A blog about problems in the field of psychology and attempts to fix them.

Saturday, April 21, 2012

Two Ecological Approaches 30 years later

Abstract:  In 1982, Cutting pointed out that two distinct theoretical programs were developing within the tradition rooted in James J. Gibson’s work on perception: Ecological Psychology. Thirty years later, the two traditions are alive and well. While the distinctions between them are still rarely discussed in print, they have become even more obvious, as the traditions have continued to develop in the directions predicted in Cutting’s paper. Updating the status of the “two ecological perspectives” requires both an assessment of the research generated by the two different perspectives, the theoretical arguments in which the differences are most salient, and the reasons why no rift has formed in the field. Part of the reason ecological psychology has stayed unified seems to be the focus on, and respect for empirical progress. Another important factor seems to be ecological psychologists’ diversification into research areas more concerned with methodological sophistication than with theoretical baggage.

---------------Below are excerpts from a paper I am preparing. The paper is mostly finished. This is a summary, and I would greatly appreciate any suggestions. In particular, I am looking for papers or books that continue to evidence these issues as important to the field - Chemero's book and Andrew and Ken's online debates are clear examples, as well as the explicit debates about afforadnces in Ecological Psychology. However the issues are deeper than that. Any suggestions and comments welcome. ---------------

Two Ecological Approaches 30 years later
(Excerpts from a draft)

Most controversy between ecological psychologists and those outside the ecological tradition revolve around descriptors of the above phenomenon, particularly the notion of “direct perception.” These controversies have often been highly public (e.g. the in-press debates variously including Gibson, Mace, Reed, Shaw, & Turvey on the one hand, Fordor, Gyr, and Pylyshyn on the other). Less public have been the controversies within the ecological psychology community, with the notable exception of James Cutting’s 1982 article “Two Ecological Perspectives: Gibson vs. Shaw and Turvey.”

Robert E. Shaw and Michael T. Turvey were knights triumphant in the first wave of Gibson supporters, crucial in the advancement of the discipline, and extremely influential on the current generation of ecological psychologists. Commenting on the eight-year-old collaboration between Shaw and Turvey, Cutting claims to have “hard evidence that Shaw and Turvey are not systematic followers of Gibson. They are revisionists who present a new ecological perspective.” (p. 200) The differences between Gibson’s perspective and Shaw and Turvey’s perspective were newly emerging at the time that Cutting wrote his article, but his insights were keen. Indeed, the differences are even more extreme and obvious now. Nevertheless, ecological psychology remains a stable, and fairly unified approach. The main implication of Cutting’s analysis, that a paradigmatic split of some sort was coming, seems not to have materialized. After thirty years, it is worth reassessing the two ecological perspectives.

Cutting’s Two Perspectives

Cutting labeled the first approach as that of Gibson, and as the ecological “formulation.” I keep the initial label. The second approach was labeled as the Shaw and Turvey perspective, and as the ecological “reformulation.” Due to their role in founding and leading the University of Connecticut’s Center for the Ecological Study of Perception and Action, it would now be easier to label their perspective the Connecticut approach. This term has the added benefit of being the term used in casual conversation amongst ecological psychologists.

Cutting lists several similarities and distinctions between the Gibson’s perspective and the Connecticut approach. Not all are relevant in comparing the two approaches today, and new distinctions have emerged. The similarities, discussed briefly, include use of metaphor, domain specificity of terminology, and penchant for formalisms. The criticisms, discussed at length, include:

Distinction 1: Necessity of Direct Perception
While Gibson’s perspective argues for direct perception being the normal, or at least natural, state of perception, it allows for indirect perception. In contrast, the Connecticut approach declares all perception to be direct (Cutting, 1982, p. 204). This is not just a definitional problem, but a methodological assertion – the Connecticut approach seems to hold that all situations that seem to involve indirect perception will be revealed to involve direct perception following further analysis.

Distinction 2: Possibility of Perceptual Error

Similarly, for Gibson perceptual error is rare. In contrast, the Connecticut approach declares perceptual errors non-existant (Cutting, 1982, p. 210). This might be an issue of definition, but if so it is unclear whether the definition in question is that of “perception” or that of “error.” It is also unclear what place this leaves in the Connecticut approach for perceptual learning. Perceptual learning is normally presented as a process of becoming better attuned to invariants, which seems to necessitate some degree of initial.

