Path: utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!olivea!decwrl!asylum!osc!jgk
From: jgk@osc.COM (Joe Keane)
Newsgroups: sci.bio
Subject: Re: Speed of human eye?
Summary: About 20 frames per second.
Keywords: brightness
Message-ID: <4503@osc.COM>
Date: 12 Feb 91 19:41:18 GMT
References: <1991Feb5.080035.10362@ousrvr.oulu.fi> <1436@tau.sm.luth.se> <LFK.91Feb11094035@eastman1.mit.edu> <3400@ac.dal.ca>
Reply-To: jgk@osc.COM (Joe Keane)
Organization: Versant Object Technology, Menlo Park, CA
Lines: 6

There is an experiment which determines this.  You shine a light of given
intensity for some interval and have a subject determine the subjective
brightness.  For a long interval this depends only on the intensity, while for
a short interval it depends on the intensity integrated over time.  By
graphing this you can determine the `integrating time' of the eye.  I don't
have an exact number, but i remember it being around 50 ms.