Locke Revisited: What would a baby born with cataracts see if visual stimulation was restored later

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Locke Revisited What would a baby born with
cataracts see if visual stimulation was restored
later in life?
Ron Boothe Emory University
Colloquium Presented at Department of
Psychology University of Puget Sound Tacoma,
Washington November 15, 2002
(text of the talk is on the Notes Pages)
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The philosopher John Locke, writing in the 17th
Century, discussed the following question
Would a person who had been born blind, if he
suddenly became able to see, be able to recognize
shapes such as a cube or a sphere by sight?
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Locke posed this question in the context of broad
philosophical issues involving theories of
epistemologyNativism versus Empiricism
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In the intervening millennia, these kinds of
questions have continued to fascinate
philosophers, psychologists and neuroscientists

• Nativism versus Empiricism
• Nature versus Nurture
• Genes versus the Environment

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Theoretical Framework Developmental problem
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Experimental Paradigm
birth
later in life
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Case Studies
Case Studies von Senden 1932 Gregory
1963 Valvo 1971 Oliver Sacks 1993
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There are serious limitations to the conclusions
that can be drawn from studies of humans.Many
of those limitations can be overcome by utilizing
an appropriate animal model.It has been
established that monkeys provide an ideal model
for studies addressing questions about
development of visual perception.
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Adult monkeys and adult humans are virtually
identical in terms of basic visual
functions.The biology of the eyeball and the
portions of the brain that do initial processing
of visual information are also highly
similar.The time courses for development of
visual function in infant humans and monkeys can
be related to one another.
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Preferential Looking
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View through the Preferential Looking Peephole
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Operant methods
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Postnatal ages can be related by the 4 to 1
(weeks to months) rule
Boothe et al 1985
If a particular developmental events happens at a
particular postnatal age in weeks in the
monkey, It happens at the same age in months in
the human. Human-equivalent ages can be used
to express developmental events in the monkey in
terms of the age at which the event likely occurs
in human.
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Development of Acuity in Humans and Monkeys
Teller 1981
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Development of Stereo in Humans and Monkeys
ODell and Boothe 1997
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Monkey Models for Studying Treatments of
Infantile Cataracts
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Occlusion regimens
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Purpose of study
We raised monkeys with bilateral occlusion for
three weeks (roughly equivalent to three months
in humans) after birth and subsequently assessed
the development of visual acuity. We carried
out these studies for the purpose of conducting a
direct test of whether acuity development depends
on postnatal visual stimulation or proceeds
following an innate program even in the absence
of stimulation.
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Predicted Outcomes
adult
Perceptual Level
none
birth
3 weeks
Age
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Plot from 3 weeks
M Goodman, Doctoral Dissertation, Emory
University, 2002
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Plot from birth