Associative and Dissociative Networks in Cognition
The modern conception of a monadic mind in terms of cogito was introduced by Descartes. Being aware of the double nature of the sensory organs of the brain, he had to suggest a seat for the unity of the soul:
"...the other parts of the brain are all of them double, just as we have two eyes, two hands, two ears, and finally all the organs of our outside senses are double; and inasmuch as we have but one solitary and simple thought of one particular thing at one and the same moment, it must necessarily be the case that there must somewhere be a place where the two images which comes to us by the two eyes...can unite before arriving at the soul, in order that they may not represent to it two objects instead of one....there are no other place in the body where they be thus united unless they are so in the gland."(Descartes, 1649)3
His assignment of this unifying role to the pineal gland was soon discarded. But the more general mind-brain problem that Descartes raises remains a controversial issue. Most of the time one feels
oneself to be of a single mind, not divided, irrespective of the facts of asymmetry and partial complementarity between the two cerebral hemispheres revealed by brain studies. Even when Sperry and others have uncovered the mediating function of corpus callosum one continues to ask about how coherence of visual processing comes about. We may still ask with Descartes: Why is it that we (normally) see one image, not two?
He raised this question in "Passions of the Soul" in 1649. Centuries later the almost opposite question was raised with reference to figures inviting visual ambiguity such as Necker's cube, Rubin's vase, or the rabbit-duck figure: How is it that we are able to shift between two rival images of the "same" form? How does such discriminational coherence and alternating come about? What are the processes involved in coherent perception and understanding? Is conscious attention a unified or divided activity?
Such questions are pursued in cognitive psychology in terms of schemata (Neisser, 1967, 1979), in psychobiology and neuroscience in terms of emergent properties and downward causation (Sperry, 1965, 1969, 1988) and cortical self-organization (Singer, 1990), and in general psychology in terms of association and dissociation (Hilgard, 1986. A concern with self-organizing systems and associative networks, first proposed by James and Hebb may also be recognized in neurocomputational modelling (Fukushima 1975; Malsburg, 1973; Rummerhart and Zipser, 1985). In the following I shall indicate how such questions are dealt with in terms of different frames of reference, refer to neurocomputational explorations of visual ambiguity, and relate to the thesis of the mind as a self-organizing dyad involving the participation of a virtual other. Towards the end I shall indicate how the thesis may account for the "hidden observer" disclosed and discussed by Hilgard in terms of dissociation theory, and how it relates to a controversial issue on the nature of consciousness brought about by the studies of "split-brain" paitents.
A pioneer in the field of neurocomputation, Warren Mcsuper4
In his later work Malsburg has proceeded to attack the problem of how neurons distributed according to orientation preference in spatially separate columns can give rise to vision of a coherent figure, separated from a background, and the even more difficult problem of separating different superposed figures from a scene that invites visual ambiguity. He proposes that a coherent image comes about through temporal coherence of the firing of neurons, exhibiting synchrony in spite of their locations in distant columns. When there are two superposed figures, then cell assemblies coding for the different figures should be expected to be activated in alteration (Marlsburg et al., 1978, 1986; Singer, 1990).5 Later, a research team headed by Singer found that neurons in the visual cortex of cat, when responding to stimuli conforming to the same figure, exhibit oscillatory responses and appear to fire in synchronization across even distantly located functional columns.6
Neurocomputational nets and classifiers facing visual ambiguity
Visual ambiguity in the form of the famous cube presented by L. A. Necker (Fig. 13.1 (i)) in 1832 has been subject to much discussion and many attempts in terms of connectionist modelling and neurocomputation in terms of parallel distributed processing. Rummelhart and Zipser (163-164) review the type of multi-layered architecture of the competitive learning mechanisms usually developed and used in parallel distributed processing approaches:
- The units in a given layer are broken into non-overlapping clusters. Each unit within a cluster inhibits every other unit within the cluster. The clusters are winner-take-all, such that the unit receiving the largest input achieves its maximum value, while all the other units in the cluster are pushed to their minimum value (Grossberg)
- Units may be active or inactive
- A unit learns if and only if it wins the competition with other units in its cluster. A unit learns by shifting its weights from it inactive to its active input lines etc.
In his computational approach to perception Marr suggests the Necker cube invites a neural network with two distinct stable states. This is returned to by Feldman (1985:87;92) in the context of connectionist models and by Rummelhart, Smolensky, McClelland and Hinton (1986) in their parallel distributed processing (PDP) approach. They7 report from runs of a simulation of Necker cube processing by a connectionist network model in terms of the two perspectives with the cube front facing left or the cube front facing right. They show that the system will (almost always) end up in a situation in which all the units in one subnetwork are fully activated and none of the units in the other subnet are activated. That is, the system settles in the stable state (or fixed point) of interpreting the Necker cube as either facing left or facing right. This occurs when the input values are low relative to the strength of the constraints among units, and appears to be functional as long as somebody knows that there is only one right interpretation, and which one it is.