Distinction 3: Multiplication of Terms
Gibson was extremely careful with language, and though he did add terms unique to his system, they were rare. In contrast, the Connecticut approach introduced several new terms, quite rapidly (Cutting, 1982, p. 207-208). While this is not obviously problematic, in and of itself, Cutting’s additional assertion that the novel terms jeopardize the internal consistency of the system is worth further discussion.

Distinction 4: Effectivities
In example of the last point: For Gibson, affordances pointed both ways, but the Connecticut approach adds the term ‘effectivity’, which creates a duality of the type that Gibson seemed to eschew (Cutting, 1982, p.211-213). While Cutting brings up several additional terms of the reformulation that seem to have this flaw, they are no longer common in ecological psychology’s discourses.

Distinction 5: Term Meanings
The above points coalesce in different meaning that the two approaches give to the basic terms of the ecological approach, including “invariants”, “affordances”, and “constraints” (Cutting, 1982, p. 214-216). In each case Cutting asserts that the different meanings are incompatible, and he further claims that the meanings used by the Connecticut approach can lead to uninformative, circular definitions.

Conclusion
In conclusion Cutting notes that Turvey and Shaw proffer a position quite close to Gibson, and that the two approaches “fully deserve to be classified as kindred perspectives on psychology.” (p. 217) None the less, he believes he has done a service if has made more psychologists aware that a difference exists.

It is my belief that what the reformulation says is not always consistent with what Gibson said, and that few people currently recognize this…. It is my belief that both views of Gibson and of Shaw and Turvey should be known, and be known to be different in some important areas. (Cutting, 1982, p. 210, footnote 1)


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Thirty Years Later

[The field has diversified tremendously.] As this diversification and maturation has occurred, the presence of two distinct approaches has remained. If anything, the two approaches have continued to develop in disparate ways, leading to growing awareness of the distinction. Despite this, and even with growing discussion – in print and at conferences – about the alternative approaches, the field has not fissured, and shows no signs of doing so in the immediate future. An update on the distinctions between the perspectives, and an evaluation of the solid base of the discipline is in order.

Reassessment of the Two Perspectives

Distinction 1: Necessity of Direct Perception
Opinions about the necessity of direct perception continue to distinguish the two approaches. It is a typical first step of an ecological research program to pick a behavioral task and try to identify the perceptual support for that task, with the hope that the researcher will find a single mathematically-describable visual (auditory, haptic, etc.) variable that can guide accurate behavior. This step is used both by those following the Connecticut approach and Gibson’s approach. However, the Connecticut approach treats the identification of such variable an absolute necessity for research to continue in a sensible manner, and this is best represented in what might be called Turvey’s dictum: If you have not found the invariant, you have not looked hard enough.

... the Connecticut approach seems to intend the dictum as an ontological and metaphysical axiom: “Given any task, properly conceived, there exists an invariant that is used to support the behavior in question.” ... In contrast, Gibson’s original system both allowed the possibility that some tasks lacked specifying invariants, that is, that the tasks had imperfect perceptual support; and allowed the possibility that some tasks have specifying variables that go unused.   There are two ways to view Turvey’s dictum in relation to the more egalitarian nature Gibson’s original system.... The second possibility, which seems to be favored by the Connecticut school, is view it as axiomatic that sufficient investigation will result in all behaviors being supported by direct perceptual, and thus to view any alternative suggestion as a failure to be sufficiently orthodox.

Distinction 2: Possibility of Perceptual Error
In the converse of the above distinction, the Connecticut school’s requirement that all perception be direct seems to imply that perceptual error never occurs. This is not to say that perceptual error might not seem to occur, but to assert that all such instances can be re-conceptualized to reveal the invariant the organism is sensitive to, and thereby show us how the behavior was guided by direct perception... [But] Gibson, in contrast, regularly wrote about the possibility of perceptual error and the conditions under which it might be expected. This is especially obvious in Gibson’s discussion of restricted perception... [and] is also apparent in the discussion of perceptual learning that characterized Eleanor Gibson’s work.....

Distinction 3: Multiplication of Terms
While it is true that Gibson was very careful in crafting terms, and did so rarely, and that the advent of the Connecticut approach lead to a slew of new terms being introduced, I do not believe this distinction remains. Most of the terms concocted during the great proliferation have gone by the way side, and those that remain are used by members of both approaches. Further, there are now members of both approaches that are very conservative with their terms, and members of both approaches that are very adventurous. Thus, what began as a clear stylistic difference between the leaders of the two approaches, did not become an enduring distinction between the approaches. The only Connecticut-introduced term that remains notably problematic is “effectivities”, and that is primarily problematic because of the way it shapes the Connecticut approach’s understanding of affordances.

