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Overcoming the Perception Problem
item
post Oct 8 2012, 19:21
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I've noticed an increase in forum debate about the validity of transferring the credibility of ABX from the physical domain to perception testing. I'm wondering if anyone has found a way past this issue?

The purpose of blind testing is to subtract subjectivity from the effect of - for instance - a drug trial: to assess a medication's impact on a subject's physiology with interference from their psychology. But what about when the purpose of a test is subjective perception? How do we then subtract the effect of the method to arrive at a meaningful outcome?

While we would like to remove expectation bias from the equation, if the conditions under which this is done also change the perceptive state of the listener, the test is invalidated as surely as they would be by tissue sample contamination.

Recent large scale public experiments by Lotto Labs (http://www.lottolab.org/) demonstrated that perception acuity is dramatically altered by test conditions: for instance, that time contraction/dilation effects are experienced when exposed to colour fields. In one experiment, two groups were asked to perform an identical fine-grained visual acuity test. One group was pre-emptively 'manipulated' by filling in a questionnaire designed to lower their self-esteem. This 'less confident' group consistently performed worse on the test that the unmanipulated one: their acuity was significantly impaired by a subtle psychological 'tweak' that wasn't even in effect during the test.

It seems undeniable that the much grosser differences between the mental states of sighted and 'blind' listening - considered generously - cast serious doubt on the results thus obtained.

The harder line is that blind perception tests are a fundamental misappropriation of methodology. In psychology it's axiomatic that for many experiments the subject must be unaware of the nature of the test (see Milgram). If a normalised state is not cunningly contrived, results are at best only indicative of what a subject thinks they should do; at worst, entirely invalid.

Probing hearing, the point is that a test must not change the mental state of the listener.

The contrast between outcomes of sighted and listening tests is as stark as those demonstrating suggestibility (see McGurk), but giving too much credence to such an intrinsically unsound experimental approach (not spotting this difficulty) does no favours to our credibility at all.

The only way past the dilemma seems to be direct mechanical examination of the mind during 'normal' listening to explore why the experiences of sighted and unsighted listening differ. This seems to be an interesting question.

In the meantime, the idea that - despite the method problem - results from blind ABX are valid is at least supported by the majority of data derived from home testing, Audio DiffMaker et al, so we needn't get hung up on it.
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mzil
post Oct 16 2012, 04:39
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Please enlighten me. I am not a scientist nor have I had any training or study in this area. What positive and negative controls would one use to avoid this particular problem of bias I just mentioned? Please be specific, thanks.

This post has been edited by mzil: Oct 16 2012, 04:46
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krabapple
post Oct 16 2012, 22:28
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QUOTE (mzil @ Oct 15 2012, 23:39) *
Please enlighten me. I am not a scientist nor have I had any training or study in this area. What positive and negative controls would one use to avoid this particular problem of bias I just mentioned? Please be specific, thanks.


Start with two signals that are by any reasonable measure vastly different. Then slightly less different. Then slightly less different again. Repeat in increments until the listener starts 'guessing' or their 'bias toward no difference' kicks in.

Seriously, this is a non-issue for most listeners. In most cases I've read about where the DBT result was 'no support for the null H', the listener *believes* they hear a difference both before and *during the test* as well. In other cases they complain that the difference that they thought they heard 'sighted' suddenly seems harder to hear whne they're listening blind. In neither case is 'bias towards not hearing' a credible factor.

Btw, have you read Pio's HA sticky thread about blind listening tests?

http://www.hydrogenaudio.org/forums/index....showtopic=16295

This post has been edited by krabapple: Oct 16 2012, 22:39
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mzil
post Oct 17 2012, 00:30
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QUOTE (krabapple @ Oct 16 2012, 17:28) *
QUOTE (mzil @ Oct 15 2012, 23:39) *
Please enlighten me. I am not a scientist nor have I had any training or study in this area. What positive and negative controls would one use to avoid this particular problem of bias I just mentioned? Please be specific, thanks.


Start with two signals that are by any reasonable measure vastly different. Then slightly less different. Then slightly less different again. Repeat in increments until the listener starts 'guessing' or their 'bias toward no difference' kicks in.

Good example. Thanks. You then cherry pick the test subjects to get rid of the bad apples, I guess.

Can't say I recall ever reading of any DBT in the audio press which ever did this pre-screening you've just described, but I hope it or some similar procedure to preclude this particular bias is standard procedure in the academic world. [I can't edit my original post at this late date, however I didn't stress enough that the "mischievous" behavior of the listener may be (possibly) at a subconscious level. He/she would pass a lie detector test that they were "Doing their best", that is; they aren't "frauds".]