Under high input condition, the system occasionally yield the interpretation that the cube has two front faces. While this has the merit of retaining both the left and the right hand perspective in operation, it makes for an "impossible" interpretation through fusing the two.
Necker's diagram invites two incompatible cube-in-depth perspectives on the basis of the same two dimensional source: one with the cube front facing left when seen from above; the other with the front facing right when seen from below. Rubin's vase permits figure-ground reversal between the image of a vase and two silhouetted faces. And, finally, the well known figure, used by Wittgenstein and others, permits reversal between seeing a picture of a duck and of a rabbit. While such perceptual reversal is difficult to accomplish with regard to the cumbersome Necker cube forms, it is relatively easy to perform upon Rubin's vase, and easy on the duck-rabbit figure. Our perceiving Rubin's vase presupposes the ability to segregate the visual forms into a coherent figure against a coherent ground.
This has inspired some neurocomputational and computer simulation explorations (Bråten and Espelid, 1989; Ekornæsvåg, 1991).8
The basic idea is simply this. Define a perspective P simply as a related set of viewpoints, p1,p2,...,pn, which evoke companion viewpoints, q1,q2,...,qn, as members of a complementary set Q. Let these complementary preferences in viewing the world be imposed by the systems designer or "trainer". Train competing networks, or a population of classifiers, to operate according to different viewpoints, for example, a perspective P that makes one see the world only in terms of faces, and a complementary or rival perspective, Q, that makes another see the world only as composed of vases or goblets. Permit these P- and Q-nets, or populations of P- and Q-classifiers, to operate concurrently, each from their own perspective, when facing visual ambiguity. Then, when faced with Rubin's vase, P will recognize the silhouetted faces, while Q will see the vase. Allow these particular P- and Q-viewpoints to enter into conversation. This will allow the two views to complement each other, or one of them to win, given other clues that comes from other sources, perturbing or supporting the viewpoints in question.
In one of these projects a modified versions of the Neocognitron model developed by Fukushima (1986) has been modified and trained, respectively, as P- and Q-networks. Fukushima's model is a cybernetic self-organizational multi-layered network model, developed for visual pattern recognition, with backward paths and capable of selective feature attention. It is capable of recognizing different handwritten versions of characters and digits, and can also handle certain types of ambiguity. For example, when trained to recognize the individual patterns in this set (0, 1, 2, 3, 4) it will attend and recognize selectively three distinct patterns in this order (4, 2, 1) in the below stimulus (Fig.13.2 (i):
This is relevant for the kind of visual ambiguity exhibited by technical document patterns for which the immediate neighboring context.9
T /-\ E C /-\ T
Figure z. Selfridge's example of instant disambiguation by virtue of available context provides no clues for correct interpretation by conventional automated means. For example, the above label (Fig. 13.2 (i)) may be read as 125, as IZS, as 12 S, as IZ 5, as I 25, etc.
When a single Neocognitron network version, trained to "recognize" both digits and characters, was exposed to the above series, it failed, as expected, in our trials to come out with significant results. When, however, one network was trained as a P-net to "recognize" digital forms, and another was trained as a Q-net to "recognize" letter forms, each came out with clear forms according to their respective "perspectives" when exposed to the partly deformed patterns of Fig.13.3 (ii), and even to highly distorted forms.10 That is, the P-net generated forms conforming to the digits (1 2 5), and the other forms conforming to the letters (I Z S).
Thus, while a single implemented network11 But there is also another possibility. The modified neocognitron which we use as competing P- and Q-nets is one of the most advanced of the about 50 different types of neural network models currently being used around the world in research and applications. Compared to other fairly successful models, such as the Hopfield and the Kohonen networks, and the Bolztman machine, used in the retrieval of images from fragments and pattern recognition, the Neocognitron is a sophisticated network able to identify complex patterns. But its weakness is its requiring large numbers of processing units (PEs) and connections. (Cf. Philip Trevleaven, 1989). appear to defy "training to recognize" patterns of similar form that conform to elements of both the above series,12 the trained P- and Q-nets appeared capable of "recognizing" even highly distorted forms as conforming to viewpoints in terms of their respective perspectives.13
Figure 27 Examples of distorted patterns that are recognized by the P- net and by the Q-net as, respectively, conforming to the form Z and 2.
Their structures are indicated in Fig. 13.3.
So-called back-propagation, or regulatory feedback based on some externally set criteria, works within the limited perspective that each net has been "trained" for, but not accross the networks. Conversation in view of global or more distant contextual information from the past may be required for resolving their difference,14 for example, in the case of exposure to the series in Fig.13.2 (ii), about how labels in this document tend to adhere to the rule (character, character, digit).15
- P-networks, trained and committed to processing viewpoints belonging to a P-perspective;
- Q-networks, trained and committed to processing viewpoints belonging to a Q-perspective;
- N-networks, trained to recognize various patterns for which conversation with a rival perspective is not called for, and hence, without commitment to the P- and Q-perspectives evoked by other networks in the system; and
- P- and Q-network communication points where P vs. Q conflicts are resolved (for the time being) on the basis of conversation between rival networks through access to contextual and rules-based clues provided by an updated global base (or as presently, provided by the trainer).
