The title of Firestone & Scholl's (F&S's) article, “Cognition does not affect perception: Evaluating the evidence for ‘top-down’ effects,” suggests an article that investigates the effect of cognition on perception. The first sentence of the abstract (“What determines what we see?”) reveals that the article is instead much more focused and discusses the effect of cognition on only a single modality: vision. Vision is of course the most important and interesting of the human modalities, and it is understandable that many researchers have specialized in its study. However, drawing conclusions about perception in general based on a single modality can be problematic. I will here illustrate this issue by discussing F&S's “Pitfall 2: Perception vs. Judgment,” F&S call the distinction between perception and judgment “clear,” (sect. 4.2, para. 1) “intuitive,” and “uncontroversial (sect. 4.2.3).” Their evidence that the distinction is uncontroversial: Perception and judgment can be in clear conflict in visual illusions.
However, the intuition that there is a clear and uncontroversial distinction between perception and judgment does not generalize well to other modalities. Take, for example, the question whether we perceive or judge that a shoe is uncomfortable. The authors' proposal is that we can judge, but not perceive, whether a shoe is comfortable or not. That is intuitively true when perceiving means seeing. We can look at the shoe and perceive that it is smaller and of a different shape than we remember our own foot to be. From that, we can judge that the shoe is uncomfortable. That is a judgment and not a perception because, in addition to the perception of the size of the shoe (and the memory of the perceived size of our foot), we also need to perform a mental comparison of the two sizes to arrive at the conclusion that the shoe is uncomfortable. When we broaden the meaning of perceiving to include all sensory modalities, it is much less obvious whether the uncomfortableness of the shoe is judged or perceived. If wearing the shoe hurts, do we perceive that it is an uncomfortable shoe, or should that also be considered a judgment because it involves an extra step from perceiving the pain to judging the shoe to be uncomfortable? If the left shoe hurts more than the right shoe, do we perceive the difference, or is anything that involves a comparison a judgment? The answers to such questions are not clear and intuitive.
The example of the uncomfortable shoe shows that outside of vision, the distinction between perception and judgment is not uncontroversial. The prime example of a modality in which it is impossible to disentangle the two is olfaction. Plato wrote that odors “have no name and they have not many, or definite and simple kinds; but they are distinguished only as painful and pleasant” (Timaeus 67a). More recently, multidimensional scaling techniques confirmed that valence is the most important perceptual dimension in olfaction (Haddad et al. Reference Haddad, Khan, Takahashi, Mori, Harel and Sobel2008). In humans, olfaction has evolved to be an evaluative sense. Olfactory information is used mainly to make decisions about rejecting or accepting food, mates, or locations (Stevenson Reference Stevenson2009). Put differently, more “than any other sensory modality, olfaction is like emotion in attributing positive (appetitive) or negative (aversive) valence to the environment” (Soudry et al. Reference Soudry, Lemogne, Malinvaud, Consoli and Bonfils2011, p. 21). Olfaction is a judgmental sense in which perceiving and judging are intertwined.
In summary, contrary to what F&S write, authors talking about “perceptual judgment” (sect. 4.2.3, para. 2) do not invite confusion about a foundational distinction between perception and judgment. Instead, they present evidence that there is no foundational distinction between perception and judgment. Consequently, the failure to disentangle perception from judgment is not a pitfall of flawed studies, but rather an acknowledgment that there is no clear division between the two. Although such a claim may seem revolutionary for vision, it is not a new idea for other modalities. We should not make the mistake of basing our understanding of perception exclusively on vision.
The title of Firestone & Scholl's (F&S's) article, “Cognition does not affect perception: Evaluating the evidence for ‘top-down’ effects,” suggests an article that investigates the effect of cognition on perception. The first sentence of the abstract (“What determines what we see?”) reveals that the article is instead much more focused and discusses the effect of cognition on only a single modality: vision. Vision is of course the most important and interesting of the human modalities, and it is understandable that many researchers have specialized in its study. However, drawing conclusions about perception in general based on a single modality can be problematic. I will here illustrate this issue by discussing F&S's “Pitfall 2: Perception vs. Judgment,” F&S call the distinction between perception and judgment “clear,” (sect. 4.2, para. 1) “intuitive,” and “uncontroversial (sect. 4.2.3).” Their evidence that the distinction is uncontroversial: Perception and judgment can be in clear conflict in visual illusions.
However, the intuition that there is a clear and uncontroversial distinction between perception and judgment does not generalize well to other modalities. Take, for example, the question whether we perceive or judge that a shoe is uncomfortable. The authors' proposal is that we can judge, but not perceive, whether a shoe is comfortable or not. That is intuitively true when perceiving means seeing. We can look at the shoe and perceive that it is smaller and of a different shape than we remember our own foot to be. From that, we can judge that the shoe is uncomfortable. That is a judgment and not a perception because, in addition to the perception of the size of the shoe (and the memory of the perceived size of our foot), we also need to perform a mental comparison of the two sizes to arrive at the conclusion that the shoe is uncomfortable. When we broaden the meaning of perceiving to include all sensory modalities, it is much less obvious whether the uncomfortableness of the shoe is judged or perceived. If wearing the shoe hurts, do we perceive that it is an uncomfortable shoe, or should that also be considered a judgment because it involves an extra step from perceiving the pain to judging the shoe to be uncomfortable? If the left shoe hurts more than the right shoe, do we perceive the difference, or is anything that involves a comparison a judgment? The answers to such questions are not clear and intuitive.
The example of the uncomfortable shoe shows that outside of vision, the distinction between perception and judgment is not uncontroversial. The prime example of a modality in which it is impossible to disentangle the two is olfaction. Plato wrote that odors “have no name and they have not many, or definite and simple kinds; but they are distinguished only as painful and pleasant” (Timaeus 67a). More recently, multidimensional scaling techniques confirmed that valence is the most important perceptual dimension in olfaction (Haddad et al. Reference Haddad, Khan, Takahashi, Mori, Harel and Sobel2008). In humans, olfaction has evolved to be an evaluative sense. Olfactory information is used mainly to make decisions about rejecting or accepting food, mates, or locations (Stevenson Reference Stevenson2009). Put differently, more “than any other sensory modality, olfaction is like emotion in attributing positive (appetitive) or negative (aversive) valence to the environment” (Soudry et al. Reference Soudry, Lemogne, Malinvaud, Consoli and Bonfils2011, p. 21). Olfaction is a judgmental sense in which perceiving and judging are intertwined.
In summary, contrary to what F&S write, authors talking about “perceptual judgment” (sect. 4.2.3, para. 2) do not invite confusion about a foundational distinction between perception and judgment. Instead, they present evidence that there is no foundational distinction between perception and judgment. Consequently, the failure to disentangle perception from judgment is not a pitfall of flawed studies, but rather an acknowledgment that there is no clear division between the two. Although such a claim may seem revolutionary for vision, it is not a new idea for other modalities. We should not make the mistake of basing our understanding of perception exclusively on vision.