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Individuating Experiences
I've been trying to work on the question about how we should individuate, or count, perceptual experiences at a time, and whether or not there is any substantive issue here.
   I am currently looking at my computer, and my desk, and a cup. Is this one visual experience, or three, and what decides this? Individuating experiences across sensory modalities seems an easier task, and we may just say that are as many experiences as there are senses, or something to that effect, but within a modality, things seem much harder to judge.
   The following may be various potential methods for individuating experiences at a time, that may be put to use: experiences might be individuated according to content&character, by the instantiation of phenomenal properties, by appeal to 'phenomenal articulation' to use a phrase of Tim Bayne's (this could also be spelled out by appeal to counterfactuals, i.e., 'if I could have had the same experience of the computer without the bottle, then they are separate experiences), by appeal to neural events, or by appeal to some facts about visual experiences, such as the fact that we cannot experience colour without shape, and so these properties must be within the same experience (it seems possible to do this with the other senses: we cannot perceive pitch without volume and timbre in audition, for example).
   My question is whether any of these methods of individuating experiences (at a time) reflect any substantive issue, or is there simply no carving nature at the joints here, and so we can safely individuate experiences only according to theoretical need.

The more general thinking behind this worry is that there seem to be consequences for the issue of the unity of consciousness, specifically the question of how we should think of phenomenal unity, or 'experienced togetherness'. Tye claims that the 'received view' of phenomenal unity, on which the issue is one of how individual experiences are unified, what relation holds between them,  and what the relation of the unified experiences to the maximal unifying experience is, is mistaken. Tye puts forward several criticisms of this received view, two of which come in the form of supposed infinite regresses that start once we posit a third experience that is responsible for unifying two experiences. Tye, on the other hand, claims that at a time a subject has simply one experience, which can be described in more or less fine-grained ways, and that the issue of how different experiences are phenomenally unified dissolves.
   if there is no substantive difference between methods of individuating experiences, my worry is that Tye's criticisms of the received view cannot be met with 'yes, but there has to be some relation that holds between experiences, as a subject does not have (in most cases) simply one experience at a time'.

Any thoughts on this greatly appreciated.  

Individuating Experiences
You raise a lot of issues here, but here is a thought. 

Your visual state comprises visual records of three objects.  (I use the term "visual record" just so as not to prejudge questions about how many experiences there are here.)  These records are separate -- there are three records -- at least in that they are separately responsive to changes in the scene that you are looking at: the cup can be tracked independently of the computer.  So even when the scene changes by the cup being removed, the computer can visually appear not to have moved.  There would in this case be a continuity in the computer-record, despite a change in the scene taken as a whole.  This seems to be an application of the Bayne counterfactual -- your visual record of the computer would persist unchanged even if your visual record of the scene or of the cup changed.  This would argue for a certain compositionality of visual records.

What Tye is saying about the unity of experience seems to based on a different criterion.  Your state of consciousness (again, I am deliberately not using the word 'experience') comprises all three records -- the three objects of your awareness are spatiotemporally related in your visual state in virtue of your awareness of them; your visual records of the three are all records of the same perceiving subject.  (cf. Kant's transcendental unity of apperception.)

What is an experience?  A state of consciousness or a visual record?  It would seem that these are differently individuated.  Different objects of visual awareness; same subject.

Does this distinction seem relevant?

Individuating Experiences

"Looking at" suggests something that takes some time.  Perhaps it can even get interrupted and then resume?  In any case, you are probably moving your eyes (saccading) and different objects are focused on.  There certainly seems to be a philosophical sense of "visual experience" that applies to the result of a succession of saccades, but I am honestly less clear about what it 'really' is and/or whether there's some fictionalizing about the whole idea.  It's also the case  that we don't have an uncontested neurophysiological theory about what is going on. 

Colleagues of mine in vision science are working on an aspect of the problem, anorthoscopic vision, and we've had a number of discussions, so my ignorance here isn't entirely a matter of being uninformed.  

Individuating Experiences
S.A.C.:I've been trying to work on the question about how we should individuate, or count, perceptual experiences at a time, and whether or not there is any substantive issue here. 

Jo E: I think there is a substantive issue here, and a very interesting one. However, I think it is important to make sure that the right form of analysis is used. The analysis we use for physical dynamic processes, which are essentially heuristic tools for predicting experiences, should not be expected to apply to experiences themselves. A photograph of a cup, a computer and a desk can be cut into three bits. There is no such thing as cutting experiences into bits. I think Tye is right on this one, even if maybe not on other issues. (I am not sure that there is a received view here, is there?) Fundamentally, 'togetherness' is not a concept with any meaning in physics. There is proximity and there is adhesion but togetherness is a 'felt' concept that seems to work both for bunches of flowers 'in the world' and experiences of bunches of flowers but does not have the same meaning in the two situations, just as the yellowness of the flowers in terms of reflectivity is not the sensed yellowness. 