We term this the DIAD structure (for Dialogic Interpretation of Ambiguous Data). Should later a different solution be required, there may be reversal to the discarded alternatives by virtue of the parallel net.
-> R(P,Q) CONVERSATION ->
in view of past or global information
Figure 13.3 Illustrations of the structure of two implemented versions of the Neocognitron model, a P-net and a Q-net, the first trained to see the world in digit forms, the other in letter forms. When exposed to the same source, each comes out with a form conforming to their respective "viewpoint".
This R(P,Q) philosophy has been explored in a somewhat different version in computer simulations of robots operating in a Necker cube environment. In robot vision various paradigms have been tried out with limited degrees of success (Cf.Aliomonos and Rosenfeld, 1991). Recently it has been suggested that simple and primitive special purpose systems may be preferable.16 A candidate paradigm for robot vision has been offered by the Classifier system, developed by Holland and coworkers (19??).17 It shares the parallel and distributed processing characteristics with connectionist models, while being rules-based in the tradition of production-oriented knowledge-based systems. Classifier principles provide the basic operating characteristics of simulational robots implemented in ADA by Ekornåsvåg (1991). She studies errors in vision and locomotion of computer simulational robots in relation to a Necker-cube.18 The cube has to be touched in order for the simulated robot to resolve which of the two perspectives, P (facing the left) or Q (facing the right), that applies. In terms of error frequencies the simulated robot version operating most closely to the classifier principles appears to do better than one in which for any one single classifier in a P-population there is a complementary classifier as a member of a Q-population. But both simulated robots are capable of evoking complementary P- and Q-perspectives. They appear to cope with the ambiguous environment, changing their dominant viewpoints and adjusting their locomotion accordingly.
While the above Neocognitron and robot simulations concern a referent domain of relevance to the present thesis, they serve no corroborational purposes. They merely serve to demonstrate that it is possible to implement simple network and classifier structures that are capable of evoking complementary viewpoints. A variety of structures allowing for this could have been implemented.
Of relevance to the present thesis is the phenomenon of human perceptual reversal in itself. The fact that a human perceiver is able to, when "setting one's mind to it", to alternate between two such complementary viewpoints suggests that she is able to house complementary viewpoints in parallel or near-parallel. The kind of perceptual alternating invited by figures (ii) and (iii) in Fig. 13.1 appears to presuppose a structure capable of embodying complementary perspectives in concurrent or near-concurrent operation and which may alternate as a consequence of the mind setting. Such alternating may be considered an extreme case of complementary viewpoints in dialogue. Thus, structural prerequisites for perceptual reversals may relate to a structural prerequisite for the mind's inner dialogue with itself, that is, with the complementary perspective of the virtual other.
While perception is mostly considered in terms of mediating representations, Gibson and Heider, each from different points of departure, invite considerations in terms of ecological or direct perception of the world and others in it. In human perception, Heider, like Tomkins and Whitehead, stress affects or feelings as basic in perception. William James, a forerunner of network modeling, points to affective interest as basic to the operation of associative networks. But then, this also entails dissociation, that is, between networks based on complementary or rival affective interests.
In this vein the concept of perspective may be defined in terms of feeling, as a family of viewpoints involving graded feelings that include and generate a world and its complement as felt on the basis of affective interests. In chapter 6 a participant perspective, P, was defined as a related set of unsatisfied viewpoints, (p1, p2, ...,pn) which by virtue of gradation of feelings distinguish that which is to be included by the perspective, and which invite viewpoints belonging to a companion perspective, Q, so that the graded feelings of self-satisfaction in P and Q feed upon the complementary relation to each other.19 This aspect of feelings as affective interests involved in the conversation between complementary perspectives, escapes the above crude "neurocomputational" and simulation explorations.20
But the structures capable of realizing such perspectives in concurrent operations in a human perceiver - one view dominant and holding the foreground, the other receding and maintaining the background - may be relevant to the everyday phenomenon of divided attention.
Divided attention and consciousness
In specifying dialogic closure in Part One I have avoided the term "consciousness" which easily evokes reference to processes of mediation and reflection, in contrast to phenomena of felt immediacy involved in dialogic closure. In the affect attunement that may accompany protoconversation between infant and caregiver perception of the actual other, or what Trevarthen terms alteroception, appears to be immediate and direct, not indirect, mediated by representations. The self-organizing dyad realizes itself through the interlaced networks involving the bodies and neurophysiological structures of the two participants in direct or immediate reciprocal operations. Mediation in terms of the re-presented past other comes in at the moment the affect attunement is broken. But this does not entail that feelings are absent from the way in which the child gazes at the mother in wonder. She is included in the child's perspective in another manner than during the affect attunement, but still in a way that involves feeling.
