[From Bruce Abbott (2016.09.27.2205 EDT)]
Rick Marken (2016.09.27.1620) –
Bruce Abbott (2016.09.27.1810 EDT)–
RM: …You are trying to argue that the taste of lemonade is a perception that corresponds to an entity in external physical reality. Powers (B:CP, 2nd Ed, p. 112) uses it to show the opposite. In PCT, the taste of lemonade is a perceptual variable constructed as a vector combination of “…intensity signals generated by sugar and acid (together with some oil smells)”. Powers goes on: “However unitary and real this vector [perception] seems, there is no physical entity corresponding to it”.
BA: An intensity signal generated by sugar would not be perceived as sweet, nor by acid, sour, nor by some oils, a particular set of smells.
These consciously perceived qualities depend on those signals activating neurons in the relevant sensory cortices.
RM: I know. Neither I (nor Bill in the quoted passage) said anything about how these signals would be perceived consciously. All Bill is saying is that the taste of lemonade is (in theory) constructed from a set of intensity signals whose sources are sugar, acid and some oils.
BA: Hmmm. Then presumably the taste of lemonade is represented by the output of a perceptual function that takes intensity signals as inputs and outputs a scalar neural signal. How does this single neural current activate the several different cortical sensory areas that produce the conscious perceptions of taste, smell, etc., and how do the activities in these different cortical areas (and/or their conscious perceptions) give rise to the experience we readily identify as the taste of lemonade?
BA: Beyond that, I think you misunderstand what Martin is saying, and base your criticism on that misunderstanding. Martin is not saying that there is a single entity “out there� in external physical reality that corresponds to the taste of lemonade. He is saying that there is a particular combination of factors “out there� that together stimulate a particular suite of sensory receptors in the right ranges of intensities to produce what we recognize as the taste of lemonade.
RM: Great. So he’s actually a constructivist since the “particular suite” of factors (I assume you are referring to environmental variables or their sensory consequences) that makes up the perception must be defined by the nervous system of the person perceiving that particular suite as “the taste of lemonade”.
BA:Â Yes.
BA: Thus, whether I experience this combination of sensory experiences or you do, we both recognize and label this experience as “the taste of lemonade.�
RM: But that’s only if your nervous system and mine construct that perception in the same way. Or is he saying that it is the “particular suite” of environmental variables (factors) itself that determines that it will be perceived as the taste of lemonade. If it’s the latter (which it seems to be) then Martin is a Gibsonian rather than a constructivist. A constructivist is just a Gibsonian who has learned how to model perceptual systems (like my PhD adviser).
BA:  When you first experienced lemonade, you learned what it tastes like (to you) and what to call that taste (“lemonade�). That taste is experienced when certain constituents are present in the drink. Whether you experience the same taste as I do when drinking it is something we do not and cannot know.  What we can know is that when those constituents are present, we agree that the taste is that of lemonade. I would go further to suggest that my nervous system and yours probably construct that perception in the same or very similar ways, but that is a conjecture, although one that is open to empirical test. I suspect that our systems are far more similar than one might expect if perceptual functions like those involved in the taste of lemonade were constructed through random reorganization.
BA: Furthermore, we could use the test for the controlled variable to determine what needs to be present physically in a glass of water for its taste to be perceived by the drinker as that of lemonade.
RM: I think you might still have trouble because if his view is Gibsonian – if he actually believes that a “particular suite” of factors determines the perception – then he might have trouble accounting for the fact that a different suite of factors tastes like lemonade to different people. This could result from a difference in perceptual functions or, more likely, in differences in the reference for the perception (I might like my suite sweeter than you like yours, for example).
BA: I allowed previously for the likelihood that there is a range of combinations within which one would still call the taste that of lemonade, although perhaps one might add some modifiers such as sweet or tart. I doubt that the lemonade would taste sweeter to you simply because you have a different reference for the perception. The lemonade would taste the same but on tasting it you might complain that it isn’t sweet enough for you.
BA: (Anything that will stimulate the right sensory receptors, in the right proportions of intensities, will do so, even if chemically it does not correspond to what we normally label as lemonade.)
RM: Yes, it sounds like Martin is just an inch away from the PCT view. All he has to realize is that it’s the perceptual function that determines the “right” sensory receptors to stimulate and how much they should be stimulated. The perceptual function constructs the perception (the taste of lemonade) from the “particular suite” of sensory stimulation.
BA: Your statement above reminds me of a “Peanuts� cartoon. Lucy points to something on the ground and explains to Linus that it’s a rare butterfly from Brazil. Linus looks closely at the object and declares, “It’s not a butterfly, it’s a leaf!� Lucy replies, “Gee, I wonder how it got here from Brazil?�
BA: And after all the years you have known Martin, seen his PCT diagrams, and read his writings on PCT, you don’t think he understands how, according to PCT, perceptual input functions work? That he is still “an inch away� from the PCT view? Why not just admit that your initial assessment of Martin’s position was wrong?
Bruce