The way experiences can be complex unities is something I am particularly interested in. What seems pretty clear from work on optical illusions is that they are not 'put together' in any Lego brick sort of way in pixels or voxels. I strongly suspect that you can get experiences of colour without form and pitch without volume. Walking in the park, I may remark 'what a striking pink those tulips are'. I will have experienced a single hue as belonging to a number of flowers, despite the fact that what my retina receives is a grossly heterogeneous range of shades and hues in a pattern relating to an uncountable number of blooms forming a shape I am really not aware of, and somewhere in my parietal cortex a message has been generated that tells another part of my brain that there are 'lots of flowers of the same colour'. I am pretty sure that our experiences are built out of conceptual elements like this, not pixels, and these conceptual elements relate in a way that words do, not Lego bricks. This really the only way you can make sense of the sorts of illusion people like Purves and Lotto have presented. There are no 'parts'. Interestingly, there are probably no 'parts' in theoretical physics any more. 'Part' is another folk concept, I suspect.

This analysis may worry those who feel that if experiences are based on physical dynamic processes they should be 'put together' in the same way. However, that is not how physics tends to work. In a physical explanation the explanatory account of the dynamics which predicts an observation is put together in a different way from the account of the observation itself. This is Bohr's comlementarity. Bohr also believed there was another complementarity for experiential descriptions such that they had to be put together in yet a third way. This seems to be true because there are lots of experiential concepts that have no physical equivalent - and could not have because they do not suit the metrics of physics. Loneliness is an example. That is not to say that we need any spooky dualism, just a recognition that ordinary natural science requires several unmixable accounts of the world.


Individuating Experiences
When I'm "looking at my computer, and my desk, and a cup," I experience a complex content (involving features of at least these three things). But why say that in addition to this complex content there is also a complex experience of it (where an experience is a conscious state and where 'complex experience' means an experience with experiences among its parts)? The phenomenological complexity requires us to acknowledge the complex content, but what extra mileage do we get by positing a parallel complexity in the experience of it? On the face of it, a complex experience wouldn't do any better at accounting for the unity of consciousness. Given parsimony, we shouldn't posit such complexity unless there's a good reason to do so.

In fact, a complex experience seems only to lead to more difficulties. For instance, on an experiential parts view, my experience of the cup, computer and desk would include an experience of (just) the cup, an experience of (just) the computer and one of (just) the desk. First off, it might strike some that this doesn't fit the phenomenology (arguably I don't have, tucked inside my 'larger' experience, an experience of just the cup). More importantly, we now have to figure out how, from the combination of these three component experiences, I derive an experience of the cup, computer and desk together (an issue which, I think, Mohan Matthen alludes to above as concerning the transc. unity of apperception). After all, a combination of experiences is not the experience of a combination. To use William James' example, "Take a sentence of a dozen words, take twelve men, and to each one word. Then stand the men in a row or jam them in a bunch, and let each think of his word as intently as he will; nowhere will there be a consciousness of the whole sentence" (William James, Principles of Psychology, vol. 1, p.160). More abstractly (on p. 161), James says, "Idea of A + idea of B is not identical with idea of (A+B)." We need some relation that combines experiences in such a way as to yield unified consciousness of their contents.

So, one argument against counting experiences more finely is that by doing so we gain nothing and introduce more problems.

I think this line fits nicely with Tye's 'transparency' (or representationalist) account of consciousness. Intuitively, it's tempting to respond to Tye by introspecting and noting the evident complexity in one's experience. But representationalists can reply (if I interpret them correctly) that all of that complexity of which one is aware in introspection pertains just to the content of one's awareness at the time, and not to the experience whereby one becomes aware of it. Perhaps, then, we can find reasons for counting experiences more finely if representationalism turns out to be false.

Incidentally, another phil of mind debate where it's important to clarify how to count mental states more generally (not just conscious states) is that between D. M. Rosenthal and some of his critics (esp. Uriah Kriegel) -- Rosenthal says that a higher-order thought is distinct from the lower-order state that it makes conscious since these higher- and lower-order mental states have different contents; but Kriegel and others maintain that one self-representing mental state can 'carry' both these contents.