Take for example the toddler engaged in playing with his toy, with his back to the mother who accompanies his playing with noises in attunement with his excitement. The toddler is devoting his attention to the plaything, included in his perspective. But this does not entail that the mother escapes his attention. She remains present in the background, included in his companion perspective. The moment she comes out of tune or is interrupted by something, the toddler stops his playing and turn to look at her, pulling her into what is now his foreground perspective.
Reflective awareness, for example of the feeling of affect attunement between mother and child, emerge only at the moment when affect attunement breaks down. Then the child stops his activity and gaze questioningly at the mother (Cf. Daniel Stern, 1985: 150). There is acute awareness of something lost in the past, bringing about an inquiry about why things have changed. During the affect attunement the mother was present to the child, included in his companion space even when his main attention was directed elsewhere. While still in the same physical room, she is no longer with the child in this immediate sense when the attunement has been broken, even though the child now devotes all his attention to her.
The illusory unity of consciousness?
Independent of each other, Ulrik Neisser (1976) and Ernest Hilgard (1977) have considered anew everyday assumptions and experimental evidences on divided or dual attention.
Experiments in the 1950s on selective listening to concurrently presented messages showed the subjects to almost entirely ignore the secondary message, but not quite. On closer inspection that more was picked up from the unattended voice than previously assumed. Already at the turn of the century experiments on attending two things at once were carried out. Neisser concludes from his review that it seems clear the amount of information picked up from one source while attending to another is not limited by any fixed mechanism, but appears to depend on skill. Practiced subjects can successfully carry out divided attention which the novice cannot.21 Neisser models perceptual processes in terms of perceptual cycles involving anticipatory schemata which are plans for explorative activity as well as readiness for particular kinds of optical structures. Some are innate, operating outside of attention, while ready to detect their proper signals no matter what other perceptual cycles of attention may be in progress. Thus, permitting the concurrent operation of perceptual cycles, some more autonomatic than others, Neisser can account for phenomena of dual listening and doings. As for consciousness, he makes this declaration:
"It is often said that a person can only be conscious of one thing at a time.........Introspection does not necessarily show that one is aware of only a single thing at a time. I think that people report the singleness of consciousness largely because the philosophical assumptions of our culture require it.."(Neisser, 1976, p.104).22
Hilgard declares that the unity of consciousness is illusory. We may pay acute attention to something in the present while being aware of several things at the same time. Even divided attention is familiar in everyday life. For example, in the process of a conversation, while paying attention to the what the other is saying, the listener may at the same time be preparing his reply. While replying he may be watching the other for confirmation of his being understood, and perhaps changing the direction that his reply is taking him as a consequence of the expression in the other's face. Sometimes, for example, while driving a car and talking to the passenger the car driver may devote most of his attention to the conversational topic until some traffic incident calls upon his attention. When there is no awareness at all of the parallel process of thought or movements the latter is said to be dissociated from the conscious awareness of the person.
Explaining "the hidden observer"
In the late 50s Hilgard put into operation a research laboratory on hypnosis experiments, re-examining the assumptions in dissociation theory. The breakthrough occurred when a double train of thought in a subject unexpectedly was revealed in a classroom demonstration on hypnotic inducement of deafness.
Hilgard (1977, 1986) reports from a series of experiments in which the subject's senses of hearing and of feeling physical pain, partly or wholly is being set aside through hypnosis. The first disclosure of what he came to term a "hidden observer" occurred in this way: Using an experienced subject who was blind, Hilgard induced deafness, telling him that he would be able to hear when a hand was put on his shoulder. The class was shown how unresponsive the subject under hypnosis was to noise or speech. Then someone in the class asked whether the subject really was as unresponsive as he seemed.
Hilgard then addressed the hypnotically deaf subject in a quiet voice, mentioning that there perhaps is some part of the subject that might hear his voice. "If there is," Hilgard continued, "I should like the index finger of your right hand to rise as a sign that this is the case". To the surprise of the class, and the instructor, the finger rose. When the subject was asked what he remembered, he mentioned that everything had become still, he had got bored and started thinking about statistics. Then he felt his forefinger rise. He wanted to know why. Before telling him, Hilgard asked for a report from "that part of you that listened to me before and made your finger rise".
A detailed report was given by the hidden other, which Hilgard metaphorically terms the "hidden observer", and which later has been found to recur in other hypnosis experiments on suggestions on pain, as well as hearing.23 These phenomena, and the phenomenon of divided attention, are taken as an indication of consciousness as being divided, described in terms of dissociation and a double train of thought in the mind of the individual.
