hirsch;180186 Wrote: > > Placebo's do work...both ways. Expectancy can eliminate a real > difference as easily as it can produce a false positive. >
We talked about this before on this forum - the hypthesis that the stress of blind tests reduced people's hearing abilities was termed "blinditis". It's quite a lot to buy - that people think they can hear a difference sighted or blind, but when blind they are stressed and can't actually hear it (even though they think they can), while when sighted they think they can and are correct. Implausible, but not impossible. It seems a difficult thing to rule out, but there may actually be a clever way... For example, first use a blind test to determine the sensitivity to, say, a difference in volume. Now do the same with a sighted test (the subjects know which is louder - because they can see the volume knobs - and are asked at what point they cease to be able to hear a difference). Now there are two possibilities - sensitivity was greater in the blind test, in which case the blinditis hypothesis is out, or it's greater in the sighted test. In the second case do another sighted test, but secretly reverse the knobs - so what the subjects think is louder is actually softer. Do this in the volume range between the two sensitivities, and see what the results are - do the subjects notice that something is wrong and the volumes have been swapped? If not, it's pretty clear it was bias effects that led them to think they could hear a difference, and therefore the blind test gave the correct result (i.e. no blinditis). If so, there is blinditis. I think refinements of this basic idea could pretty well rule this out or in. Of course this is to determine whether it's the blind part that causes the problem; if instead being tested in any way fundamentally changes our perceptions there's really very little that can be said. -- opaqueice ------------------------------------------------------------------------ opaqueice's Profile: http://forums.slimdevices.com/member.php?userid=4234 View this thread: http://forums.slimdevices.com/showthread.php?t=32352 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
