Subject: Re: Implicit human echolocation From: "Ewan A. Macpherson" <emacpher@xxxxxxxx> Date: Thu, 31 May 2007 11:26:57 -0500 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>On 31 May 2007 at 9:33, Bob Masta wrote: > On 30 May 2007 at 9:31, Bruno L. Giordano wrote: > > An improbable single-trial experiment could address this question: > > blindfolded participants are asked to walk along a path, as long as > they > > wish. They wouldn't be informed that a wall is obstructing the path. > Harry Erwin has mentioned Griffin's "Listening in the Dark". > As I recall, this book discusses an experiement almost > identical to the one you propose. I believe Griffin used a > moveable barrier in a straight hallway, set to a random > distance down the hall without the knowledge of the > blindfolded subject. The subject knew he would encounter > the barrier, but not where/when. > > I think the experiment was repeated with a microphone > on a trolley in place of the subject, and the subject would > then listen through headphones as the trolley was moved > down the hall. That experiment is indeed described by Griffin (at least in "Echoes of Bats and Men"), but was done by Supa, Cotzin & Dallenbach (1944): "Facial vision", the perception of obstacles by the blind. Am.J.Psych. 57:133-183. Blind subjects were able to detect the barrier equally well by means of the recordings or when their faces were covered with a felt veil, thus disproving the "facial" part. -- Ewan Macpherson, Ph.D. <emacpher@xxxxxxxx> Research Investigator, Central Systems Laboratory Kresge Hearing Research Institute, U. Mich. http://www-personal.umich.edu/~emacpher