Disscussion and explanation in terms of the present thesis
Although such "hidden-observer" experiments have been replicated in several laboratories and clinics one may ask whether the reported occurrences reflect some underlying phenomenon or are merely the outcome of experimental constructions. An obvious ground for critique is to attribute to the subject a wish to comply with the experimenter's request and to simulate being hypnotized. This has been tested out by Spanos and Hewitt (1980). They asked subjects of proven low hypnotizability to simulate hypnosis, and compared their behavior to higly responsive subjects. Naturally, the simulators could report on the process, as if they harboured a hidden observer. Their reports, however, have been judged by Hilaard and associates to differ significantly from the reports provided by the "hidden observers" of actually hypnotized.24
An important but unresolved problem in the neodissociation theory that have emerged from these experiments, concerns the question why some highly responsive subjects do not appear to have access to a hidden observer:
"A finding not yet satisfactorily explained is that among highly responsive hypnotic subjects, that is, those who can reduce both pain and hearing substantially when appropriate suggestions are given, only half have access to covert pain or hearing by the hidden observer technique."(Hilgard, 1986: 195)25
The above finding, as well as the original case, can be explained in terms of the virtual other. For those subjects who come up with a "hidden-observer" report, the hypnotist may be seen to control the subject's self, but not the subject's virtual other. For the subjects who are without any concurrent "hidden observer" during the hypnosis, the hypnotist may be seen to have replaced the virtual other, filling the subject's companion space and excerting his control from there, much in the same way in which the adult may fill the infant's companion space and replace the virtual other, but without the dialogic closure.
Let B denote the subject's self and *A the subject's virtual other, functioning as the hidden observer in some of the subjects. Let A denote the hypnotist as the subject's actual other in the experiment, and <B> the hypnotic control of B by A. In line with the concepts and notation introduced in chapter 3, the different hypnotic transforms may be succinctly indicated as follows:
(3) For a subject with a hidden observer: B,*A := <B>,*A
(4) For a subject without a hidden observer: B,*A := <B>,A
The state indicators to the left of the sign := indicate the original dyadic constitution of both kinds of subjects. To the right of the sign (for becoming) the different outcomes are indicated. In the case of (3) B, but not *A, is monitored by A. In the case of (4) B is monitored by A, who is also replacing *A. That is, in both cases the subject's self B is monitored by the hypnotist A, but in the latter case (4) the hypnotist excerts his control from the subjects companion space, replacing the subject's virtual other *A. Since this actual controlling other has replaced the subject's virtual other in case (4), there is no participant virtual other to "observe" or "report" anything.
For the other subjects (3), whose selves are also passivated or "put into brackets" by the experimenter, the virtual other remains unmonitored by the hypnosis, and hence continues to operate. But the experimenter creates a barrier to the mind's internal dialogue, takes control over the self perspective, while the virtual other remains as a hidden observer of the events, without means to enter into conversation with the passivated self-perspective. In contrast, for the highly responsive subjects (case 4) in whom no hidden observer continues to operate, the experimenter has filled the companion space, replacing the virtual other as a controlling actual other.
It is consistent with such an explanation that highly responsive subjects unable to come up with a hidden-observer report are reported to be more compliant to suggestions to regress to feel like children again:
"Subjects without a hidden observer are more "complient" to age-regression suggestions - that is, they report feeling like children again - whereas those with a hidden observer inevitably report a persistent duality of awareness. During age regression they see themselves simultaneously as adult observers and as children."(Atkinson, Atkinson and Hilgard, 1983: 185)26
This duality appears to be spontaneous, not suggested by the hypnotist. Again, this fits with the above account. For those who report such a duality, the hypnotist while calling upon the child self, has not replaced the virtual other who remains in an observer's position. They conform to (3). For those that do not report any duality, the hypnotist has replaced the subject's virtual other, conforming to (4). The latter suggests a sequence whereby the subject submits to the complementary perspective imposed by the dominant actual other, filling the companion space of the subject's virtual other. Apparently, the persons in whom there is no "hidden observer" to report anything of the hypnotic event have admitted the controlling agency to fill the companion space of the subject's virtual other. This may be compared to the way in which the infant's companion space can be filled by the actual adult other in a direct mode of relationship.
Does a dual brain entail a double mind?
A few years after Hilgard's laboratory for experimental explorations of assumptions from the last century about divided consciousness had been put in operation, another decisive event occured that was to reactivate the issue of a single or double mind. This was Sperry's publication of his findings in 1961.
In her study of the history of ideas on the double brain, Anne Harrington (1987) finds it difficult to uncover any article or essay on the dual brain after 1920 and before this publishing event.27
Already in 1844 Wigan published his work about "The Duality of the Mind". A few years before Hewitt Watson(1836) had asked: "What Is the Use of the Double Brain?". He argued that the two halves could engage in cooperative activity and permit ideas and feelings of others to be apprehended. He even suggested that communication with others may just be "self-communing between the hemispheres of our brain".28 In French neurophysiology and psychiatry at the turn of the century, Binet wrote a book on double consciousness and Pierre Janet viewed alternating consciousness in terms of dissociation. But later, when Janet and Piaget participated in a symposium on individuality in Paris 1931, Janet saw the challenge to explain how a multiplicity of diverse elements could constitute a psychological unity, while Piaget's concern was the formation of reason.29 By then single-minded consciousness, except in pathological cases, appeared no longer to be questioned.
