Subject: Re: Implicit human echolocation From: Peter Lennox <P.Lennox@xxxxxxxx> Date: Fri, 1 Jun 2007 08:54:53 +0100 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>Barry, I'm confused, though suspect the confusion lies in the way we each use the word "perception" - you state that echolocation is more than 'just' perception, and I'm not sure what you mean. This may be, though, because I haven't found anything that humans do that isn't perception. In other words, for me, cognition is part of perception, rather than being subserved by perception. so in this context, something one 'knows' through being steeped in a culture is simply one kind of perception, rather than a qualitatively different activity. In other words, for me, perception isn't too closely identified with sensation - it's not just 'sense-perception'. Am I using the term radically differently from others' usage? regards ppl Dr. Peter Lennox S.P.A.R.G. Signal Processing Applications Research Group University of Derby http://sparg.derby.ac.uk Int. tel: 3155 >>> Barry Blesser <bblesser@xxxxxxxx> 05/31/07 10:28 PM >>> Hi, Having followed the dialog on human echolocation, I would like to introduce an alternative (contrary) perspective on the subject. There are many reports over the centuries describing people doing echolocation. Diderot, the French philosopher, first observed this in the 18th century. In the 1930s it was called face vision. Following WWII, echolocation among those with a visual disability was a hot and confrontational topic. There is an extensive literature on the subject. Clearly, some human being can use this ability to "see" with their ears. When I was teaching at MIT in the 1960s, I often demonstrated the effect by having a random student walk slowly towards a wall with eyes closed and instructed to stop 6" before hitting the wall. Almost everyone could do it on the first try, and everyone could to do it after several attempts. At least that was true in the acoustics of the older MIT classrooms (dating from the early 20th century and highly reverberant). This raises the question of what are people doing? I am confident that everyone can "hear" the required physical cues. If one recorded the background noise at the center of a hall and also close to the wall surface, I believe that everyone would perform very well in an ABX or same-different paradigm. Detecting (discriminating) auditory cues is only part of the story. The second part is for the listener to create (invent) a cognitive strategy that transforms perceptible cues into a physical reality, in this case, proximity to the wall. To do echolocation in a real setting, a listen must have a cognitive strategy. And that strategy could have been created years ago or only during the experiment. Some blind individual have evolved an elegant strategy, as explained by Dan Kish, the blind teacher of orientation and mobility. But other blind individual who are taught to use the cane never learned to use hearing for navigation. They may not have a strategy. My objection to the proposed research is the issue of what question is being asked and then answered. If the central issue is a cognitive strategy, which involved labeling, pattern recognition, and auditory memory, then the experiment only reveals who has, and who has not, created such a strategy. The answer is dependent on life style, personality, local culture, sensory attitudes, intellectual curiosity, and so on. I have no doubt that some people do not know that such a strategy could exist. Others may know that it exists but never attended to it. In my case, I have a self-taught but primitive strategy. Strictly speaking, echolocation is far more than a perceptual issue. When I examined this subject while researching for my book, Spaces Speak, Are You Listening, discussed mostly in Chapter 2 and extensive references, I came to the conclusion, that we need to introduce the concept of cultural acoustics, which is of course difficult to study and seldom reproducible. But this limitation does not make the phenomenon any less real. If we only study questions that match our convenient (scientific) paradigms, then we are distorting the phenomenon with an intellectual dishonesty. There is no evidence that echolocation is only a perceptual ability. And that is my two sense, Barry ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________