Can I reinforce what Michael MacAskill says about sampling and display
rates?
Apart from the immense technical difficulty of knowing exactly when a
stimulus is displayed in relation to a data sample (unless you use a system
such as the CRS ViSaGe, which guarantees explicit synchronization), it is
utterly pointless to measure latencies at msec or sub-msec resolution when
the intrinsic brain-generated variability is so enormous.
The solution is to make lots of observations, and get proper estimates of
the stochastics; a 100 Hz frame rate synchronized to 10 msec samples is
then fine. LCD displays are hopeless, not just because of not knowing at
what time any particular pixel is displayed, but because of the way in
which luminances and colours depend on viewing angle.
Roger
--
Professor R H S Carpenter MA PhD ScD
University of Cambridge
Department of Physiology, Development and Neuroscience,
Cambridge CB2 3EG
Tel +44 1223 333886 Fax +44 1223 333840
http://www.cudos.ac.uk/roger
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