Distinction 4: Effectivities
A key term in both approaches is “affordance,” a noun made out of the verb “to afford.” .... Gibson’s approach to psychology defined affordances as a relational property, a higher-order property of the organism-environment system, one that required specification of the situation, the action, and the organism.... In contrast, the Connecticut approach treated affordances as a higher-order property of the object itself – as a combination of object features.... This minor difference led to the creation of a new term, a term for the organism-properties that complement the object properties - effectivities. Effectivities are higher-order properties of organisms...

Disagreements between the two approaches thus often become debates over how to use the term “affordance” and whether or not we should even have the term “effectivities.” ...

Distinction 5: Term Meanings
As discussed above, the two approaches still seem to use some key terms in distinct ways. Indeed, the debates about term usage that continue to be published every few years in Ecological Psychology might lead one to believe that there is a deep internal schism in the field, of the type Cutting predicted might develop. However, the view from within the field is quite different. These issues rarely garner explicit discussion at meetings, and while there are strongly held views, I think most researchers understand that these issues are secondary, and that the agreed upon issues are far more important. Routinely, at conferences, I have witnessed a talk that used terminology in the manner preferred by the Connecticut approaches alternating with talks that used terminology in the manner preferred by Gibson’s approach, and no one listening flinched.

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Looking Forward

The field of Ecological Psychology will continue to go forward, driven by its empirical success in tackling problems of perception and action. The two approaches will be reconciled, now that Turvey and Shaw have retired. As a new generation of energetic people develop further extensions of Gibson’s system, while also trying to return to the original tradition.



23 comments:

  1. This is interesting, and it is definitely worthwhile to revisit the Cutting paper. But I'm not sure here are still two ecological psychologies present at the meetings. It seems to me that nearly all of he participants are students ( or grand students) of Shaw and/or Turvey, and that the perspective Cutting identified as Gibson's doesn't make much of a showing. Maybe seeing your whole paper, with the references, would make more clear who the "Gibsonans" at the eco psych meetings are. I see myself as a Cutting Gibsonian, I guess, but no one there believes me. Moreover, it seems to me that it is the Connecticut crowd that has made all of the empirical progress.

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  2. Tony, I agree and I disagree.

    1) The conference is dominated by the Connecticut crowd, but I hear many of murmurs of unhappiness about that. That it is only murmurs is part of what keeps the peace.

    1b) You will see plenty of talks in which people clearly conceptualize affordances as relational and then move on. Similar with the other differences - many don't use the term 'effectivities' or 'dispositions', many talk about perceptual errors, etc. Typically none of this is questioned.

    1c) Also, there are many people who were inspired by Gibson's work who have never attended one of our meetings, or who attended and were turned off. Thus, I am not sure if "visible at the meeting" is a good criterion.

    2) You are certainly correct that the majority of empirical progress has been made by people who are professors, grad-students from, or great-grad-students from U Conn.

    I am not sure, however, if point 2 is relevant to this discussion. I think it is just neutral. It is unsurprising that the people in charge of the only dedicated research center (CESPA), which houses the only dedicated graduate program (PAC), have made the most empirical progress.

    Also, in terms of most studies, taken individually, I suspect that the only difference between the Gibson approach and the Connecticut approach is a matter of vocabulary. More important differences, I suspect, are visible only across studies: in the trajectories of labs, in the discussions that lead to study planning and follow up, in the topics chosen for investigation. Thus, it is easy to see the difference as no big deal - because the 'big deal' happens on a very large time scale.

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  3. Several things come to mind....

    1. What was Cutting's REAL motivation for writing that paper? The reason I ask is because I encountered that paper in grad school and brought it up to my advisor, Tom Stoffregen, and couldn't get him interested in discussing it with me. If memory serves (and Tom, if you're out there reading, I apologize if my memory's faulty), Tom dismissed the paper as nonsense.

    2. I once read a comment by Jackie Gibson that she never understood a lot of Shaw's approach (I'm not then ashamed to admit it, neither do I). I took that to mean that perhaps she saw some kind of difference between the "Cornell" school and the "Connecticut" school. IDK.

