Effect of an intervening screen on accommodation to a distant object

Stark, Lawrence R. & Atchison, David A. (1998) Effect of an intervening screen on accommodation to a distant object. Clinical and Experimental Optometry, 81(3), pp. 119-130.


Background: An intervening screen has been suggested to induce an inward shift of accommodation when viewing a distant object. This is an example of the Mandelbaum effect. However, there have been no objective measures of the magnitude of this effect in this particular situation. Methods: Accommodation was recorded with an infra-red optometer, while subjects (n = 16) viewed a distant letter target with or without an intervening screen. Screens were placed near the individual dark focus distance or at 50 cm. In a second experiment the contrast of the distant target was varied and subjects (n = 5) viewed the target directly or through a screen placed near the individual dark focus distance. Results: In the main experiment, the Mandelbaum effect was not significantly different from zero and was less than 0.5 D in every subject. In addition, accommodation was not more variable when viewing through the screen. However, it may be that some subjects do demonstrate a Mandelbaum effect while others do not. The individual dark focus level did not predict a susceptibility to the Mandelbaum effect for a screen at the dark focus. Subjects reported their perceptions of the tasks and some noted changes in the perceived distances of objects when viewing through a screen. In the second experiment, the Mandelbaum effect (< 0.6 D) did not vary with distant target contrast. Conclusions: When viewing a distant object through a screen there is a small (< 0.6 D) or negligible inward shift of accommodation.

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ID Code: 5174
Item Type: Journal Article
Refereed: Yes
Additional URLs:
Keywords: accommodation, conflicting stimuli, contrast, Mandelbaum effect, motor vehicles, perceived distance
ISSN: 0816-4622
Subjects: Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > OPTOMETRY AND OPHTHALMOLOGY (111300)
Divisions: Current > QUT Faculties and Divisions > Faculty of Health
Current > Institutes > Institute of Health and Biomedical Innovation
Copyright Owner: Copyright 1998 Optometrists Association Australia
Copyright Statement: The contents of this journal from 1998 to 2005 can be freely accessed online via the journal’s web page (see link).
Deposited On: 15 Nov 2006 00:00
Last Modified: 09 Jun 2010 12:34

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