NEUROPHENOMENOLOGY OF INTENTIONALITY
AND TIME CONSCIOUSNESSThe perceptions of things are primordial experiences in relation to all memories, fancy presentations, and so forth. They are primordial in the sense in which concrete experiences can be that at all. For closer inspection reveals in their concreteness only one, but that always a continuously flowing absolute primordial phase, that of the living now.
Edmund Husserl, Ideas
The brain is waking and with it the mind is returning. It is as if the Milky Way entered upon some cosmic dance. Swiftly the head-mass becomes an enchanted loom where millions of flashing shuttles weave a dissolving pattern, always a meaningful pattern though never an abiding one.
C. Sherrington, Man and His Nature
I have emphasized from the beginning that the essence sine qua non of consciousness as described in both the western and the eastern phenomenological traditions is intentionality: that consciousness is vectored, is always "of something." I wish now to explore this all-important essence in greater detail, for it has much to do with how the mature contemplative comes to self-awareness.
Intentionality is experienced as a distinction between subject and object, between the phenomenon intended and the "I" doing the intending. It is also experienced as: (1) the constellation of cognitive (affective, motor, conceptual, imaginative, categorically intuitive, etc.) and perceptual (primarily intuitive, identification, recognition, etc.) processes upon the object, and (2) as a unity of phenomenal reality that is both comprehensive and meaningful. This subject-object polarity, so apparent to direct experience, was noted in western philosophical tradition as early as the Greeks and most notably by Franz Brentano (1838-1917) in his Psychologie vom empirischen Standpunkt (Brentano 1874). This theme was later elaborated by Husserl in a variety of works, including Cartesian Meditations (1977) and Ideas: General Introduction of Pure Phenomenology (1931). (1) The recorded understanding that consciousness is essentially intentional dates further back in eastern phenomenological traditions. For example, of the seven universal factors of consciousness described in the Buddhist Abhidharma , five factors ( phassa or "initial contact" with the object, manasikara or "turning the mind" to the object, cetana or coordination of mental factors upon the object, sanna or "recognition" of the object, and ekaggata or "one-pointed" concentration upon the object) are explicitly intentional by nature.
What is of significance in the present context is that in both eastern and western traditions, the subject is experienced as arising and dissolving with the object. In Abhidharma , as well as other Buddhist teachings, these universal factors arise as a consequence of contact with the object (see eg. Guenther and Kawamura 1975: 11). In Husserlian phenomenology, both the object ( phainomenon ) and the ego ( cogito ) are simultaneously constituted within the stream of consciousness ( cogitationes ; see Figure 0, and also see Funke in McKenna et al. 1981: 83).
Figure 0. A Schematization of the Simultaneous Arising and Dissolving of the Cogito and the Phainomenon Within the Stream of the Cogitationes.
As we have seen, a significant feature of intentionality is that it normally produces a total ("gestalt") field of experience as it unfolds each and every moment within consciousness. The pre-scientific, mundane and culturally conditioned world of experience (Husserl's 1970 "lifeworld") tends to remain "stuck together" within the sphere of consciousness. And, as we have said, perception operates to differentiate percepts, attentional structure initiates a point of view, and cognition performs associative operations upon percepts -- and all of this from the point of view of an ego, an "I" for whom the world arises. This subject and object distinction is produced as a consequence of the interaction of the polarized processes Husserl (see Chapter Four) called the "noematic" and "noetic" aspects of consciousness. Because this intentional polarity is fundamental to the structure of consciousness, it is thus fundamental to social cognition and the "enculturation" (transmission of "culture" from generation to generation) of members of each and every society on the planet (see Chapter Eleven; see also Schutz and Luckman 1973).
The subject of which we speak is not , of course, the empirical ego, as I took pains to point out in Chapter Two. During the process of maturation, the contemplative has discovered that there are no phenomenological grounds upon which to lodge any belief whatever in the existence of an empirical ego. He or she knows with the complete certainty that comes from direct experience that there exists no discernible ghost in the machine, no homonculus, no seamless, substantial, enduring "wee me." This discovery and inherent intuitive knowledge makes it possible to eliminate the obstacle presented by ego-centered psychologies and to speak of the subjective end of the intentional polarity in a manner more in keeping with what we know about how the brain works.
