Monday, February 19, 2007

Suppose you're not Joshua.

Okay so here's a question that I've only thought a little about, but it seems important and underexplored in the philosophy of perception (not my AOS, so it might not in fact be underexplored). First, suppose you are not Joshua. Provided this supposition obtains, you believe that there are illusions. Cases of visual illusions abound. And illusions differ from hallucinations. What I wonder is to what extent there are cases of illusion for non-visual sensory modalities. I take it that examples of hallucinations are fairly easy to come by in many cases, but illusions seem to be much more rare. So are there compelling examples of haptic, kinesthetic, auditory, gustatory, or olfactory illusions?


Blogger Joshua said...

I am not sure what counts as an illusion. But, sometimes I have experiences as if I am smelling a particular thing when there are no such things around. This is often associated with a vivid memory of some event.

Similarly, when I am eating one kind of thing but expecting something else, I hav strange gustatory sensations.

I suppose the most compelling example I can come up is an auditory example. Sometimes, when a single tone is played in my presence for a long period of time, it sounds as if the tone is changing. There is a wablyness to the noise.

Have you tried to look up cases that have been been studied acedemically? I would be interested to hear about any cases that you might find.

Finally, and for the record, I do think there are cases of visual illusions. there are definitely illusions involving size, for example. I am just uncertain about whether these color examples are in fact illusions.

8:12 AM  
Blogger Chris Tillman said...

I was just messing with you in asking all to suppose they are not Joshua. I am particularly interested in whether there are olfactory illusions. I am afraid your case is a case of hallucination. And apparently there are such cases. I understand that people about to suffer a stroke hallucinate the smell of burnt toast, for instance. I don't have a clear account of the hallucination/illusion distinction, but here are some rough remarks. The stick partially submerged causes the illusion that the stick is bent. You are not hallucinating that. You hallucinate when something seems to you to be the case but there is no external cause for your seeming. I am not confident that this could be plausibly strengthened to a biconditional. Illusion seems to involve getting things partly right and partly wrong, where hallucination involves getting things wholly wrong. I know this is horribly imprecise, but the ideas seem serviceable.

I've found some research on these. I'll post about them soon.

8:49 AM  
Blogger Joshua said...

I think that the situation involving a single, steady tone that sounds like an oscillating tone might still be a case of illusion.

I am not sure though. Here is one strange thing. We tend to think that if one sound wave interferes with another before we experience it, there is a new sound produced and our perception is accurate. However, we tend to think taht if one light wave interferes with another before being experienced by us, then our perception is innacurate and we are involved in an illusion.

This might be connected to the fact that we tend to think of color as an intrinsic property and sound as extrinsic. But, I am not sure.

9:39 AM  

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