The split-brain studies reactivated the question of whether a dual brain entailed a divided mind. We tend to attribute to consciousness a phenomenological unity that denies a simple identity or one-to-one correspondence with the partial complementarity of the brain hemispheres. Is there a structural basis for a single-minded conscious self, or can the brain, when divided, permit the realization of two co-conscious selves?
Those were the kinds of questions that Roger Sperry (1985) has raised on the basis of his experimental findings from split brain studies. They were reported in Science30 three decades ago. Ten years earlier he had begun with Myers to study cats after section of optic fiber systems and corpus callosum.31 It was followed up by experimental studies on monkeys, and finally on human patients who, for medical reasons, had undergone surgical section of forebrain commissures (commissurotomy). The first patient was a 48-year old war veteran who in 1961 underwent the operation of disconnecting the two halves of the cerebral cortex to prevent seizure activity.32 Split brain patients' response to visual and tactile stimuli presented in each half-field of vision and touch were experimentally studied. For example, presented with an object in the left visual field the patient reports that he cannot see the object (projected to the right hemisphere) while he can find it with his left hand, but not using his right hand.
The two disconnected hemispheres were found to function concurrently, but independently, in parallel when different stimuli were presented simultaneously to the two hands or to the two visual half-fields. That is, things felt with one hand or seen in the corresponding half visual field constituted a world of its own independent of the world of things felt, seen, and processed by the other hemisphere. The two worlds could be grossly incompatible or mutually contradictory without either hemisphere noticing that anything was wrong. Each surgically disconnected hemisphere was revealed to function, to a significant extent, independently of the other. As Sperry (1985) reports, each appeared to "have a mind of its own, but each cut off from, and oblivious to, conscious events in the partner hemisphere". In tests on self-consciousness and levels of social awareness, it turned out that even the right hemisphere, despite language deficits, harbors a well-developed, seemingly normal conscious self with a level of social awareness in close accord with the presurgical character of the patient, and also with the other hemisphere.33
Joseph Bogen, one of the medical doctors who performed the first split brain operation, draws this conclusion from the subsequent studies of the patients: First, it takes only one hemisphere to have a mind. Second, following surgery, the two hemispheres can sustain the activity of two separate spheres of consciousness. The controversial issue is this:
"Does the surgical splitting of the brain create a duality of consciousness or duality of mind?...Or is it an experimental maneuver that makes it possible to demonstrate a duality that was previously present..?"(Bogen, 1985:38)34
Bogen is of the opinion that such a duality is present before the cerebral commissurotomy. Puccetti (1973) argues in the same vein: we do not normally notice our being of two different minds or two different "persons" because when the commissures are intact the two brain hemispheres operate in close synchrony.35
Sperry himself has favored a different view. While each surgically disconnected hemisphere appears to have a mind of its own, he considers the conscious mind to be normally single and unified. It is mediated by brain activity that spans and involves both hemispheres, which function together as a very closely integrated whole. Consciousness is seen to be a holistic or emergent, functional property of high-order brain activity, but with causal potency. With regard to its subjective qualities it involves a system of organizational properties that are select and special to operations at top level of the brain hierarchy and supercedes in brain causation the powers of their neuronal and other infrastructures36:
"Consciousness appears in the causal chain of brain event at higher cognitive levels in the form of irreducible emergent properties of brain activity. Mental events interact on a holistic 'functionalistic' basis at their own cognitive level and also exert a concomitant supervenient form of downward control over lower level brain events." (Sperry and Trevarthen, 1990).37
Sperry (1968, 1985) has elsewhere described the structure of the conscious system to be Y-shaped, that is, divided in its more structured level but undivided with regard to organizational properties.38
In terms of the present thesis
How does the above relate to the thesis of the virtual other partaking in the mind's dialogue with itself? The thesis attributes an inherent duality to the mind involving a self and a virtual other. In this sense it relates to Bogen's point. But the self and the virtual other are seen to mutually complement each other as inter-dependent constituents of a self-organizing whole. In this sense the thesis relates to Sperry's and Trevarthen's point about an irreducible holistic organization. The present thesis presupposes that complementary mental activities can be concurrently realized in the same brain, even when not subjected to commissurotomy. But it does not imply that there normally in the unperturbed brain be realized two separate minds in independent operations as Bogen and Puccetti would have it. It entails that the mind as a self-organizing dyad recreates itself as an operational unity involving interdependent and mutually constituting complementary perspectives as participants in the self-organizing dyad of the mind. As a self-organizing dyad the mind recreates itself as a unity through dialogic closure or communion.
Thus, the present thesis need not be inconsistent with Sperry's emphasis on the unity of the organizational whole, provided this be considered a dialogical unity that presupposes structural prerequisites for the concurrent co-operation of complementary perspectives. Such a structural prerequisite may be satisfied by the way in which "the two hemispheres in the normal intact brain tend regularly to function closely together as a unit" (Sperry, 1985:19).
