Thursday, August 13, 2009

Chapter 4 of Perplexities: Human Echolocation

As you may know, I'm writing a book about the inaccuracy (in my view) of people's judgments about their stream of conscious experience (tentative title: Perplexities of Consciousness). Last winter and spring I posted drafts of six of the eight chapters (available from my academic homepage). In early summer, I got distracted with a trip to Australia and a few other things, but now I'm back in the saddle. So here's Chapter 4, "Human Echolocation", co-authored with psychologist Michael S. Gordon.

Most people, when asked explicitly, will deny that they can detect the properties of silent objects, such as shape, texture, and distance, using echoic information about how sound is reflected or otherwise modified by those objects. They'll deny, that is, that they can echolocate. It turns out, however, that people are surprisingly good at echolocation (if not as good as bats or dolphins). We are mistaken not just about our sensory capacities but also about our sensory experiences. There's "something it's like" to echolocate; echolocation has a kind of auditory phenomenology. You can hear, for example, the proximity of a wall as you approach it eyes closed; you can hear the wadded softness of a blanket as you speak into it; and, generally speaking, though they tend to deny it, people have a pervasive auditory echoic phenomenology of their environments and objects nearby.


  1. Can't wait to read the book. The only thought I have on the abstract is a question: whether there is information of the kind that is phenomenally available only when we become specially trained or attuned to it. Playing with an orchestra, combined with a study of sound recording, gave me the ability to hear with a good degree of distinctness not only the separate instruments - and in the case of drums, the separate tracks - but the nature of the acoustic environment or digital processing of each instrument or track (gating, reverberation, chorusing, compression). I have come to find out that people do not naturally hear just about any of this even though they are standard perceivers of their favorite music types or the overall unique sound of their favorite band (or brass quartet) that employ this sort of intentional design. But for me, the sound engineering that went into a recording is often a large part of my enjoyment of listening to a musical piece. I can't help but wonder if this is an analog to echolocation. Perhaps there is not something it is like to echolocate until only after one learns how to echolocate in a phenomenal way. I would not have denied it. This reminds me of another question an old wise man once brought to my attention: are many human mammals more like unconscious squirrels gathering nuts? (To explain, I am not apart of any academic institution, which provides me the opportunity to wonder in many different directions.)

  2. Hi Michael! I can't entirely rule out the possibility you describe, but it seems to me less likely than that we actually do have a more or less constant echoic auditory experience of our environment. Among my reasons for thinking the latter is the fact that in some cases echoic differences in experience are very obvious (e.g., singing in the shower vs. outside); and it seems to me introspectively and retrospectively plausible to suppose that there are somewhat less obvious but more pervasive counterparts to those obvious experiences. More detail on this in the chapter, of course!

  3. Ok. This seems to be a very interesting way to try to get at this What It Is Like stuff. I need to read the chapter. My first thought to your reply is that yes, there is something it is like to be me at time t while singing in my shower, which differs from what it is like being me at time t2 while singing outside. And I would attribute this difference to the change in my acoustical environment. This is perhaps similar to an average music listener telling the difference between a recording of a live performance and one in the studio. But even here there would need to be background training, leading to special attunement. I wonder if most of the acoustical aspects of What It Is Like to Be is representative of unconscious echolocation information, while not consciously representative as this type of information until special training. Echolocation, functionally construed, would therefore be primarily an unconscious phenomena.

  4. Fascinating subject matter, and intriguing reflections on it!

    Noticed a typo on p. 13: "And yet they still they are, we think, pretty badly mistaken."

  5. Thanks for catching the typo, David.

    Michael: That people don't know that the differences in their experience are due to echoic input is still, I think, consistent with their experiencing auditory information echoically. A possible analogy is timbre: People hear timbrel differences even if they don't know that it's differences in the overtone series they are responding to.

  6. Sorry, but this comment is actually for the first chapter on the color content of our dreams, which I only now started to read (and thought it was extremely interesting).

    The following seems to me like a way to determine whether a dream is in colour or black and white. This takes from the lucid dreaming studies of Stephen LaBerge and Lynn Nagel. They had an agreed-upon signal that the dreamer could give the researcher to indicate that they had entered a lucid dream. For example, moving the eyes smoothly up and down, which is clearly picked up on the EOG.

    Could you not do the same thing for a dreamer to indicate the color quality of their dream? You would have one signal for color and another for black and white (and maybe one for neither?). This way the dreamer could indicate the color content of their dream WHILE they are dreaming. Or at least this would indicate the color content of lucid dreams.

    I admit I'm not very familiar with the dreaming literature, having got much of what I know from Jeff Warren's book, The Head Trip: Adventures on the Wheel of Consciousness--which I read as I'm currently a grad student sharing an office with Jeff Warren's brother.