    3. To this day, when I read Cutting's remark, "that Shaw and Turvey are not systematic followers of Gibson. They are revisionists who present a new ecological perspective," I have a so-what moment. Gibson wasn't Freud, demanding theoretical subservience from his students.

    -Jim Jackson

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  4. Jim,
    Thanks for the comments! This is really helping me think out parts of the paper.

    I think Cutting's real motive was to a) make clear the rift he saw forming and b) to anticipate the fracturing of the field. He was a younger member of Cornell's psych department, likely had been involved in getting Gibson hired, and likely wanted to stick up for Gibson against people he saw as doing something different while invoking Gibson's name.

    In addition to my general motivation for seeing this paper revisited, because I think it was insightful, I am motivated to point out that Cutting was wrong about point b. Given that I agree with the premise of two distinct approaches, it seems worth trying to explain why there has been no rift.

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    Your comment about Tom is amusing. I have had the pleasure of interacting with Tom at the last few ICPA conferences. It does not surprise me that, having been effected strongly by this rift most of his career, Tom would still not see the use in Cutting's paper.

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    Gibson's lack of stricture has certainly contributed to the confusion. Probably, Gibson (and Turvey, Shaw, and Mace) would see a little confusion as a small price to pay for the clear advances that have been made in the field. Thus, 'so-what' is a reasonable response. There is only something more to talk about, if you think that it is important to note differences in approach, and you think people have not noted the difference.

    The point is not to accuse TSM are doing something wrong (Cutting asserts several times), but simply to make it clear that they are doing something different. Thus, if the differences were made explicit along the way, there would be nothing to talk about. Note that one of the charms of Gibson's writing is his explanations for how his thinking has changed and why. If TSM similarly noted how they were changing Gibson's approach and why, there would nothing to talk out.

    For whatever reason, though, TSM (and especially T) are quite fond of orthodoxy, and do desire/demand/reward systematic followers. If they claim (which they sometimes do) that they are promoting a Gibsonian orthodoxy, then something disingenuous is occurring. The infraction may be minor, and worth only a little attention, but one update every 30 years still seems warranted ;- )

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  5. Eric, I think what you meant is that JJG was party to getting Cutting hire on at Cornell, not vice versa.

    --JJ

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  6. Quite right, I did mean the other way around. A little searching leads me to suspect I might be wrong. If Gibson was involved in hiring Cutting, it would have been at the very end of his life, and they were never colleagues. Cutting did not start at Cornell until 1980 (after prior stints at Yale and Wesleyan). With that in mind, the paper might have been intended as an homage of sorts, as an attempt to clarify what was distinctly Gibson in the context of changing views.

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  7. Yeah, I dug into that a bit too and quickly saw that it was unlikely JJG was involved in JC's hiring. But of course, EJG was at Cornell. And Cutting's approach has always been very eco/Gibson-friendly, but he was never, to my knowledge, a true believer. Kind of like Neisser.

    But it is reasonable, without having the man here himself, to speculate that JC saw, or thought he saw, a Turvey/Shaw movement away from the "purer faith" and thought it worthwhile to address it in print.

    --JLJ (Jim Jackson)

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  8. Eric,

    What would make this paper more useful to me at least would be some account of why there were differences between Gibson and T&S.

    So, for example, there is the observation that, "While Gibson’s perspective argues for direct perception being the normal, or at least natural, state of perception, it allows for indirect perception. In contrast, the Connecticut approach declares all perception to be direct (Cutting, 1982, p. 204)." Ok. So, what was the basis for this difference? For example, did the Conn's have some data that Gibson did not and that provided evidence against the Gibsonian position? If there was data, what was it? If there were an argument or reason, what was it?

    Thanks,
    Ken

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  9. Ken,
    Thank you for the feedback! I can try to work in a bit about the origin of the differences, but I am not sure I can provide more than speculation. At the time, TSM did not think they were doing something different than Gibson, and their views have not changed. Thus, it is impossible to ask them (or find them saying in print) why they chose to be different. My belief is that this denial-of-difference was virtuous at the start birth of the field, for social reasons. I find it odd that the denial continues.

    There is certainly not some pivotal piece of evidence in question (no evidence could show that all perception was direct). There are a string of successes, following perseverance, but that's not the same as proof.

    My guess is that the difference has to do with more fundamental assumptions about what scientists should be looking for and how to look for it. You can even occasionally catch Turvey asserting that his approach is the necessary way to go about doing the science (as a separate issue from it being True). Turvey is the unassailable king of empirical work in this field, but evaluating that assertion would brings us into the shifting sands of philosophy of science.