QUOTE
Seriously, this is a non-issue for most listeners.
So rather than applying the time consuming control you just described, we could simply ask potential participants if they might be biased on a conscious or subconscious level, instead. tongue.gif Ha-ha!

QUOTE
Btw, have you read Pio's HA sticky thread about blind listening tests?


Yes. Take Rule #1 for example:
QUOTE
Rule 1 : It is impossible to prove that something doesn't exists. The burden of the proof is on the side of the one pretending that a difference can be heard.
If you believe that a codec changes the sound, it is up to you to prove it, passing the test. Someone pretending that a codec is transparent can't prove anything.


So even though random results don't prove anything, which I agree is correct, you seem to think that statistical analysis may be applied to them?! Huh? That's what I don't get. If no firm conclusion can be drawn, one way or the other, how on earth can one describe the probability/certainty of "no evidence/proof found, at least in this instance". NOTHING was established in the first place and nothing was proven so how can you describe the certainty of this "nothing", this randomness, as a percentage?! For all we know the randomness is caused by problems with the test design, such as A, B, and/or C , all things which can be immediately ruled out if the results go the other way however (where the listener can successfully hear a difference most/all of the time), and we have no way of knowing the "percentage of likelihood" of problems such as A, B, or C. [But I do like that control you suggested for B. Bravo!]