Individuating Experiences


In my upcoming paper, On the Theoretical generation of Antinomies and Paradoxes, I write:

Empirical research suggests that the lowest higher-order representation that humans normally seem to be aware of is the one in which the major sensory elements are bound up into a single conscious whole.  Within our visual field, for example, in her book Exploring Consciousness Rita Carter states that “[…] we see color… form, location, (movement)[1]...and so on,  all in one - not as separate elements” (2002, p. 34).  Additionally, cognitive researchers have known for quite some time that despite the billions upon billions of neurons and tens of trillions of synapses, the maximum number of abstract representations or categories that the mind is consciously aware of at any one time seems to only be four or five.  We know that the brain processes massive amounts of raw sensory data in bits and pieces before binding it together and brings only the timeliest and most important information into focus.  We also know that on the conscious level of awareness the brain assesses this information in only four or five separate concepts or components.  But why does the brain selectively deliver everything into consciousness already bound up in a single whole?  And why, despite the immense processing power available, do we only keep four or five things or categories in conscious awareness at any one time?  Why not ten, or a hundred, or even a thousand?  To date no one has provided a compelling explanation for these two puzzling facets of human cognition. 

My earlier investigation (Acosta, 2006, pp. 151-165) indicating that fundamental data may ultimately be transformed into conscious symbolic meaning and knowledge through a complex refining process, whereby basic information is filtered up through an iterated hierarchical contextual continuum, may provide an answer.  Referring back to the underlying structure of games, we recall that the contextual framework of games and number theory are simply abstract and more complex parallels to, and permutations of, the four macro properties of the universe (space, matter, motion, and time) plus the original causal objective of all life.  Each successive slightly more complex iteration of the primal frame of reference, form the basis for an interconnecting and interacting continuum of essential information within which a given chaotic knowledge system develops.  

This fact alone may explain why the brain always presents conscious information as a single whole.  The single whole in question refers to a particular abstract frame of reference viewed as complete representation, while the four or five distinct categories of basic information of which we are aware would individually equate to different expressions of the five criteria of the original frame of reference when viewed separately.  To recapitulate, the frame of reference of a game consists of: 

  1. Field
  2. Element(s)
  3. Rule(s)
  4. Objective(s)
  5. Feedback Loop

· A field may be defined as a static, non-moving bounded area of space in or on which the elements move. (1) 

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· Elements are objects that move, or are caused to move, along or within a field. (2) 


· Rules, i.e., the action component, are descriptions of how the elements are positioned in space, and move or are caused to move in relation to the field and relative to each other. (3) 


· The objective is the underlying rationale that initiates an action, resulting in a gain or a loss, or which can be perceived in the more general positive and negative terms of a concept and its opposite. (4) 


· The feedback loop is any action or reaction to the prior movement of elements within the field over time. (5)  (Note: when an object changes position along or within the field we contextually perceive this movement in terms of a span or duration of time.  Accordingly, the “fourth dimension” of the physical universe is implicitly understood to be an operational element of the frame of reference of any game.) [2] 


You are having one perceptual experience corresponding to your visual field.  Within it you are identifying three objects, i.e., computer, desk, and cup.  There is no motion to speak of, so the rules component does not come in to play.  The objective category would be depend on whether you began typing on your computer, opened your desk drawer, or picked up your cup.  The resultant perceptual feedback would depend on your exact choice.

    [1] It is assumed that the phrase, “and so on” includes motion, which is why the term “movement” was inserted by this author. 

    [2] When physicists describe time as the fourth-dimension, they have in mind the three spatial dimensions of height, length, and width combined with time.  By contrast, the term “fourth dimension” as utilized in this paper is meant to convey the four macro properties of space, matter, motion, and time, also with time as the fourth but distinct element in the series.  My convention is intended to emphasize the temporal dimension in a manner that is more in keeping with the way it is subjectively perceived. 


Individuating Experiences
Thanks for the comments.

Mohan: I think that the distinction you point to is relevant, and in fact may provide some support for the position that we can individuate experiences more finely than Tye claims. Given that these visual records will have different individuation conditions from the states of consciousness, and that they are also at least in principle separable from one another (though I think this depends on whether or not the spatial relations between the objects are represented, i.e. is the computer represented as being to the right of the cup, and if so, then it may not be separable when we apply the counterfactual test), then this perhaps puts pressure on Tye's claims that experiences are not divisible into smaller parts.

Also, we might use this distinction to say that regardless of which of these (visual record or state of consciousness) we call the 'experience' (Tye will claim that it is the state of consciousness), we still need some explanation of how it is that these visual records are unified, and so the question of phenomenal unity might re-appear as there are still parts that need to be unified to form a whole.

Also, for what it's worth, I think that of the possible criteria for experience individuation I mentioned above, the counterfactual test is the most promising (and more than one of the other criteria collapse into this one). The results of this test when we apply it within a sensory modality will depende on how we think the relations between the objects of our experience are represented though: for example, if the computer is represented as being to the right of the cup, and this 'to the right' is part of the representation, then if we ask 'could I have had the very same experience of the computer, in the absence of the cup, then we might think the answer is 'no'. This may mean that within a sensory modality, the counterfactual test will still always yield the result that we have only one experience at a time. Across modalities however, it seems far more likely that the counterfactual test will tell us that we have six experiences (or an experience per sensory modality). If we can individuate experiences this finely, then the question to Tye or a representationalist of a similar stripe would be 'don't we still need to account for the unity of these six experiences?' 