It may, however, also be satisfied by the way in which two brains can be involved in the realization of dialogic closure, for example, by mother and infant in protodialogue and affect attunement, or by two intimate friends in dialogue or communion. The near-perfect synchronization, co-ordination of gestures and sound, and bodily "postural echo" sometimes exhibited by such dyads demonstrate how two participants, while complementing each other, can function closely together as a unity.
In a film shot at 48 frames per second, for example, one may see how sudden, small mutually matching movements start on the same frame of film, as if the participants were of one body, not two.39 Also infant-adult interplay may sometimes exhibit a near-perfect synchrony, albeit the more typical pattern is the mutual completion of gestures, with clear indications of bodily attunement.
According to the thesis brought forth in this book this comes about without any operational jump when each, as an actual other, replaces the virtual other. The virtual other is not postulated as a structural entity, entailing a specific brain location, but as an organizational and operational complementary participant perspective that partakes in the self-organizing mind which recreates itself as a unity through dialogic closure. But the thesis does imply that the single brain be capable of realizing the mind as a self-organizing dyad that recreates itself as a unity through dialoging with a virtual other, and permits the co-operative and reciprocal involvement of another brain without an operational jump when the actual other replaces the virtual other in dialogic closure. In such dialogic closure there is an immediate feeling of unity, irrespective of whether it arises in communion with an actual other or from the mind's dialoging with itself, that is, with the virtual other.
I shall return to the above example of what Morris terms "postural echo" in the concluding chapter to follow, concerned with the issue of time.
131191 NOTES TO CHAPTER 13
1G.N.A. Vesey (ed.): Body and Mind. Readings in Philosophy. George Allen and Unwin, London, 1964, p.47. Cited in : A. Harrington: Medicine, Mind, and the Double Brain, Princeton University press, Princeton 1987, p.6.
2W. S. McCulloch: "Recollections of the many sources of cybernetics", ASC FORUM, VI, No.2, 1974.
3G.N.A. Vesey (ed.): Body and Mind. Readings in Philosophy. George Allen and Unwin, London, 1964, p.47. Cited in : A. Harrington: Medicine, Mind, and the Double Brain, Princeton University press, Princeton 1987, p.6.
4Torsten N. Wiesel: Development of the visual cortex. In: K. B Hell, O.D. Lærum and H. Ursin (eds.): The Nansen symposium on new concepts in neuroscience, Sigma, Bergen 1987, pp.59-60.
5C. von der Marlsburg and W. Schneider, Biol. Cybern. 28, 223, 1978; C. von der Marlsburg and E. Bienenstock, Europhys. Lett., 3, 1243, 1986, referred in: W. Singer: Search for coherence: A basic principle of cortical self-organization, Concepts in Neuroscience, vol. 1, no.2, 1-26, 1190.
6C.M. Gray, P. Konig, A.K. Engel, W.Singer: Oscillatory responses in cat visual cortex exhibit inter-columnar synchronization which reflects global stimulus properties. Nature 338, 334, 1989. See also Science, 249, Aug.24 1990, pp.856-858.
7D.E.Rumelhart, P.Smolesnky, J.McClelland & G.Hinton in: J.L.McClelland and D.E.Rumelhart (1986),vol.II,pp.11-17.
8Stein Bråten and Rune Espelid: ............. We wish to thank Kunihiko Fukushima for providing updated papers on his Neocognitron model, which is the basis for the adapted P- and Q-networks used in the simulations; and Fredrik Manne for assisting in the computer simulations (on IBM 3090/200 VF at BSC) on the basis of C-versions implemented by him and Petter Möller. Affiliated institutions are acknowledged for project support, especially BSC IBM, and Dept. of Cognitive Psychology, Bergen, during the period (1987-89) in which the first-listed author was guest professor in cognitive science at the University of Bergen and consulting scientist at BSC. We also wish to thank ............
9Normally, one use the context to disambiguate, for example when the same distinct pattern, such as this /-æ, in one instant may be seen as "H" and in the next instant may be seen as "A" (Fig. z).
10With the respective strength values 2.41; 2.58; 2.73 for the p-net, and 2.51; 3.59; 0.12 for the q-net.
11The competing networks have been implemented in C. Since a crucial feature is the conversation between competing networks, object-oriented languages have been considered for implementation of the DIAD structure: Ada, Simula, and C+.
12In the first implementational stages, two different adapted versions of the Neocognitron model have been implemented in C and run on IBM 3090/200VF and on an IBM 6150(RT/PC). Trained to recognize nine clearly distinguishable patterns conforming to the elements in this series, (0,1,2,..9), they are capable of recognizing partly deformed input patterns in the Gestalt of the respective numbers, and even to extract superposed forms. However, when confronted with ambiguous stimulus that may permit recognition both as characters and numbers, we were unable to train a particular network to recognize characters and numbers in such a manner, even when a variety of inhibition values were tried out, that it could recognize a character pattern and a number pattern in the same distorted stimulus.