This post has been edited by mzil: Oct 17 2012, 00:49
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- item   Overcoming the Perception Problem   Oct 8 2012, 19:21
- - Soap   You appear to be confused. Despite common shortha...   Oct 8 2012, 19:38
- - item   To rephrase: what, in any trial, is blind testing ...   Oct 8 2012, 19:52
|- - Soap   QUOTE (item @ Oct 8 2012, 14:52) To rephr...   Oct 8 2012, 19:59
|- - item   QUOTE (Soap @ Oct 8 2012, 19:59) QUOTE (i...   Oct 8 2012, 23:32
|- - item   Part of Beau Lotto's 'Public Perception pr...   Oct 9 2012, 00:30
||- - Porcus   QUOTE (item @ Oct 9 2012, 01:30) Part of ...   Oct 9 2012, 10:53
||- - item   QUOTE (Porcus @ Oct 9 2012, 10:53) You ca...   Oct 9 2012, 12:23
||- - Porcus   QUOTE (item @ Oct 9 2012, 13:23) This for...   Oct 9 2012, 16:04
|- - krabapple   QUOTE (item @ Oct 8 2012, 18:32) Partly, ...   Oct 9 2012, 03:51
|- - item   QUOTE (item @ Oct 8 2012, 18:32) Although...   Oct 9 2012, 11:14
- - DVDdoug   I just don't see how making a good scientific ...   Oct 9 2012, 00:59
- - greynol   @item: Perhaps you could share with us a little ab...   Oct 9 2012, 04:54
|- - Porcus   QUOTE (greynol @ Oct 9 2012, 05:54) a fai...   Oct 9 2012, 09:57
|- - item   QUOTE (greynol @ Oct 9 2012, 04:54) @item...   Oct 9 2012, 11:42
|- - 2Bdecided   QUOTE (item @ Oct 9 2012, 11:42) Positive...   Oct 9 2012, 14:15
||- - item   QUOTE (2Bdecided @ Oct 9 2012, 14:15) QUO...   Oct 9 2012, 14:37
||- - 2Bdecided   QUOTE (item @ Oct 9 2012, 14:37) Deprived...   Oct 9 2012, 17:43
|||- - item   Sorry - been away, but lots of noise (most - fasci...   Oct 19 2012, 17:34
||- - dhromed   QUOTE (item @ Oct 9 2012, 15:37) 'Kno...   Oct 9 2012, 19:11
|- - greynol   QUOTE (item @ Oct 9 2012, 03:42) QUOTE (g...   Oct 9 2012, 22:07
|- - item   QUOTE (greynol @ Oct 9 2012, 22:07) @item...   Oct 19 2012, 18:33
- - hlloyge   The only people I know of to shun DBT method of te...   Oct 9 2012, 12:35
|- - item   QUOTE (hlloyge @ Oct 9 2012, 12:35) The o...   Oct 9 2012, 13:25
|- - hlloyge   QUOTE (item @ Oct 9 2012, 14:25) The sole...   Oct 9 2012, 13:54
||- - item   QUOTE (hlloyge @ Oct 9 2012, 13:54) The o...   Oct 9 2012, 14:09
|- - Canar   QUOTE (item @ Oct 9 2012, 05:25) I think ...   Oct 9 2012, 17:09
|- - krabapple   QUOTE (item @ Oct 9 2012, 08:25) The sole...   Oct 10 2012, 01:25
|- - item   QUOTE (krabapple @ Oct 10 2012, 01:25) QU...   Oct 19 2012, 18:45
|- - Porcus   QUOTE (item @ Oct 19 2012, 19:45) QUOTE (...   Oct 19 2012, 19:22
|- - 2Bdecided   QUOTE (item @ Oct 19 2012, 18:45) Certain...   Oct 22 2012, 12:53
- - aethelberht   What I can perhaps maybe possibly gather from your...   Oct 9 2012, 13:17
|- - item   QUOTE (aethelberht @ Oct 9 2012, 13:17) W...   Oct 9 2012, 14:01
|- - aethelberht   "A negative means - equally - either a) the t...   Oct 9 2012, 14:14
|- - Arnold B. Krueger   QUOTE (item @ Oct 9 2012, 09:01) DBT is d...   Oct 9 2012, 14:53
|- - hlloyge   QUOTE (item @ Oct 9 2012, 15:01) Abstract...   Oct 10 2012, 21:04
|- - Porcus   QUOTE (hlloyge @ Oct 10 2012, 22:04) If y...   Oct 11 2012, 14:20
|- - hlloyge   QUOTE (Porcus @ Oct 11 2012, 15:20) Ehem ...   Oct 12 2012, 14:26
|- - Porcus   QUOTE (hlloyge @ Oct 12 2012, 15:26) QUOT...   Oct 12 2012, 15:04
|- - hlloyge   QUOTE (Porcus @ Oct 12 2012, 16:04) Not n...   Oct 12 2012, 22:14
|- - greynol   QUOTE (hlloyge @ Oct 12 2012, 14:14) I am...   Oct 13 2012, 14:25
|- - hlloyge   QUOTE (greynol @ Oct 13 2012, 15:25) QUOT...   Oct 14 2012, 13:35
|- - Porcus   QUOTE (hlloyge @ Oct 14 2012, 14:35) Yes,...   Oct 14 2012, 23:31
|- - hlloyge   QUOTE (Porcus @ Oct 15 2012, 00:31) QUOTE...   Oct 16 2012, 09:54
- - Porcus   While I certainly agree that putting humans in a l...   Oct 10 2012, 13:09
- - 2Bdecided   It's like The Princess and the Pea. Audiophile...   Oct 11 2012, 11:58
- - skamp   If ABXing negatively alters one's ability to h...   Oct 11 2012, 14:28
|- - krabapple   QUOTE (skamp @ Oct 11 2012, 09:28) If ABX...   Oct 11 2012, 18:24
|- - mzil   QUOTE (krabapple @ Oct 11 2012, 13:24) QU...   Oct 15 2012, 17:14
|- - krabapple   You're right that different terms apply when w...   Oct 15 2012, 20:51