    I will try to develop this more fully.

    -------

    Frankly, I also think one reason for the shift was a change from approaching things from an American Philosophy perspective to a Continental Philosophy perspective. No one intended this to happen, it is just that Gibson's place in the tradition of American Philosophy is poorly understood... in part because American Philosophy is so poorly understood, and no one in the new generation had the background in it that he did.

    IMHO the debates of the '80's and early 90's were hopelessly confused because Gibson can only be properly defended in an America Philosophy context, which requires rejecting most of its critics premises, and TSM did not have the philosophical background to make that stand. I would really like to write something about that (and am hoping Tony, and a TBA Peirce scholar, might work on it with me one day). That work might be needed to more fully answer your question, but I think it is simply beyond the scope of this paper.

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  10. I'm also inclined to think that the TSM version of things grew out of their 1981 defence against Fodor & Pylyshyn. F&P's main objection was the 'shoeness' problem; if you could simply perceive the property of being a shoe, you could directly perceive shoes. TSM needed a principled way to rule this out, hence the move to ecological laws to underwrite what meaning gets into information and to the organism. Once you have laws and the resulting 'symmetry principle' underwriting meaning, you are then committed to only laws being enough; backing off slightly opens the door to a) indirect perception and b) shoeness, with the latter the real problem.

    Just a guess.

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  11. Hi, Eric,

    But, my point about the rationale for the differences goes beyond just the one example of the necessity of direct perception. It seems to me that introducing versus not introducing a lot of terms is not that theoretically enlightening. So, I guess my worry is that Cutting is setting a bad example for how to history of ecological psychology. He is not latching onto theoretically important or theoretically motivated distinctions. This is more like a catalogue of facts, rather than a helpful theoretical or experimental analysis.

    So, here's another example. I know that there is this dispositional approach to affordances and some relational approach to affordances. I vaguely get the difference, but why should I care? What is the theoretical or experimental payoff for one way versus the other? Can the relational approach solves the "shoeness" problem, for example?

    When I read Gibson, 1979, I get this vast edifice of theory, but I'm not at all sure why it is set up that way. What is the motivation?

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  12. Ken,
    Ah! Interesting.

    I suppose I think it is one job of the history of psychology to simply point out historic trajectories. For example, while I would not write a history of behaviorism in this manner, I do not think it is bad to have a history that simply points out how Hull's behaviorism was different than Tolman's or Skinner's or Guthrie's, etc.

    So far as I can tell, Gibson's theory does emerge out of a series of empirically driven insights. Either data revealed that phenomenon X did not work in the way people thought or attempting to nail down phenomenon Y with the methods of the day does not work, which required new experimental/conceptual advances. One problem with Gibson, is that he did not like to repeat himself. Thus you are correct, that the 1979 book does not lay this history out. This is part of the reason I think the '79 book is not the best place to start, it is ungrounded. But back on topic, the point is that I could tell the type of history you are looking for regarding the origins of ecological psychology.

    Alas, I could not tell the same sort of story regarding the differences between TSM and Gibson. I think Andrew is in part correct that some of the differences arose as TSM had to defend the ecological approach against the wave of new criticisms that appeared in the early 1980s.

    To more directly answer your "why care" question - it is hard to say why you would care. I believe that part of the reason the field has not fractured is because in most day-to-day circumstances that the working experimenter faces, it doesn't matter one bit whether you think of affordances as dispositions or as relations. Now, I believe that it does makes a significant difference when you try to put the big picture together.

    For an analogy: The correctness of Darwin's vs. Dawkin's vs. Jablonka and Lamb's vs. Wilson's versions of evolutionary theory also don't make much difference in the day-to-day life of the working biologist. The level of analysis at which it makes a difference is higher.

    Could you ask a follow up question? This feels like it is getting somewhere, but I'm not sure where to go.

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  13. I know that there are textbooks on stuff like "history and systems of psychology" and what makes so many of them seem to me to be so useless is that they merely say X thought P and Y thought Q. So, maybe that's not a bad thing, but it's not as helpful a thing as I, at least, would like. What, if any, reasons there are for this difference? A reason I would care about the difference is that it is motivated by some experimental finding, for example.

