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Sensation & perceptions are used interchangeably in common culture so I'm confused on their exact meanings.

From: Rand, Ayn; Binswanger, Harry (1990-04-26). Introduction to Objectivist Epistemology: Expanded Second Edition (p. 5). Penguin Group. Kindle Edition.

Sensations, as such, are not retained in man’s memory, nor is man able to experience a pure isolated sensation.

From: http://www.alleydog.com/101notes/s&p.html#ixzz26F1dd027

1) Sensation occurs:

a) sensory organs absorb energy from a physical stimulus in the environment.

b) sensory receptors convert this energy into neural impulses and send them to the brain.

2) Perception follows:

a) the brain organizes the information and translates it into something meaningful.

The Rand reference states that man cannot experience a sensation by itself. The link reference states that a sensation is something that is physically translated into the brain. The brain then organizes and translates it into something else (a perception).

If I am poked by a pin, am I aware of a sensation or a perception? If I use the article's definition, there's a possible interpretation that my brain translates my sensations into a perception prior to that signal hitting my consciousness.

asked Sep 12 '12 at 04:21

Humbug's gravatar image


edited Sep 12 '12 at 17:08

On point 2)a) - A percept is a group of sensations automatically retained and integrated by the brain of a living organism.

Meaning is maintaining the connection between the word(s), concept(s) and the referents from which it was abstracted.

(Sep 12 '12 at 18:38) dream_weaver ♦ dream_weaver's gravatar image

This is something I also found confusing when studying Rand's theory of epistemology, but I believe a perception "is something" when it is perceived, whereas a sensation has no clear identity or meaning - it is the reception of the impulse at a physical level before the mind steps in. When you look at a table it is not a blob indistinguishable from the chair next to it. You recognize both and would recognize them as the same objects if you turned away for a time and then turned back to look at them again. It's hard to separate when we think of objects perceived through our vision since as humans we automatically organize objects we see into percepts. Imagine being blindfolded however and walking through a room, bumping into one object after another, these would be closer to mere sensations. Or imagine hearing a bunch of noise that you could not recognize or organize into something meaningful or identifiable, as opposed to hearing the sound of a familiar voice that you would recognize every time you heard it.

These are not perfect examples, because as soon as the sensation hits the brain it is already on its way to becoming a percept, so one could argue that the mere noise is still distinguishable from a different set of random sounds - but I think they help demonstrate the difference.

The other thing that seems helpful here is to use an animal's context, such as a pet dog. My dog clearly knows my voice and clearly recognizes his leash or my shoes and the jingling of my car keys. Whenever he perceives these things he immediately gets excited knowing a walk or car ride is imminent.

But when we drive in the car and he has his head out the window, he is likely not perceiving objects, he is absorbing a myriad of sensations of objects and smells, at least initially.

The example of the pin poke again could be used to simulate a mere sensation, but again, the brain does process this and we can identify a pin poke as a pin poke and not the poke of a finger, for example.

I think this is why Rand says we cannot experience a wholly isolated sensation, but we can still understand the difference between the physical aspect of what our senses absorb compared to the change that takes place because our mind does something with that impulse.

answered Sep 13 '12 at 12:43

la_phil's gravatar image

la_phil ♦

Some examples might help, here.

Tingling in your fingers is a sensation. This kind of sensation can happen if the circulation in your arm as been cut off for a while. A sensation, as such, is a way your body, or a part of your body, might feel, independent of any identification of the cause of that feeling.

Nausea is also a sensation. Dizziness is a sensation. Pressure is a sensation. Pain is a sensation. Hot and cold are sensations too. So is sound, and smell, and light, and also taste. Each sense, as such, works by means of sensations.

Note that sensation as such is not essentially concerned with any external object causing the sensation. Sensation is a form of experience. For instance, when you press on the side of your eyeball, you get a sensation of light.

Perception, however, is the experience of objects of consciousness qua objects. On perceives a person, or a cat, or a car, by seeing, hearing, smelling, and/or touching it. Sensations are the means to perception, but external objects are the objects of perception.

The more modes of sensation are employed, the richer a perception is. One can perceive (and even identify) a dog just by hearing it bark, but if you see it, smell it, and touch it, you have a richer perception, from which you can make more specific identifications. "This is a dirty, wet, friendly, brown, Labrador retriever."

Perception precedes conceptual identification. When you see a cat, you perceive it before you know it is a cat. Of course, some things perceived are easier or harder to identify. I often see things which I cannot identify until I get close enough to them.

It's possible to focus on one's sensations, but it requires a special act of consciousness to separate them from one's perceptions. For example, I perceive the chair I'm sitting on, but I have to focus on the pressure of it on my buttocks and thighs. We don't normally think about our sensations; we think about the things we perceive.

answered Sep 15 '12 at 11:01

John%20Paquette's gravatar image

John Paquette ♦

I know that I can consciously block identification by focusing on something else. Objectivism holds that perception is automatic from sensation. So if I'm blocking identification, am I not perceiving it? e.g., I am not always aware that I'm sitting on a chair.

(Sep 16 '12 at 13:08) Humbug Humbug's gravatar image

Identification is after perception. Perception is the basis of identification. If you don't perceive something, you cannot identify it.

You can, of course, choose where to look, and so you can choose not to perceive anything "over there". I'm not sure how you can fail to perceive a chair you are sitting on, unless your butt is numb.

You can perceive whatever you are sitting on, without identifying it as a chair or bench or table or anything else. Perception doesn't require identification -- it's the other way around.

(Sep 16 '12 at 14:52) John Paquette ♦ John%20Paquette's gravatar image

Let say something is touching me that I am unable to identify because the room is dark and I've never experienced this object before. Am I perceiving it or am I sensing it? If it's touching me and I can sense both pressure, texture, and temperature, am I perceiving 3 different sensations?

I guess I'm struggling to draw the boundary between sensation & perception.

(Sep 17 '12 at 01:12) Humbug Humbug's gravatar image

A feeling of pressure against your butt is a sensation. As soon as you start thinking, though in terms of some cause of that feeling which is outside your body, as in "something is touching me", that's perception.

A sensation as such is disembodied. Perception is of some body. That's why its virtually impossible to have just a sensation, because most sensations are caused by something we perceive, which means you are perceiving.

Sensation is not essentially of an object. Sensation just is. Perception is of an object.

(Sep 17 '12 at 09:49) John Paquette ♦ John%20Paquette's gravatar image
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Asked: Sep 12 '12 at 04:21

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Last updated: Sep 17 '12 at 09:51