Individuating Experiences

From vision to sounds.

When I play the piano my two hands touch the keyboard, sometimes my two feet touch the pedals and I constantly move my body. When my two hands touch the keyboard I clearly live  two experiences, two hands one body, one subject. But I also live an integrated experience with all the components. I clearly feel an interaction between my body and the instrument. Then I live the experience of projecting my mind into the future when I improvise.

I see my hands on the keyboard,  I see them touching the black and the yellowish ivory keys. I can close my eyes and keep playing and touching the keys and inside my mind I will see the paths where the improvisation is taking me. Sometimes I can smell the  wood of the piano, I feel  my cat moving around, see the red bricks of the wall.

The only way to experience my auditory cortex seems to be when I hear the sounds of the music I am playing, and feel their impact in my body.

The process of making music combines my experiences. This is definitively a carnal integrated series of experiences with various elements.  (Integration of mind and body).

There is a togetherness in the musical act. Togetherness does not mean the simultaneity of cognitive events (or is it the illusion of simultaneity?) Is consciousness the integration of information as does suggest Giulio Tononi? Phenomenal unity or a series of micro-consciousness? But then how do you bind the micro-consciousness?

When I introspect my musical experiences, I live the experience of living the experience, no transparency for me here.

When I walk the streets of  Brooklyn I can hear the music in my mind but there is no volume, no sound. It’s there allright, no question. Is the pitch really silent? In some cases of verbal hallucination you can hear the words but there is no sound.

Luc Delannoy

Individuating Experiences
hi stuart,

    let's suppose that experiences are states, since you asked about experiences at a time. on this assumption,  one way hear the question about how to individuate experiences is like this:

   first assume some theory of what experiences are, such as phenomenal states (e.g., states individuated by their phenomenal character), or perceptual states (e.g., seeing a bug, or seeing Barb the bug, or seeing Barb when she looks creepy, or seeing that Barb is creepy), or states with a special kind of content (perhaps contents that cluster together, as in your example of color and shape [btw, i think you meant to write that we can't experience shape without color, not that we can't experience color without shape]. there are probably other plausible options as well.

  then ask: which pairs of states are instances of the same experience?   on this interpretation of the question, it seems like the main issue is settled already at the first step. eg, take a state of seeing Barb the bug and the state of seeing twin-Barb. if you ask whether these states are instances of the same experience, you'll get pretty different answers depending on whether seeing a bug as an experience, or seeing Barb, or (on internalist theories of phenomenal character) being in a phenomenal state that can be shared by seeing Barb and seeing twin-Barb.

    on this interpretation, the question more or less reduces to the question of what experiences are.  fwiw, to me it seems reasonable to allow multiple kinds of states to count as experiences. if so, then there isn't any more of a substantive issue about individuation per se, beyond whatever substantive issues are involved in deciding which states can be experiences. but deciding that does seem substantive.

   a different way to hear the question about individuation is: given an overall conscious state of a subject at a time, are there places at which this overall state can be carved at the joints? 

    here it seems like there might be a variety of different kinds of joints. phenomenal states, perceptual states, either of those within a modality, and certain cross-modal states all seem like good candidates.

   i guess i'm inclined to reject both of your options  (viz: "(i) any of these methods of individuating experiences (at a time) reflect a substantive issue, vs. (ii) there simply no carving nature at the joints here, and so we can safely individuate experiences only according to theoretical need") for both interpretations of the question. against (ii), there are ways to carve experiences at the joints, but against (i) - or at least, against what seems to be an assumption in the vicinity of (i) - there isn't a unique set of joints.



Individuating Experiences
Hi dudes,
Anne Jacobson makes an extremely important point here, which I would like to generalize and expand on.

Let us distinguish "perceptual states" from "perceptual actions". Examples of types of the former are _seeing something red_, _seeing this cup_, _seeing a red cup next to a white saucer with a visual system in condition C_, and perhaps _visually representing that p_. Examples of types of the latter are Anne's _looking at this cup_, as well as _watching this frog_, and _looking around this open house_. 

If we are willing to help ourselves to the slightest bit of ordinary metaphysics, it is easy to draw a sharp theoretical distinction between these categories. Perceptual acts are *actions* in the strictest ordinary sense (voluntary, reasonably praised and blamed about etc); and therefore essentially dynamic (entailing consequences for the past and future). Perceptual states are static (not entailing such consequences); and therefore not actions in any noncontrived sense.

So a first line answer to Stuart's question is this: 

1) Facts about the diachronic individuation of acts (and other natural processes more generally) are relatively clear prima facie. Modulo the statue-clay type Davidsonian whine about flipping light switches, the same is true for their synchronic individuation.

