception was tested in human infants by a new
method based on attracting the infant's attention through movement of a
stereoscopic contour formed from a dynamic random-element stereogram.
The results reveal that stereopsis emerges at 3 1/2 to 6 months of age,
an outcome consistent with evidence for rapid postnatal development of
the visual system.

Petrig, Benno; et al; "Development of stereopsis and cortical
binocularity in human infants "  Science 1981 Sep;213(4514):1402-1405.
Dynamic random-dot stereograms and correlograms were used to elicit
visually evoked brain potentials from 17   7-48 wk old human infants.
These potentials were compared with potentials evoked by classical
checkerboard pattern reversal. Results indicate that Ss began to produce
stereoscopically evoked potentials at the age of 10-19 wks, several
weeks after showing classical checkerboard-evoked potentials. Findings
suggest that the onset of cortical binocularity preceded stereopsis.

Broadbent H; Westall C; "An evaluation of techniques for measuring
stereopsis in infants and young children." Ophthamic physiological
Optics 1990 Jan;10(1) 3-7
Demonstrating stereopsis is valuable in vision screening of infants and
toddlers, since its presence rules out the possibility of profound
visual deficits. We assessed the performance of 55 infants and young
children on clinically available tests, the Lang, the Frisby and the
TNO. The results were compared with those found using a computerized
dynamic random dot stereogram.
Most of the children tested were under 3 years of age and 10 were aged
under 1 year. The Lang test was passed by 74%, including 50% of those
under 1 year. The Frisby test was passed by 65%, but by only 20% of
infants under 1 year.  Forty-nine per cent passed the TNO test; none
were under 1 year. The computerized stereogram was passed by 42.5% of
those tested, including 100% of those over 3 years old.
Both this test and the TNO presented difficulty in testing infants
between 8 months and 2 years because of the increased likelihood that
these children would reject the red/green glasses. We recommend  that
the most appropriate stereotest is largely based on whether the child
will tolerate red/green glasses. We would use the dynamic random dot
test for infants under 8 months of age, the Lang or Frisby stereotest
for infants from 8 months to 30 months, and the TNO or dynamic random
dot stereogram after this age.  

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These are some old abstracts, new can be found on the Web in Medline
http://www.ncbi.nlm.nih.gov/PubMed/
This a free service, no Passwords, no medical qualification required.
After writing the above, a few moments ago I have submitted the
keywords:
infant*  stereopsis
and from the 8 million articles in the database of the (USA) Nat Library
of Medicine I got 288 references, from 1998 back to 1975.
One of the recent ones reads:
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J Pediatr Ophthalmol Strabismus 1998 Mar;35(2):86-90 
Infant random dot stereoacuity cards.
Birch EE, Salomao S
Retina Foundation of the Southwest, Dallas, TX 75231, USA. 
PURPOSE: The overall goal was to develop a simple test of random dot
stereoacuity that can be used during the first 24 months of life to
measure sensory outcomes following treatment of ophthalmopediatric
disorders, both in the context of clinical trials and in the context of
clinical management. 
METHODS: A series of random dot stereoacuity test cards were constructed
using vectographic vertical bar stimuli with crossed disparities ranging
from 1735 to 45 sec. A
two-alternative, forced-choice, preferential-looking test protocol was
used to measure stereoacuity in 95 healthy term infants (173 tests) over
the 1.5-to-24-month age range. Success rate, validity, and tolerance
limits for normal performance as a function of age were evaluated.
RESULTS: The success rate was high (158 of 173 tests; 91.3%).
The maturation of random dot stereoacuity was similar to that measured
in earlier lab-based preferential-looking and visual evoked potential
protocols; few infants younger than 2 months of age demonstrated
stereopsis although by 12 months, mean stereoacuity was 2.1 log sec (120
sec). A further improvement to 1.7 log sec (56 sec) was seen during
months 18 to 24, consistent with data obtained in an earlier operant
random dot protocol. Tolerance limits for normal ranged from
approximately 1000 sec at 6 months to 100 sec after 12 months. 
CONCLUSIONS: The infant random dot stereoacuity cards provide a simple,
quick, and portable preferential-looking test of random dot stereoacuity
for infants that has a high success rate and excellent concordance with
stereoacuity outcomes from laboratory-based protocols. 

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Of course a lot of inside terms in these abstracts, but you get the
point.
Abram Klooswyk


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