Practical Science on Movement and Pain

Book Excerpt: Sensation Versus Perception

Since I’m in the process of writing a book, I don’t have much time to post. So here’s a little excerpt from the book. It’s about the distinction between sensation and perception.

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Although the terms sensation and perception are often used interchangeably in everyday life, psychologists distinguish between them. The distinction is very useful in understanding movement.

Sensation refers to the detection of some stimulus in the periphery and the transmission of a sensory signal towards the central nervous system. Perception is the process of taking that sensory information, filtering it, organizing it, and interpreting its meaning to create a subjective or conscious experience related to the sensation.

For example, through sensation the ears report information about sound waves to the brain, and through perception we hear music. In the context of movement, sensation reports proprioceptive information, and perception creates kinesthesia, or a felt sense of the movement. (By the way, the term “proprioception” sometimes causes confusion, because it is sometimes used to refer to a sensation, and others times a perception.)

It is useful to distinguish between the two because they are not identical. Many factors can modulate perception, including the way we focus our attention, our past experience, and our expectations. Thus, two people can receive the same sensory information, but perceive completely different things.

408154aa.2Look at the picture to the right. You can “see” it in two different ways – as one vase, or two faces looking at each other. The sensory data flowing to the eyes remains the same, but the perception of the picture completely changes as the brain alternates back and forth between competing interpretations of the meaning of sensory data. Notice that you can’t “see” both pictures at the same time!

As stated by prominent neuroscience researcher Paul Bach-Y-Rita: “We see with our brains, not with our eyes.”

The illusion reveals that there is a great degree of nearly instantaneous calculation and interpretation happening beneath our awareness, before we see anything. Our experience of vision is not a pure unmediated reflection of the real world – it is our brain’s construction of a picture that it thinks, based on available data, is a useful representation of what we need to know about the world.

Similarly, our kinesthetic sense of the body is not just a mirror of body position, but a construction that is created to serve functional goals. Just as you can see the same picture different ways, you can perceive the same movement in different ways, depending on how you interpret the sense data created by the movement.

Imagine performing a complex movement that you have never done before, such as a backflip, a new dance move, or a golf swing. Your perceptions about the relative positions of your joints during the movement will likely be confused and inaccurate. In other words, you literally won’t know what you are doing, and you won’t be able to predict the consequences of your movements.

This is not because of some defect in sensation, or the quality of proprioceptive information flowing to the brain. The problem is in perception – the brain’s ability to interpret the meaning of that information. In the case of a novel movement, the brain has no past experience organizing similar information, and therefore it does a poor job.

With practice, the brain gets feedback about the correspondence between a particular perception and actual reality. For example, if you perceive that your feet are in good position to land a flip, you will quickly realize your mistake when you land on your butt. As you get more feedback, perception about body position will improve, and eventually you will know where everything is and what it is doing during the movement.

Therefore, the difference between an elite athlete and an everyday Joe in terms of body sense is probably more about perception than sensation. Each are likely receiving similar sensory information about movement, but the athlete has far more skill in accurately and quickly interpreting the meaning of that information and creating functionally useful perceptions.

The distinction between sensation and perception is analogous to the distinction between nociception and pain. Nociception is just sensory information from the body, which does not result in a conscious perception until it is processed and interpreted. Further, like other perceptions, pain does not exist just to reflect the objective condition of the body, but to serve a functional purpose – protection against perceived threat.

In the next section we will look at the body maps, which will give us insight into how perceptions about the body are formed in the brain and how we can change them to move better and feel better – even without changing the underlying sensations.

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End of excerpt. What do you think?

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16 Responses to Book Excerpt: Sensation Versus Perception

  1. Brent says:

    Great stuff Todd. When is the book coming out? ebook? Speaking as a personal trainer and someone who is a fan of Gray Cook’s work, there was a ton of info. in not only Gray’s book and blog, but in the hands-on part of the fMS seminar, speaking to how important mobility and proprioception is. This is in large part why I’m not a huge fan of high intensity exercise modalities like Crossfit, p90x, insanity, and my favorite ‘the biggest loser,’ not because they are inherently dangerous ways to train, but because most people simply aren’t prepared for them (and it clearly shows). I strongly believe we need to slow down (both mentally and physically) first and foremost to allow our brain to filter and organize our movements. This is what is sorely missing in the fitness profession in my opinion where too many put a premium on burning calories first and foremost, not realizing that creating a more efficient and organized CNS will make people not only more efficient, but reduce the likelihood of getting a ridiculous amount of ouchies <–scientific term of the day

    Brent

    • Jeremy says:

      Brent, I agree with what you are saying. I also follow Grey Cook’s work and use the SFMA as part of my evaluation on every patient in practice. He breaks down dysfunction movement patterns into mobility or stability/motor control issues.
      Todd, with what you are saying, this makes perfect sense in understanding stability/motor control dysfunctional issues. With CrossFit, I think the philosphy and principals are sound but the issue lies that most of the CrossFit boxs are trying to make money so they are getting people in there that have no business being there or the owners have no idea how to program or properly progress individuals through. They should all have someone who is trained perform the Functional Movement Screen come in and evaluate new members. That way there is some accountability.