2) In general, facts about the individuation of states seem to be rather less clear (semanticists sometimes put this by analogizing states/events to masses/objects). David Lewis: "we have beliefs the way we have the blues". These or those theoretical purposes allow arbitrary agglomeration and slicing synchronically and diachronically.

Accordingly, we should say that if it is perceptual acts that are at issue, there are substantive questions to be asked (and relatively easily answered), whereas if it is perceptual states are at issue, we might have theoretical motivations for doing it this or that way but none of these would abuse joints in nature.

** What about the theoretical purpose of assessing claims about the unity of consciousness?

Well: in my view, it can be argued that the types of experience are the same as the types of action. Grant me this: then perceptual states are not experiences (despite the near-universal tendency of my honored colleagues to refer to them as such); if any things deserve the name 'perceptual experience', they are the perceptual actions.

So Tye's view that considerations from the unity of consciousness can resolve questions about the individuation of perceptual states is, sadly, in error. By contrast, if the unity of consciousness is best understood stemming from an ontic priority among experiences of the whole over its parts, we can say that one's most fundamental experience is a very big, long, complex act: one's "conscious life". In Schaffer's terms, this is a "priority monism" view, rather than the "existence monism" we find in Tye.

Individuating Experiences

May I disagree with Benj ?

Seeing something black (the piano) is an action, it involves brain processes and they are actions; such biological processes have psychological consequences. Brain processes are, or are the cause of, mental states. Looking at a black piano is also an action but it might imply desire, volition, attention and concentration, and more complex brain processes (actions).  I am not sure about the sharp distinction as Benj put it. Hearing and listening to music are both actions; perceptual actions with perceptual states, the latter being conscious or not. I guess I have a hard time with the use of the word static. My 2 cents.

Individuating Experiences
We might consider Frege's 'intuitive criterion of difference' (Evans (1983) to be relevant here: that two thoughts are distinct just in case a subject could (assuming ideal rationality) accept one while denying the other. Applied to perceptual experiences this might amount to their individuation according to the criterion: that two perceptual experiences are distinct just in case a subject could (assuming an ideal memory) accept that he had experienced the one while denying that he had experienced the other. This suggests that another substantive issue is at stake here: whether experiences are to be individuated as personal level or subpersonal level states. If experiences can be subpersonal, then Frege's criterion couldn't be invoked, but if they can't, then it could. 

Individuating Experiences
Thanks, Benj!  I confess I'm very puzzled by the discussion.

I think visual experience is really not at all like what we think it is.  The important thing about vision is that it works; in working it may be more whacky than we think.

It turns out that many ordinary people, and some philosophers, think of vision as giving us something like photographs of items in our environment.  A challenge to this is  Mach's idea that what we get is a scene shaped by the differences in perspective.  Both of these are quite wrong, if we think of what we take in at one look.  Vision is usually focused like a spotlight, by and large, and we get sucessions of very small takes.  In addition, recent research on anorthoscopic vision suggests that we put these together into something like a sense of the scene.  Let me  give an example of a dramatic sort of case:  the camel behind the split.

Suppose you are looking at a screen with a slit in it, behind which a camel is passing.  What you see is camel stages, we might want to insist.  However, at the end you get what you really want to say is something like a whole-camel percept.  But of course, since the whole camel was never present, we might feel unhappy about saying you actually saw the whole camel at some one time; one thing that's interesting is that we can't put it all together if we are clueless about what we are seeing..

Noe, many of you will remember, thinks that the idea that we see the whole thing is a product in part of our sensory motor skills.  I'm not sure that's true, but I am pretty sure that the idea of one visual experience of three objects really needs explaining.  I doubt you have  something static enough to describe; that is, it changes all the  time, more quickly than you can describe it.  That doesn't mean there isn't a description that is correct at one time, of course, but what you are describing may well not be what has the roles visual experience is supposed to have - e.g., the epistemic roles. 

One complication:  According to Anne Triesman, we can have a more global focus on a scene, but then what we get experientially is not the actual objects before us but a Bayesian product that give us something like the averages.  What we get in global vision is probably just great for some kinds of actions, but it may not be so great for telling us the real truth about the environment.

I can't now see the previous comments, but let me remark about the one before me that it might not be a good idea to relate content to reports.  A lot of our reports of what we see at some one time are really suspect.  Perceptions does not give us pictures.

Individuating Experiences
the best prophylactic is always to substitute feeling for experience (or consciousness). You can probably carve up feelings right down to JNDs, but they're best thought of as continuous, with a specious ongoing portion grading off into a fast fading memory wake behind and a fuzzy-bounded wave-front ahead... The carving up is categorization of felt content.

