from II - PLASTICITY IN CHILDHOOD
Published online by Cambridge University Press: 05 January 2013
At birth, infants can see only large objects of high contrast located in the central visual field. Over the next half year, basic visual sensitivity improves dramatically. The infant begins to perceive the direction of moving objects and stereoscopic depth, and to integrate the features of objects and faces. Nevertheless, it takes until about 7 years of age for acuity and contrast sensitivity to become as acute as those of adults and into adolescence for some aspects of motion and face processing to reach adult levels of expertise.
An important developmental question is whether, and to what extent, the improvements in vision during normal development depend on normal visual experience. To find out, we have taken advantage of a natural experiment: children born with dense, central cataracts in both eyes that block all patterned visual input to the retina. The children are treated by surgically removing the cataractous lenses and fitting the eyes with compensatory contact lenses that allow the first focused patterned visual input to reach the retina. In the studies summarized in this chapter, the duration of deprivation – from birth until the fitting of contact lenses after surgery – ranged from just a few weeks to most of the first year of life. In other cases, the child began with apparently normal eyes but developed dense bilateral cataracts postnatally that blocked visual input. As in the congenital cases, the cataractous lenses were removed and the eyes fitted with contact lenses.
To save this book to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Find out more about the Kindle Personal Document Service.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.