13In Figure x, three such increasingly distorted forms turn out to be recognized by each of the nets with these respective strength values.................
14Such a conversational structure has not yet been implemented. Ronald Chrisley (of Oxford and Xerox PARC) has mentioned that at Oxford they explore competition between perspectives in terms of 'cognitive maps'. He has put the question to us about whether these competing P- and Q-nets have to be physically different from each other: Isn't it sufficient for them to be conceptually different only? Initially we thought so. But we are no longer sure, when being trained to recognize the world in terms of different perspectives, they do become structurally different from each other. In any case, they put heavy demands on a complex program environment that permits an exceedingly high number of processing units (PEs) and interconnections, in addition to the demand for an environment that permits their inter-communication, when offering their rival interpretations.
15The complete structure comprises ideally:
16Y. Aloimonos and A. Rosenfeld: Computer Vision. Science, 253, Sept 13 1991 1249-1254. R.A. Brooks: A new approach to robotics, Science, ibid., 1227-1232.
17J.H.Holland, K.J.Holyak, R.E.Nisbett & P.R.Thagard (1986).
18Anne-Grethe Ekornåsvåg: Simulation in a Necker Cube Environment. Student thesis in informatics. University of Bergen, Dept. of Informatics, Bergen 1991. The model has been implemented in Ada.
19This definition is introduced in S. Bråten, ...1988..with reference to Whitehead and others...
20In cognitive science and computer simulation approaches, there are several early attempts to include aspects of 'hot cognition' and feelings in simulation models, for example, by Robert Abelson (196?; 197?), Stein Bråten (1968), Kenneth Mark Colby (198?); Roger Schank (19..); and quite recently, Phil Johson-Laird (198?).....
21U. Neisser, op.cit., p.92.
22U. Neisser, ibid, p. 104.
23Ernest Hilgard: Divided Consciousness. John Wiley, New York 1986, p.186.
24R.L.Atkinson, R.C.Atkinson and E.R.Hilgard: Introduction to Psychology, Harcourt Brace, San Diego 1983, p.185. Cf. also D.O Hebb: 'Understanding Psychological Man: A state-of-the-science report' Psychology Today 16, pp.52-53, and N.P.Spanos and E.C. Hewitt (1980): The hidden observer in hypnotic alagesia: Discovery or experimental creation? Journal of Personality and Social Psychology, 39:1201-14 (1980).
25E. Hilgard, op.cit., p.195.
26Atkinson, Atkinson and Hilgard, op.cit., p. 185, referring to J.R. Laurence (1980): Duality and Dissociation in Hypnosis. Unpublised MA thesis, concordia University, Montreal 1985.
27Anne Harrington: Medicine, Mind, and the Double Brain., Princeton University Press, Princeton, New Jersey 1987, p.248.
28Harrington, op.cit., quotes Watson (1936:610) stating: mental communication with others, as it is commonly expressed, may just be self-communing between the hemispheres of our own brains, accompanied by signs and sounds addressed to the senses."
29P. Janet: L'individualite' en psychologie; J. Piaget: l'individu et la formation de la raison. In: L'individualite', Libraire Felix Alcan, Paris 1933, pp.39-50;67-116.
30R.W. Sperry: Cerebral organization and behavior. Science, 1961, 133: 1749-1757.
31R.E. Myers and R.W. Sperry: Intercular transfer of visual form discrimination habit in cats after section of the optic chiasma and corpus callosum. Anat. Rec., 1953, 115: 351-352.
32M. S. Gazzaniga: The split brain in man. Scientific American, vol. 217, no.2 1967 pp.24-29
33R. W. Sperry: Consciousness, identity, and divided brain. In: D.F. Benson and E. Zaidel (eds.): The Dual Brain, The Guilford Press, New York 1985, pp.11-26.
34J. E. Bogen: The Dual Brain: Some historical and methodological aspects. In: D. F. Benson and E. Zaidel (eds.): The Dual Brain, The Guilford Press, New York 1985, pp.27-43.
35R. Puccetti: Brain bisection and personal identity. Br. J. Philosophy of Science, 24 1973 339-355 (Referred to by R. Sperry (1985) op.cit. p.21.
36R. W. Sperry, op.cit., p.21-24.
37Roger W. Sperry and Colwyn Trevarthen: Turnabout on Consciousness: New paradigm for causation. Conference abstract August 1990 for the ...............Italy....
38R. W. Sperry: Mental unity following surgical disconnection of the cerebral hemispheres. In: The Harvard Lecture Series, Vol. 62, Academic Press, New York, 1968: 293-323. Referred to by Sperry (1985), op.cit., p.22.
39Desmond Morris:..........W.S. Condon and W.D. Ogston: Sound Film Analysis of Normal and Pathological Behavior Patterns, Journal of Mental and nervous Disorders, 143, p.338-347.
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