Individuating Experiences
Reply to Anne Jacobson

A J Wrote: "Suppose you are looking at a screen with a slit in it, behind which a camel is passing.  What you see is camel stages, we might want to insist.  However, at the end you get what you really want to say is something like a whole-camel percept.  But of course, since the whole camel was never present, we might feel unhappy about saying you actually saw the whole camel at some one time; one thing that's interesting is that we can't put it all together if we are clueless about what we are seeing."

A T: In  fact we can put it all together even though we might be clueless before we put it together. Consider the following experiment that I conducted a few years ago (A. Trehub. The Cognitive Brain. MIT Press, 1991).

Seeing-More-Than-Is-There (SMTT)

If a narrow vertically oriented aperture in an otherwise occluding screen is fixated while a visual pattern is moved back and forth behind it, the entire pattern may be seen even though at any instant only a tiny fragment of the pattern is exposed within the aperture.


1. Subjects sit in front of an opaque screen having a long vertical slit with a very narrow width, as an aperture in the middle of the screen. Directly behind the slit is a computer screen, on which any kind of figure can be displayed and set in motion. A triangular-shaped figure in a contour with a width much longer than its height is displayed on the computer. Subjects fixate the center of the aperture and report that they see two tiny line segements, one above the other on the vertical meridian. This perception corresponds to the actual stimulus falling on the retinas (the veridical optical projection of the state of the world as it appears to the observer).

2. The subject is given a control device which can set the triangle on the computer screen behind the aperture in horizontal reciprocating motion (horizontal oscillation) so that the triangle passes beyond the slit in a sequence of alternating directions. A clockwise turn of the controller increases the frequency of the horizontal oscillation. A counter-clockwise turn of the controller decreases the frequency of the oscillation. The subject starts the hidden triangle in motion and gradually increases its frequency of horizontal oscillation.


As soon as the figure is in motion, subjects report that they see, near the bottom of the slit, a tiny line segment which remains stable, and another line segment in vertical oscillation above it.

As subjects continue to increase the frequency of horizontal oscillation of the almost completely occluded figure there is a profound change in their experience of the visual stimulus.

At an oscillation of ~ 2 cycles/sec (~ 250 ms/sweep), subjects report that they suddenly see a complete triangle moving horizontally back and forth instead of the vertically oscillating line segment they had previously seen. This perception of a complete triangle in horizontal motion is strikingly different from the line segment oscillating up and down above a fixed line segment which is the real visual stimulus on the retinas.

As subjects increase the frequency of oscillation of the hidden figure, they observe that the length of the base of the perceived triangle decreases while its height remains constant. Using the rate controller, the subject reports that he can enlarge or reduce the base of the triangle he sees, by turning the knob counter-clockwise (slower) or 
clockwise (faster).

3. The experimenter asks the subject to adjust the base of the perceived triangle so that the length of its base appears equal to its height.


As the experimenter varies the actual height of the hidden triangle, subjects successfully vary its oscillation rate to maintain approximate base-height equality, i.e. lowering its rate as its height increases, and increasing its rate as its height decreases.

This experiment demonstrates that the human brain has internal mechanisms that can construct accurate analog representations of the external world. Notice that when the hidden figure oscillated at less than 2 cycles/sec, the observer experienced an event (the vertically oscillating line segment) that corresponded to the visible event on the plane of the opaque screen. But when the hidden figure oscillated at a rate greater than 2 cycles/sec., the observer experienced an internally constructed event (the horizontally oscillating triangle) that corresponded to the almost totally occluded event behind the screen.

The experiment also demonstrates that the human brain has internal mechanisms that can accurately track relational properties of the external world in an analog fashion. Notice that the observer was able to maintain an approximately fixed one-to-one ratio of height to width of the perceived triangle as the height of the hidden triangle was independently varied by the experimenter.

These and other empirical findings obtained by this experimental paradigm were predicted by the neuronal structure and dynamics of the putative retinoid system, a system of brain mechanisms that was originally proposed to explain our basic phenomenal experience and adaptive behavior in 3D egocentric space (Trehub, 1991). It seems to me that these experimental findings provide conclusive evidence that the human brain does indeed construct analog representations of the external world.

The key message is this:

The retinoid system created a vivid conscious experience of an object undergoing a series of systematic spatial transformations when the object and the events that were consciously experienced were not a part of the exteroceptive visual world of the observer. This striking experimental outcome was predicted by the theoretical neuronal structure and dynamics of the retinoid model.

Individuating Experiences
Arnold, I'm embarrassed.  I think you did catch me out.  Obviously, you can get from the experience some knowledge of what you are experiencing. 

In fact, I was thinking of a talk given by a vision group at Univ of Houston, and I think the point was that you couldn't get an experience of the whole thing if you couldn't put it togther before or during; the contrast was with an array of dots which couldn't or wasn't seen as a pattern.  Perhaps, though, I should confess that it is this talk I'm relying on - along with a bunch of their articles - and my memory is faulty.