  7. Interesting thought, Andreas! I'd like to hear the results of any such experiment.

    Although the results would be suggestive, they wouldn't, I think, be quite decisive. For one thing, lucid dreams might differ from other dreams. But also, even concurrent introspection of coloration may be subject to confusions and illusions of various sorts, as I think is concurrent introspection of imagery (as I argued in a 2002 article and Ch. 3 of my book in draft) and concurrent introspection of sensory visual experience (as I argued in a 2008 article and Ch. 7 of my book in draft).

  8. I will need to track down those articles (I might already have them, but just haven't gotten around to read them), as well as the rest of the book, which I am excited to do. I'm interested to see how people could be confused about not just their imagery, but their own sensory visual experience--it seems to me that dreams are more like our sensory visual experience than our mental imagery.

    Hmn, as far as that experiment goes, I wish my lab (cognitive psychology, a focus on memory) was setup to do it. Maybe when I'm drifting around a conference I'll hunt down someone involved in this kind of work and suggest it to them. I would also be interested to know the results.

  9. Sure, Andreas, keep me posted. On whether dreams are percept-like or image-like I recommend Jonathan Ichikawa.

  10. Most interesting; I look forward to reading this closer. But, already, I'm not sure I can be entirely convinced that the experience you describe isn't just realy good hearing, as opposed to some mysterious sixth sense we're calling "echolocation."

    One argument for not calling the experience -- which I do not deny exists...I've always been fascinated by that sensation; thanks for putting it on paper! -- "echolocation" is that other senses (touch, hearing, taste, smell, and sight) can each largely work all by itself, i.e., when other senses are shut off. For instance, if you close your eyes, you can still taste a strawberry (though admittedly your sense of taste may not be as accurate, given that sight doesn't give visual confirmation of the oral perception). The same seems to be true of other senses. But all of your examples of echolocation (on my quick reading) rely on sound (echo) or touch (micro-vibrations of background soundwaves on skin?). I can't imagine what ecolocation would feel like *without* referring to other senses.

    So perhaps Nagel can still be right: we can't know echolocation (assumed to be a mysterious sixth sense and not just an extension of current senses) without imagining it through the lens of another sense faculty. This either means that echolocation really is just an extension of some current sense or that we truly are unable to feel like a bat (to perceive or even imagine echolocation), much as we're unable to imagine truly new things that don't trade off already-known ideas/perceptions. Either way, that speaks against your argument that we can and already do experience echolocation.

    You could, at this point, bite the bullet and say that echolocation is just really good hearing or tactile perception; but this again defeats the surprising twist of your argument, which is that we are able to do something that we didn't know or think we could do.

    Or you'd need to explain why echolocation should be different from the other senses in this respect, and I see an obvious solution to this. The simpler answer is that "echolocation" is just a name for a very accurate range of hearing or touch.

    However...perhaps there's an argument that senses are all related and only arbitrarily differentiated. Consider that what we see and what we hear are merely energy waves at different frequencies. Well, touch too is merely the detection of a different range in wavelengths, given that all that is vibrates at the atomic level (and that we never really "touch" an object given atomic forces that prevent atoms from physically contacting each other, which, if overcome, literally produces the energy of an atom bomb). And taste and smell are the translation of yet other ranges of vibrational matter. (Ok, maybe this is a weak argument.)

    Anyway, not that it wouldn't be cool to show everyone that we really have this extra sense that we didn't know we had -- I'd love for that to happen -- it's just a nagging worry I have about using that phenomenology to argue that humans already perceive echolocation. Will re-read your paper to make sure I didn't miss your consideration of this problem in the paper...

  11. Anon 9:03 here again -

    And to be clear, what I understand to be echolocation is some weird perception that you feel inside your body -- maybe it's supposed to be felt in your soul -- that communicates detailed information about some physical object in your vicinity. This is analogous to a battleship's radar or a bat's sonar.

    What I haven't looked into yet, though, is whether the "ping" emitted by a ship or a bat is considered to just be a sound of a certain frequency, in which case we can make an even stronger case that echolocation is really just enhanced auditory perception. Note that the sound doesn't need to be created by an animal's mouth; crickets, for instance, chirp by rubbing their legs. I believe dolphins or other creatures have a special organ to emit these sounds? (I need to look that up too...)

  12. I said in 9:03: "...and I see an obvious solution to this."

    I meant" "I see *no* obvious solution to this." And I see other typos. Can't type and drink at the same time...

  13. Thanks for the thoughtful comments, anon 9:03 &c! I do think echolocation is an aspect of hearing, though I don't think it involves any special degree of accuracy -- even pretty dim hearing has echoic aspects that we can and do take advantage of, on my (and Mike's) view.

    Perhaps acknowledging this takes out some of the fun of the chapter, which one might think -- perhaps you did think -- promised to argue that we have a mysterious 6th sense no one knows anything about. That promise I cannot fulfill. But I do think that there is an aspect of our *auditory* experience that we know very little about, rarely appreciate, and tend to actively deny when questioned. That is -- I hope -- still surprising enough to be interesting.