Realization of the delusory nature of the empirical ego often occurs as a consequence of "transpersonal" experiences; that is, experiences outside the boundaries of the conditioned self-concept. Transpersonal experiences are frequently very important, not only to maturing self-awareness on the part of a contemplative, but also to understanding traditional cosmologies and religious systems. Because the present book is concerned with phenomenology and the contemplative skills requisite to exploring the structures of experience, I have had little to say about transpersonal experiences. But our biogenetic structuralist group have understood the importance of transpersonal experiences to the evolution of human consciousness and the explanation of religious institutions, and have written extensively on this topic (see e.g., d'Aquili 1982, 1983, Laughlin 1989, 1989, Laughlin, McManus and Shearer 1983, Laughlin, McManus and Webber 1984, Laughlin, McManus and d'Aquili 1990, MacDonald, Cove, Laughlin and McManus 1989, Webber, Stephens and Laughlin 1983). Of course, others have discussed the issue as well (see e.g., Wilber 1980, 1983).
It is significant that nowhere in the Buddhist Abhidharma is there the slightest reference to an empirical ego. Buddhist psychology recognizes the "pure ego," or ahamkara -- "that which says 'I'" (Govinda 1974: 54) -- but repudiates the empirical, or psychological ego -- the "hypertrophic 'I'-consciousness" (ibid: 54) -- as merely a biproduct of ignorance, delusion and false-seeing ( avijja ). Nor is it necessary to Husserl's (1970) transcendental phenomenology to ground it upon such an ego. Rather, the operational ego is discovered to be no more than a "standpoint" related to cognitive operations (the "cogito") performed upon the object of consciousness (Husserl 1931: 116ff).
PREFRONTAL CORTEX AND INTENTIONALITY
As I mentioned in Chapter One, the cortical areas most implicated in intentional functions are the dorsolateral and orbital prefrontal cortex (see Pribram 1971, Pribram and Luria 1973, Fuster 1980, Stuss and Benson 1986). Lateral (or "granular") prefrontal cortex has exhibited allometrically greater development than most other areas in hominid evolution (Nauta 1971, Passingham 1973) and is richly and topographically interconnected with the mediodorsal nucleus of the thalamus, the parvocellular portions of which are phylogenetically the most recent thalamic area to develop, and the one that once was the highest association area in the brain. Granular prefrontal cortex is also the last to myelinate during ontogenesis (Jouandet and Gazzaniga 1979), indicating an extraordinarily lengthy period of significant prefrontal development and involvement of those processes in the development of other areas of the nervous system. Orbital prefrontal cortex directly projects to and receives afference from cingulate and other limbic structures mediating affect, and the hippocampus (and indirectly the amygdala), the hypothalamus and brainstem tegmentum, all of which are involved in regulating the neuroendocrine and arousal systems (Fuster 1980: 24ff).
[FIGURE OF BRAIN HERE]
The prefrontal cortex is also profusely interconnected with modal and multimodal sensory association cortex (Adrianov 1978, Geschwind 1965). It is particularly significant that only the prefrontal cortex receives afference from all sensory modes (including olfaction), as well as from multimodal association areas (Stuss and Benson 1986: 24), and that little or none of this afference is from primary sensory cortex (Jones and Powell 1970). This tends to indicate that the prefrontal cortex is an area where all of the abstract perceptual aspects of the sensorium "come together" in unitary awareness.
There are rich interconnections between prefrontal cortex and the association cortices in the inferior parietal lobule (mediating concept formation) and rostral temporal cortex (mediating abstract imagery). These various interconnections are primarily via corticocortical fibers running along the superior longitudinal fasciculus (connecting prefrontal cortex with association areas of temporal, occipital and parietal cortex), the inferior longitudinal fasciculus (connecting the same general areas) and the cingulum (connecting cortex all along the cingulate gyrus, the isthmus and the parahippocampal gyrus. These interconnections mediate the associations intended by the prefrontal cortex upon the object (either as anticipated or as fulfilled in the field of dots).
Prefrontal areas in each hemisphere are directly interconnected with homotopical and heterotopical sites in contralateral prefrontal cortex by reciprocal fibers running across the genu and rostrum of the corpus callosum (Stuss and Benson 1986: 33). These interconnections allow the asymmetrical functions of the two prefrontal cortexes to consolidate into a unitary experience of the object.