Individuating Experiences

[Edmond Wright]  I am naturally with Luc Delannoy in reminding us that the selection of a portion of a sensory field (visual or other) is a matter of ‘desire, volition, concentration and attention’.  Those four would be better rendered generally under ‘motivation’.  At the animal level, the brain of the organism is geared to embed in memory portions of fields that accompany pain or pleasure experiences as gestalt-unities.  Pain embeds them marked with fear, pleasure with desire, which provides the motivational element that spurs the organism to future would-be appropriate action, be it at first no more than advance or retreat. 


It needs saying that the etymology of the word ‘motivation’ reminds us that motion in the service of bodily/species maintenance is what is at the core of the process.  This is the sense in which we can see one relevance of Noe’s drawing our attention to the sensorimotor aspect.  Initially these can only be ad hoc embeddings that may or may not succeed;  later encounters with that same portion of the field may or may not refine the response, but evolution does seem to have favoured the continual rejigging of the gestalt, in an endless open provisionality.  For the unity of the gestalt is no more than a tentative feature of the process, for the organism may be forced to rejig the memory with a radical transformation of the gestalt, for example, replacing what was taken for a ‘single’ entity in the real with two others, or two-and-a-bit others, or none at all (see my discussion of this at length in my contribution to The Case for Qualia (Cambridge MA : MIT Press, 2008, pp. 35-60) and my chapter on ontology in Narrative, Perception, Language, and Faith (Basingstoke: Macmillan, 2005, pp. 103-20).  Gestalt-unity is no guarantee of singular entityhood in the real as good conjurors know well.  For this reason it is unwise to hang a theory of perception on a belief in given. ‘transparent’, external ‘unities’, be they supposed ‘objects’, ‘persons’ or ‘selves’.


As distinct from the animal organism (as it may still half-survive in our reptilian brain), we human beings made ourselves human by learning how to update, hopefully, each other’s gestalts.  The refinement process became no longer just an outcome of a chance encounter by the solitary organism, bound to the conditioning regime.  Co-operating groups (from two members upwards) discovered how to take advantage of Michael Tomasello’s ‘joint attentional scenes’ (Tomasello, Origins of Human Communication, MIT Press, 2008);  for how the anthropologist Gregory Bateson’s notion of play clarifies the process, see URL  They are certainly 'scenes', acted out, performed, because the ideal focus of the game, required to enable the talkers to home in on roughly the same region of the real and improve their co-ordination in action, owes its singularity to their mutual imagining.  

It is interesting to see that Tomasello himself never questions the existence in the real of the ideal singular focus (Tomasello, pp.74-80).  The real exists all right as the field over which our differing perspectives range, but not the ideal, perfect superimposition of them all.  Even when we admit that our perspectives are 'vague', there is no guarantee that the criteria that we take for granted in our vague conceptualizing overlap completely with those of others.  One person's view of the 'vagueness' is not the same as that of others, as David Wiggins seems to think (Wiggins, ‘On Singling out an Object Determinately’, in Philip Pettit and John MacDowell (eds.), Subject, Thought  and Context. Oxford, Clarendon Press, pp. 169-80).  Grice made the same error, for he never wondered whether the hearer's intention might not match that of the speaker.  Sir Alan Gardiner, who anticipated Grice cooperative notion by many years, saw the problem clearly (The Theory of Speech and Language, Oxford: Clarendon Press, p. 80).

Arnold Trehub’s ingenious experiment highlights the brain’s fondness for constructing a provisional gestalt out of surprising sensory qualia.  It also demonstrates how the ‘countability’ S. A. Crutchfield is in search of is merely an essential device, a kind of catalyst in the knowledge process, its deliverances always expendable, revisable.  Hence, singular entityhood constitutes no metaphysical ground.  God is no mathematician.

Individuating Experiences
Dear All,

Firstly, thanks for all the comments on this issue. I think that I'm now inclined to accept Susanna's diagnosis of the issue: that there are various potential joints at which we might carve experiences, at a time, and several of you have identified such potential joints (though several suggestions seem more relevant to the question of individuating experiences diachronically, which is an importantly different question). However, I also agree with Susanna's inclination to reject the claim that there are any unique set of joints according to which we should carve up experiences synchronically. On this view then, we have various potential methods of counting or individuating experiences at a time: we can carve up a subject's overall conscious state at a time into perceptual states, phenomenal states, states that correspond to a sense-modality, and some cross-modal states, but none of these potential methods reflect a unique set of joints at which we should carve the subject's overall conscious state.