      • Brent says:

        I have to disagree in regards to philosophy and principle. Their philosophy is based on running people into the ground (even though they are clever at not marketing it as such). Furthermore, most don’t have a clue how to design a training program (i.e. doing olympic lifts and plyos for volume…in a circuit fashion is a terrible idea). They are great at building a community, but unfortunately most ‘boxes’ don’t know what they are doing.

  2. Steve says:

    Great “appetizer” for what is to come in your new book. Can’t wait to read the rest…Excellent!

  3. This is a very good description and explanation. Useful for anyone needing to understand movement coordination, actually for coordination of anything with the body and mind.
    Thanks a lot, Tod,
    Adri

  4. Mark Hollis says:

    Todd, always appreciate the clarity and conciseness of your writing. Can I/we pre-order the ebook?

    Many thanks

    • Todd Hargrove says:

      Hi Mark,

      Thanks for the compliments and the interest in the book. I will look into preorders, I haven’t thought much about it. There will be an e-book and hard copy. I should hopefully be done by end of the year.

  5. Todd, I am reminded of Morris’ contention that pain itself was “downgraded from a perception to a sensation” about 1870. This, predictably, led to an epidemic of chronic pain.

  6. Very useful distinctions even for me to really clarify in my thinking and communicate.

    Great, simple to understand writing as always. I have one area that caught me for a moment.

    Quote:This is not because of some defect in sensation, or the quality of proprioceptive information flowing to the brain. The problem is in perception – the brain’s ability to interpret the meaning of that information. In the case of a novel movement, the brain has no past experience organizing similar information, and therefore it does a poor job.

    End quote.

    This isn’t a problem of perception either. “Having no past experience organizing a similar job” the brain is busy accumulating sensations including environmental responses and as it gets more “data” the response improves. You go on to say this beautifully and using the word problem may be the easiest way to say it. But it catches my eye since the learning process is seen as a problem by so many adults.

    Maybe something like, “the originator of this confusion is perception not sensation” could be useful.

    Sorry if the above is more than you were looking for. Once you process your sensation to the reading of my comments and provide a response based on your perception, I will do the same. Hopefully my perceptual capacity will grow and allow me to make even more appropriate comments in the future.

  7. Hi Todd-

    This is really great work and I appreciate the time you are taking to educate people. I wonder if you are going to speak about external vs internal feedback mechanisms and how the elite athletes reach their potential with guided external feedback as an important part of that process vs. how learners without a coach rely more on internal feedback mechanisms.

    Thanks and good luck with the rest of the book!

    • Todd Hargrove says:

      Hi Carolyn,

      Thanks for the kind words. I think my book will probably touch on external versus internal cueuing at least a little bit. Definitely an interesting subject!

  8. Rohan says:

    Great material and writing as usual.

    I’m interested in where your background in Rolfing fits in and how it might feature in the book – it’s always nagged at me a bit that Rolfing seems to be about better alignment = reduced pain (based on no direct experience and a shallow reading of the modern practice – I.e. My local Rolfer’s website talks at length and exclusively about alignment…) – wheras we know that this causal relationship is shakey at best (based on studies that look at teenagers with “good” vs “bad” posture and subsequent incidence of back issues).

    Also keen to get your take on the Prague school and DNS – hard to get the low down on the evidence base for their stuff given the language difference.

    Cheers

  9. Vaiva says:

    Hello,

    thanks for a great article.

    I have a question. A good sensation is a gift or a skill?

  10. Todd, I think this topic is ultra important not only for trainers but for athletes and clients to understand & digest. As someone who geeks out about such topics I have to say, this reads kind of dry. :-[ I suggest adding bolded or highlighted sentences for those who skim & scan, and perhaps pare down the language to make the meat more concise. It also couldn’t hurt to interject a little humor or personality….unless of course you don’t have those things. ;-) Keep at it!

    • Todd Hargrove says:

      Thanks for the feedback Michele, point taken. This is actually one of the “drier” parts of the book. But dry to a “geek”? I do not think that word means what you think it means.:)

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