In short, prefrontal cortex is involved in a three-way dialogue with other parts of the nervous system: via projective fibers to subcortical structures involved in arousal, orientation and affect (and the whole array of ergotropic-trophotropic functions), via associative fibers to other cortical areas involved in sensory, as well as motor, language, imaginal, and cognitive functions, and via callosal fibers with prefrontal cortex in the other hemisphere. The prefrontal cortex is richly endowed with channels for integrating both its own functions, and those of other areas of the nervous system in service of intending the object.
[FIGURE OF THREE-WAY DIALOGUE HERE]
Our principal concern here is with the corticocortical connections between prefrontal and sensorial areas. Our best view at the moment has sensory information entering cortex at the primary association areas, then to adjacent "secondary" and "tertiary" association areas in the parietal (somatic), occipital (visual), and temporal (auditory) regions, all rather posterior relative to prefrontal cortex (Fuster 1980: 29). Each secondary sensory area sends information not only to the proximal association area(s), but to (and receives from) prefrontal cortex (Roland 1982). Thus, part of the function of the prefrontal lobe is as a multimodal association area, most likely concerned with "egocentric spatial orientation" towards, and integration of information about discrete events in sensorial space (Pohl 1973, Mishkin et al. 1977) -- sensorial space itself being constituted in part by, and motor activity within sensorial space being integrated in part by, association networks in posterior parietal cortex (Mountcastle et al. 1975).
We have elsewhere reviewed the neuroscience evidence in favor of claiming the intentional role of the prefrontal cortex (see Laughlin, McManus and d'Aquili 1990: Chapter Four). Summarizing all of this material for our present purposes, prefrontal cortex in humans seems to be intimately involved in mediating: (1) superordinate control and monitoring of lower order, relatively autonomous functions and systems; (2) anticipatory and attentional functions relative to sensory stimuli already constituted by secondary sensory and multimodal association areas; (3) augmentation of intended sensory and cognitive "objects" and inhibition of competitive objects, sense modalities and cognitive functions; (4) planning, initiating, carrying through and monitoring the effects of complex adaptive behavior; (5) production of and projection of redundancy upon sensorial space; (6) facilitation of memory, but not actually involved in primary sensory memory storage; (7) focusing arousal upon selected objects or goals; (8) construction of temporal plans, and maintenance of temporal continuity in perceptual concentration and behavioral response; (9) integration of the sensory world relative to internal states and motor responses, especially when confronted with novelty in the environment; (10) initiation of and motor control of speech, and comprehension of complex textual material; and (11) control of affect, emotion and mood relative to sensorial events.
In short, the general function of prefrontal cortex is the integration of its own functions, and those of other areas of cortical and subcortical tissue intended upon an object, be that object a sensory form, thought, image, or cognitive function. Intention involves anticipation, selection, focusing attention, entraining appropriate cognitions and actions, and monitoring the affects about and motor responses to events in the environment. The latter function should not be overlooked, for, as I have said, it is evident that much of the motor activity of organisms operates to control what arises in the sensorium -- that organisms behave in the world in such a manner that the sensorial world they desire is experienced (see Powers 1973, Arbib 1972, Richards and von Glasersfeld 1979).
An issue that has not been properly addressed in the literature is the likelihood that intentionality has a major role in development. I suspect that the intentional role of prefrontal cortex in ontogenesis is, as with behavioral systems, a primary one which involves organizing the development of subordinate systems configured upon the object until sufficient neurocognitive growth has occurred, and then relegation of those systems to relative autonomy, or for later re-entrainment for frontal lobe purposive processing and projection of redundancy (see Luria 1973, Stuss and Benson 1986, Pribram and McGuinness 1975). This role in development includes controlling and monitoring the construction of self-concepts and images, and are thus vulnerable to influence by culture. Furthermore, it is precisely this role of developmental arbiter that is utilized in re-entraining subsystems that produces the various reductions requisite to the development of the "phenomenological attitude," or mature contemplation.