    Here is an example of something that would be interesting to me. Gibson thought that surfaces constitute affordances and that surface structure light, so that light coming from surfaces would specify affordances. That seems implausible to me and TSRM, 1980, offered a different picture. They thought that there are categorical properties that are manifest in affordances and that these categorical properties structure light, so that light coming from these categorical properties would specify affordances. But, why would TSRM think their approach helps? I see the problem for Gibson, but TSRM seem to me to have exactly the same problem. The problem is that you can't, in general, get a causal link between an affordance and the structure of light. Affordances don't, in general, structure light.

    So, some light on this issue would be helpful to me. By contrast, I don't see why anyone would care that TRM had lots of new words, where Gibson did not.

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    1. "Affordances don't, in general, structure light." I think this is a separate issue. I will try to put together a new post soon.

      One big difference between Gibson (as I read him) and TSM is the amount of dogmatism.

      As I read Gibson, there is energy bouncing around everywhere, there are patterns in that energy, some of the patterns are specific to the "objects and events" in the world. Some of those patterns are specific to things we might care about. Some of those can be detected. Some of those are detected... sometimes... when the circumstances are just right. Thus, there is the potential to directly perceive things, some of those things are affordances, and sometimes we actually directly perceive them.

      As I read TSM, you need to ditch all of that tentativeness, and all of the caveats.

      ------------

      Also, I agree about the simple observation of vocabulary being uninteresting. I need to mention it at least briefly, if I am following up on Cutting, because he mentioned it. For Cutting, the bigger problem how careful people were being in forming this new vocabulary. He felt that several of the new terms were creating tautologies or contradictions in undesirable ways.

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    2. To Ken: In fairness, Ken, I don't think you add in the "R" to T and S. I don't see Ed Reed ever being sympatico with the UConn school of ecological psychology.

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    3. Tony Chemero does this too; points out that Reed split some from the contents of the 1981 paper, ar least with respect to affordances. He keeps Bill Mace in there, though, so it's TSM.

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    4. Rob Withagen's recent paper on affordances inviting behavior directly references the Cutting paper (p. 252) and allies Reed with Gibson.

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    5. Cool, I will take a look. I like most of Rob's stuff. Of the stuff I have read, only parts I found weak were parts where I think he needs a little more of a James/Peirce approach.

      I definitely need to the part about affordances a little more, but I don't want the Cutting follow-up to become just another entry into the debates about affordances. Rather, I'm hoping to point out that the disagreement about affordances is often confused because it is a feature of the (largely) unacknowledged differences in approach.

      Even that needs to be kept light, I think, for American Psychologist. I don't want it to seem like I am just airing a niche disciplines dirty laundry.

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  14. And, you know, if you were to say that some theoretical difference does not make a difference in the actual practice of experimental work in eco psych, that would be helpful as well.

    So, for example, Gibson and TSRM sometimes say things like we need to reject ordinary physics and develop an ecological physics. Ok, but then I read a paper by Bingham and he seems to me to be using ordinary length, not some high falutin' ecological physical alternative. I have not read all that much eco psych, so I don't know if it is really true that this idea of eco physics is essentially a shield against criticism, but it does look that way on superficial examination. So, if someone sympathetic to eco psych would cover this, it would be more compelling.

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    1. I can't believe you still think ecological psychology isn't allowed to talk about physics.

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    2. Well.... the problem is that for many (maybe even "most") empirical problems, the direction of inquiry for a proponent of Gibson's approach and a proponent of the Connecticut approach would be virtually (if not "completely") identical. This is what I think Cutting didn't appreciate (and probably wasn't in a position to appreciate at the time). That is why the field hasn't fragmented.

      On the other hand, 1) Some people simply care if the theory is coherent / justifiable in the context of other beliefs / matching certain aesthetic qualities a scientific theory "should" have / etc. 2) Some people think the approaches lead to different directions of inquiry in the long term.

      Note: The history of "great discoveries" in physics includes many people particularly concerned with the issues in point 1, and not with the day to day worries of someone trying to figure out where a cannon ball will land.

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      Gibson's notion that we need an Ecological Optics (Ecological Acoustics, etc.), is very different than the more recent assertion that we need a broader Ecological Physics. I can defend the first claim all day long. The latter might well be a shield, I'm not sure.

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  15. Eric, in regard to your litany of "somes"...I agree with that reading of Gibson. The level of analysis needs to be considered. We DO NOT perceive everything (can everything even be defined? another problem for another day). We are, however, very successful at perceiving and acting upon much that is specified in the light/sound/etc.

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  16. Thanks for sharing this useful information.

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