Is Pain a Sensation or a Perception?
An attempt to dissolve an unproductive debate
For several years, there has been an intermittent debate happening on social media about whether pain is a “sensation” or a “perception.” Here are the different sides as I see them:
A very small number of people have argued that pain is a sensation and not a perception.
A much large number have responded that this is basically the reverse of how these terms are defined in the relevant literature.
An even larger group has watched the debate from afar and wondered whether it has any substance or practical implications.
This post is written mostly for the third group and argues that:
The debate is not substantive or of practical import. It does not involve disagreements about pain physiology, what causes pain, or how pain should be treated. Instead, the debate is semantic.
The debate is easily resolved by simply looking at textbooks that describe how the terms sensation and perception are conventionally defined and used.
These textbooks make clear that it is completely appropriate to refer to pain as a perception, and it doesn't make much sense to say that pain is a sensation but not a perception.
In any event, it doesn’t matter that much how we use these words in practice, because they are inherently fuzzy and often used interchangeably.
Read on if you’d like a review of the extensive evidence supporting these points. Did you know that there are at least eight textbooks literally called Sensation and Perception? I have included some relevant quotes from at least three below.
Definitions of sensation and perception
Below is a quote from an online course in Intro Psych with a page titled “Sensation and Perception. The page provides a broad overview of the physiological processes governing sight, hearing, smell, taste, proprioception, touch and …. pain. Here’s how it defines the major terms:
Sensation occurs when sensory receptors detect sensory stimuli. Perception involves the organization, interpretation, and conscious experience of those sensations.
Here’s a near identical definition from another online textbook:
Sensation is defined as the process of detecting a stimulus and converting it to neural activity. Perception is how that sensory information is filtered, organized and interpreted, based on past experience, to create a conscious experience about the stimulus.
And here’s a similar but slightly more detailed distinction from a 2017 textbook called Sensation and Perception by Schwartz and Krantz:
Sensation refers to the registering of a physical stimulus on our sensory receptors. That is, sensation is the earliest stage of a process that starts off in the eyes, ears, or skin and ends in the higher centers of the brain. Sensation changes physical stimuli, such as light, sound waves, and mechanical vibrations, into information in our nervous systems. Perception, by contrast, refers to the later aspects of the perceptual process. To be specific, perception involves turning the sensory input into meaningful conscious experience.1
The Schwartz textbook has a chapter on pain, where it states that:
Pain is the perception and the unpleasant experience of actual or threatened tissue damage. … nociception is the activation of sensory receptors.2
I think these quotes make it perfectly clear that:
it is appropriate to refer to pain as a perception
it is appropriate to refer to nociception as a sensation
it doesn’t make sense to claim that pain is a sensation but not a perception
This is why experts on pain such as Tasha Stanton, Lorimer Moseley and Mick Thacker use this terminology when explaining why nociception does not necessarily result in pain.
Despite these points, as described below, I think it’s fine in some contexts to refer to pain as a sensation, as in the phrase “pain is an unpleasant sensation." This is because the terms sensation and perception have a long history of evolving usage, are inherently fuzzy, and are often used interchangeably.
The definitions are fuzzy and don’t matter that much
Each of the textbooks I reviewed makes clear that the terms sensation and perception are inherently nebulous and there's no bright line between them.
Why not? Because they encompass a vast number of different physiological processes happening at every level of the nervous system, and governing all our conscious experiences about the world, including sights, sounds, tastes, smells, touches and pain. Thus, they cannot identify such events with any specificity or precision.
Instead, they are used to illustrate a basic fact about the neural hierarchies that govern our conscious experiences: on the “bottom” end near the sensory receptors, information processing is relatively simple, reflexive, and unimodal. On the “top” end near the brain, information processing becomes more complex, integrated and multimodal. This distinction helps us understand the nervous system, but it doesn't lend itself to using the terms sensation and perception in a specific manner.
This point is explained in another textbook called Sensation and Perception by Goldstein and Block.3 The introduction notes the distinction between sensation and perception, but then immediately clarifies that: there is no bright line between them; the words have a long history of use that has evolved over time; and the current trend is to use the word perception more and sensation less, because research is showing more and more that filtering and organizing of sensory data begins almost immediately after transduction:
This book takes the position that calling some processes sensation and others perception doesn’t add anything to our understanding of how our sensory experiences are created, so the term perception is used almost exclusively throughout the book …
Sensation was discussed in the early history of perceptual psychology … [but] researchers eventually stopped using the term sensation … so sensations are historically important … but as far as we are concerned, everything that involves understanding how we experience the world through our senses comes under the heading of perception.4
A similar point is made in (yet another!) book called Sensation and Perception by Foley and Matlin:
Psychologists acknowledge a fuzzy boundary between these two terms, although we could reasonably shorten the title to Perception.5
Goldstein and Block also acknowledge that there are different conventions about the usage of sensation and perception, and that there isn’t any right or wrong about this usage in many cases.6
This explains why scientific authorities will often use the term sensation quite broadly, even when referring to conscious experience. For example, you can find studies where pain is referred to as “an unpleasant sensation.” Of course you can also find papers talking about “the perception of pain.” Either usage is fine, because in each case, readers will know what the phrases mean.
But I don't think you will ever find the following statement in the scientific literature: “pain is sensation but not a perception.” Because this statement is confusing, and doesn’t make sense given what we know about the history of these terms.
So I think it’s best to avoid making that statement.
What about how we talk to clients?
I think this is the primary concern of the people saying we should not call pain a perception. Each have argued that it might be stigmatizing to tell a client that their pain is a perception. This might imply that the client is to blame for their pain, or that the pain is happening because of their psychological weaknesses, or that the pain is not related to tissue damage or nociception.
It seems possible that certain clients might be harmed by hearing that their pain is a perception. For others, this thought might be empowering. Either way, this is a completely separate issue from the question about how pain should be described scientifically.
I think everyone on both sides of the debate should agree that how you talk with a client about pain might need to be different from the way you talk about pain with colleagues, or in a scientific paper.
For the latter purposes, I hope the above material is helpful.
Here are some related articles that might be interesting:
References
Schwartz and Krantz 2017. Sensation and Perception, 2nd Edition. Excerpts available at https://www.google.com/books/edition/Sensation_and_Perception/usBADwAAQBAJ?hl=en&gbpv=1&dq=sensation+and+perception&printsec=frontcover
Schwartz and Krantz at p. 409
Goldstein and Block 2010. Sensation and Perception, 10th edition. Excerpts available at https://www.google.com/books/edition/Sensation_and_Perception/x5d4CgAAQBAJ?hl=en&gbpv=1&dq=sensation+and+perception&printsec=frontcover
Goldstein and Block at p.6
Foley and Martin 2016. Sensation and Perception, 5th Edition at p. 2. Excerpts available at https://www.google.com/books/edition/Sensation_and_Perception/jLBmCgAAQBAJ?hl=en&gbpv=1&dq=sensation+and+perception&printsec=frontcover
Goldstein and Block at p.6