Though there are no unique set of joints, I do however think that there are limits to the carving. Though we can legitimately divide up experiences to correspond to the different sense modalities, there are certain divisions that we cannot make, due to facts about perceptual experiences. We cannot, for example, divide up experiences so as to have a visual experience that represents shape without colour. There would seem to be other likely limits, corresponding to the other senses, for example, we could not divide things so as to have an auditory experience that represented pitch without volume or timbre, or indeed any one of these three properties without the other two.

How this relates back to questions of the phenomenal unity of perceptual experience at a time is as follows: Tye identifies what he claims is a 'received view' on this issue (held by Time Bayne, David Chalmers and Barry Dainton), on which a subject has at a time, several perceptual experiences that can be phenomenally unified, and so some relation of phenomenal unity is posited to explain this. Tye, on the other hand, rejects the claims that a subject has several experiences at a time. Instead, a subject has just one experience, the content of which we can describe in more or less fine-grained ways. This view, coupled with claims about the transparency of experience, mean that Tye claims that the question of how several (sense-specific) experiences had by a subject at a time are phenomenally unified dissolves. So, part of Tye's view would seem to be that we cannot legitimately divide up a subject's overall conscious state at a time into 'smaller' states, and that nature's joints here admit of only one experience per subject at a time. Given this, and the 'received view' theorists view that at a time a subject does have several experiences that are unified by some phenomenal unity relation, it seems to matter who here has nature's joints on their side.

Given however, that I am taking Susanna's view, and holding that there are various joints, but no unique set, then independent reasons will be needed to reject either Tye's 'one experience' view, or the received view of phenomenal unity. As it happens, it also seems as though Tye does take himself to have nature's joints on his side here, given his claims about a subject's overall experience at a time not having any experiences as its proper parts... (Benj is right here, when it comes to experiences, Tye seems to be some kind of existence monist).

Individuating Experiences
Could it be that the differences between the phenomenological and physical conceptions of time and space make them incommensurable systems? (as Wittgenstein suggests in the Big Typescript - p. 521).  I guess I'm wondering whether there can be any such thing as a phenomenological language of experience that is not inherently self-contradictory.  There may not be any substantive issue here inasmuch as attempts to individuate and count elements in the content of my experience (computers, desks, cups, etc.) suggest a carving up of experience that does appear to go beyond theoretical need.

The clue that we may be offending against parsimony here comes with the discussion of Tim Bayle's term "phenomenal articulation".  It seems to be a fact that 'we cannot experience color without shape, perceived pitch without volume or timbre without audition', but if, for example pitch cannot be imagined without volume these qualities are internally (intrinsically) related to each other.  Internal relations are not genuine relations.  If I cannot imagine one quality of a perceived object without the other I cannot imagine the object at all.  Consequently any observation of these qualities' intrinsic connections would have a tautological character that prevents it from rising to the status of a genuine assertion of fact. 

When James gave the Gifford Lectures, his original opening paragraph (which was not included in the eventual publication of Varieties...) contains many passages that bear on this discussion of 'perceptual experience at a time'.  I found it in The Thought and Character of William James, Briefer Version ( Perry, R. B. Harper&Row, Pubs., 1935, p. 258)  The paragraph is far too long to quote in full but two sentences stand out:  "The moment stands and contains and sums up all things; and all change is within it, much as the developing landscape with all it's growth falls forever within the rear windowpane of the last car of a train that is speeding on its headlong way.  This self-sustaining in the midst of self-removal, which characterizes all reality and fact, is something absolutely foreign to the nature of language, and even to the nature of logic, commonly so-called".  The entire paragraph bears reading.


Individuating Experiences

I believe the choice is up to the could be one  visual experience  or three, there's no reason for one to be wrong and one to be right,why create divisive opinions dismissing the possibility of unity.

Individuating Experiences
The following paper might be of interest:
Brian L. Keeley "Making Sense of the Senses: Individuating Modalities in Humans and Other Animals"  The Journal of Philosophy Vol. 99, No. 1. (Jan., 2002), pp. 5-28.


Individuating Experiences
You might want to take a look at The Pragmatics of Cognition, pp. 300-301 in The Cognitive Brain, MIT Press (1991).

Individuating Experiences
Reply to Phil Dubuque
'Could it be that the differences between the phenomenological and physical conceptions of time and space make them incommensurable systems? (as Wittgenstein suggests in the Big Typescript - p. 521).'

Indeed, Phil, I would take that as axiomatic and more to do with Bohr than Wittgenstein (and of course there are two incommensurable 'physical' conceptions of time and space already, according to complementarity!).

Individuating Experiences
On the general question of 'subjective' and 'objective' individuation, I find the brief article by G. Simondon, "The Position of the Problem of Ontogenesis"  (English translation by G. Flanders recently published in the online journal Parrhesia, Number 7, 2009; 4-16), particularly interesting and full of possibilities.