Document Detail

Infant light adaptation shows Weber's law at photopic illuminances.
MedLine Citation:
PMID:  11164451     Owner:  NLM     Status:  MEDLINE    
In the present study we investigate the dependence of photopic contrast thresholds on retinal illuminance in infants and adults. Contrast thresholds were measured at five retinal illuminances between about 6 and about 20,000 Td in subjects in both age groups. The forced-choice preferential looking technique was used in 3-month-old infants, and standard forced-choice techniques were used in adults. The stimulus was a 0.25 cy/deg squarewave grating phase alternated at 6 Hz. Infants' contrast thresholds were more than two log units higher than those of adults at all retinal illuminances. Contrast thresholds had a similar dependence on retinal illuminance in both infants and adults. For both age groups, contrast thresholds initially decreased with increasing retinal illuminance. However, at both ages, above a critical illuminance of about 200 Td, contrast thresholds remained constant, following Weber's law. Thus a vertical shift was sufficient to bring the two data sets into correspondence. In the context of a two-site model of light adaptation, our results imply that infants' elevated contrast thresholds cannot be explained solely on the basis of photoreceptoral immaturities. Later physiological immaturities must also limit infants' photopic contrast thresholds.
T A Rasengane; J Palmer; D Y Teller
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Vision research     Volume:  41     ISSN:  0042-6989     ISO Abbreviation:  Vision Res.     Publication Date:  2001 Feb 
Date Detail:
Created Date:  2001-02-21     Completed Date:  2001-03-01     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0417402     Medline TA:  Vision Res     Country:  England    
Other Details:
Languages:  eng     Pagination:  359-73     Citation Subset:  IM    
Department of Psychology, Box 351525, University of Washington, Seattle, WA 98195-1525, USA.
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Adaptation, Ocular / physiology*
Contrast Sensitivity / physiology*
Differential Threshold
Least-Squares Analysis
Linear Models
Grant Support

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

Previous Document:  Perceptual learning of apparent motion mediated through ON- and OFF-pathways in human vision.
Next Document:  The role of chromatic contrast and luminance polarity in stereoscopic segmentation.