Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!HOGG.CC.UOREGON.EDU!jqj
From: jqj@HOGG.CC.UOREGON.EDU
Newsgroups: comp.protocols.tcp-ip
Subject: Re: Subliminal (RFC1097)
Message-ID: <8904251341.AA04991@hogg.cc.uoregon.edu>
Date: 25 Apr 89 13:41:55 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 23


	What sort of hardware is needed to implement this? The 1/60
	second update rate of standard CRTs is too slow for subliminal
	messages, even ignoring considerations of phosphor decay rates.
	Do you need some sort of RS232-able tachistoscope to get the
	required ~2ms display time?
A standard vector CRT with a reasonably flexible controller should do
the trick.  HP makes such a beast, for instance.  If you keep the
display list very short and tell the controller to scan once only,
you may be able to achieve 2ms display time.  In a perception lab
with which I am associated we routinely get ~10ms temporal accuracy,
more limited by the cpu clock than by the display.

Note, however, that since you must draw characters the text of your 
message must be kept short.  A reasonable upper bound would be 2 
characters.  Thus, the subliminal message "IP" is doable, but "OSI" 
probably is not.

More seriously, but not appropriate to this list:  if anyone knows
of any raster display hardware capable of < 10ms temporal resolution
please send me email.  We are interested in buying...  Our T-scope
controller is a networked PC (spry.psych.uoregon.edu), but the stimuli
still have to be inserted in the fields manually.