- - greynol   I believe our skeptic has flown the coop.   Oct 11 2012, 16:17
- - dhromed   Not everyone is as much a netizen as most of us. P...   Oct 11 2012, 17:05
- - googlebot   While the OP's reasoning and claimed inference...   Oct 11 2012, 21:44
|- - [JAZ]   QUOTE (googlebot @ Oct 11 2012, 22:44) Do...   Oct 11 2012, 22:37
||- - bandpass   QUOTE ([JAZ] @ Oct 11 2012, 22:37...   Oct 12 2012, 06:44
|- - sld   QUOTE (googlebot @ Oct 12 2012, 04:44) Lo...   Oct 12 2012, 03:38
|- - krabapple   QUOTE (googlebot @ Oct 11 2012, 16:44) Wh...   Oct 12 2012, 06:59
||- - googlebot   QUOTE (krabapple @ Oct 12 2012, 07:59) Ex...   Oct 12 2012, 21:44
||- - Nick.C   QUOTE (googlebot @ Oct 12 2012, 21:44) Th...   Oct 12 2012, 21:51
|||- - googlebot   QUOTE (Nick.C @ Oct 12 2012, 22:51) Is th...   Oct 12 2012, 21:58
|||- - Nick.C   QUOTE (googlebot @ Oct 12 2012, 21:58) Ye...   Oct 12 2012, 22:21
|||- - googlebot   I do not see how calling the phenomenon "prec...   Oct 12 2012, 23:43
||- - krabapple   QUOTE (googlebot @ Oct 12 2012, 16:44) QU...   Oct 13 2012, 22:05
|- - 2Bdecided   @Porcus: QUOTE (googlebot @ Oct 11 2012, 21...   Oct 12 2012, 10:08
|- - Arnold B. Krueger   QUOTE (googlebot @ Oct 11 2012, 16:44) Co...   Oct 16 2012, 15:51
- - greynol   I would be careful not to limit the word perceive....   Oct 11 2012, 22:58
- - greynol   I extract all the joy I could ever need from simpl...   Oct 12 2012, 06:11
- - Porcus   Among my friends, we have been blind testing ... h...   Oct 12 2012, 09:30
- - dhromed   But is there a problem?   Oct 12 2012, 22:12
- - AndyH-ha   The sighted test difference is not coming from the...   Oct 13 2012, 03:32
|- - greynol   QUOTE (AndyH-ha @ Oct 12 2012, 19:32...   Oct 13 2012, 14:16
- - Nick.C   @googlebot: You are now allowing the results to be...   Oct 13 2012, 09:43
- - 2Bdecided   I think Googlebot is making a valid philosophical ...   Oct 15 2012, 12:20
|- - pisymbol   QUOTE (2Bdecided @ Oct 15 2012, 07:20) I ...   Oct 15 2012, 13:48
- - skamp   QUOTE (mzil @ Oct 15 2012, 18:14) B. The ...   Oct 15 2012, 22:49
|- - krabapple   QUOTE (skamp @ Oct 15 2012, 17:49) What g...   Oct 16 2012, 03:58
- - greynol   There are ways of cheating to get positive ABX res...   Oct 15 2012, 22:57
- - mzil   [Trying to bring this back on topic] There is not...   Oct 16 2012, 04:32
|- - Woodinville   QUOTE (mzil @ Oct 15 2012, 20:32) [Trying...   Oct 16 2012, 04:33
|- - Porcus   QUOTE (mzil @ Oct 16 2012, 05:32) Here...   Oct 16 2012, 06:19
- - mzil   Please enlighten me. I am not a scientist nor have...   Oct 16 2012, 04:39
|- - krabapple   QUOTE (mzil @ Oct 15 2012, 23:39) Please ...   Oct 16 2012, 22:28
|- - mzil   QUOTE (krabapple @ Oct 16 2012, 17:28) QU...   Oct 17 2012, 00:30
|- - saratoga   QUOTE (mzil @ Oct 16 2012, 19:30) So even...   Oct 17 2012, 03:03
||- - mzil   QUOTE (saratoga @ Oct 16 2012, 22:03) QUO...   Oct 17 2012, 05:35
||- - saratoga   QUOTE (mzil @ Oct 17 2012, 00:35) Sorry, ...   Oct 17 2012, 05:43
|- - krabapple   QUOTE (mzil @ Oct 16 2012, 19:30) QUOTE (...   Oct 17 2012, 04:53
||- - mzil   QUOTE (krabapple @ Oct 16 2012, 23:53) QU...   Oct 17 2012, 06:36
||- - mzil   QUOTE (krabapple @ Oct 16 2012, 23:53) Do...   Oct 17 2012, 07:22
|||- - mzil   QUOTE (mzil @ Oct 17 2012, 02:22) QUOTE (...   Oct 18 2012, 19:16
||- - Arnold B. Krueger   QUOTE (krabapple @ Oct 16 2012, 23:53) Do...   Oct 18 2012, 14:04
|- - Porcus   QUOTE (mzil @ Oct 17 2012, 01:30) QUOTE R...   Oct 17 2012, 18:51
- - knutinh   Self-reporting about ones mental state surely carr...   Oct 16 2012, 21:02
- - greynol   Let me get this straight, the subconscious mind is...   Oct 17 2012, 05:28
- - mzil   Thanks, Porcus. I'll check it out.   Oct 17 2012, 20:14
- - krabapple   It's best to be careful drawing conclusions fr...   Oct 19 2012, 17:53
|- - 2Bdecided   QUOTE (krabapple @ Oct 19 2012, 17:53) It...   Oct 22 2012, 12:49
- - AndyH-ha   I could be missing the point, or dozens of them, b...   Oct 19 2012, 20:56
|- - Arnold B. Krueger   QUOTE (AndyH-ha @ Oct 19 2012, 15:56...   Oct 19 2012, 21:30
- - AndyH-ha   My point was not that many reported tests involve ...   Oct 19 2012, 22:31
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