The Prefrontosensorial Polarity Principle Again
It is becoming obvious that the role of the prefrontal cortex is not only one of implementing "executive" programs when events in the environment become too complex for lower order networks (Pribram in Pribram and Luria 1973: 306ff), but is one involving nothing less than the mediation of the Husserlian "pure ego" in its relations with the phenomenal world as constructed by the sensorium within the conscious network entrained between the two. Distilling the intentional functions of the prefrontal lobes even further, the principal characteristics of prefrontal activity are: (1) the anticipation of (Teuber in Warren and Akert 1964, Pribram 1971), selection of, orientation towards, concentration upon, cognitive operations upon, and motoric activity relative to the phenomenal object abstracted from its sensorial context (Norman and Shallice 1986); (2) the inhibition of irrelevant sensorial objects and events, as well as affective and other neural activities competitive with the object of the intentional process (Fuster 1980); and (3) the establishment of a point of view relative to sensorial events, and under certain conditions of a cognized distinction between self and other, or subject and object (Nauta 1973).
Numbers one and two above involve on the one hand production of abstracted, stabilized patterns of redundancy characteristic of the cognized environment. This redundancy is produced by the various association cortices under the direction of prefrontal processes and is imposed upon the production of ordered, but novel events by the sensorium (Pribram and McGuinness 1975, Pribram 1981, Tucker and Williamson 1984). The emphasis in this function is upon re -cognition on the basis of patterns of "meaning" stored in memory.
With respect to number three, I have suggested in Chapter Three that the sense of distinction between subject and object may be lost under two conditions. It may be lost when prefrontal involvement in conscious network drops below a minimal threshold of intensity so that its intentional functions are laying relatively dormant (hypointentionality), and at the other extreme when involvement of concentration of intentional processes rises above a dualistically maximum threshold of intensity (hyperintentionality). The latter condition may produce the range of absorption experiences ( jhanas or samadhi ) we discussed in Chapter 5.
The prefrontosensorial polarity principle involves a field of meaningful and continuously novel world of experience on the one hand and the wilful, redundancy producing, knowledge organized by prefrontal and associational cortex and constellated upon objects on the other hand (see Teuber 1964, 1972, Pribram 1971, 1976, 1981). Once again, it would be a gross error to imagine this polarity simplistically as a prefrontal homonculus passively watching a sensorial movie. Rather, the phenomenal world as experienced is an active coproduction of entrained prefrontal, associative, motor, sensorial and other processes distributed over wide areas of both cortical and subcortical tissues. There is good evidence (Fuster 1980) that prefrontal intentional processes single-out objects by actively augmenting and arousing the sensorial network mediating the object (or the entire sensory mode) of interest, and just as actively inhibiting alternative objects (and competing sensory modes). The prefrontal system acts like an orchestra conductor who commands the string section to play louder and the brass section to play more quietly.
I am speaking here of but one of a number of principles of organization that may be operating simultaneously in the organization of the conscious network and the mediation of experience. When prefrontal intentional processes are operating relative to environmentally stimulated sensorial processes, we should expect to find a creodic pattern of entrainment distributed between primary sensory cortex and prefrontal cortex. The pattern of entrainment may incorporate such widely dispersed systems as feature-processing networks in secondary and tertiary sensory cortex, recognition processes in hippocampal nuclei, selective arousal by brain stem reticular activating systems, multimodal spatial integration processes in parietal association cortex, motor processes in motor cortex, premotor cortex and cerebellar cortex, and so on.
On the sensorial side the impetus will be towards the portrayal of a topographically veridical model of reality, on the prefrontal side the impetus will be towards generating a feedforward anticipation of, orientation towards, and organization of cognitive processes about sensorial objects and events. The sensorial processes constitute the world, the prefrontal processes constitute the subject rising to anticipate, meet, and cope with the world-object in intentional focus within its sensorial context. In the field between these impetuses is produced the moment-by-moment re-entrainments that are the momentary resolutions of the tension, and that contribute to the ontogenetic development of creodic structures mediating experience over a lifetime.
Also within this field the uniquely human self-awareness and self-reflection may arise -- as it were, the mirror of the brain's own self-knowledge. The total pattern of neural entrainment arising in the moment-by-moment, polar dialogue between prefrontal and sensorial processes is the conscious network mediating consciousness. Self-awareness may be relatively naive (awareness limited to self-concepts, self-images and habit patterns) or relatively enlightened (awareness of the principles and essences of self-construction, and of the watcher, or "pure ego"). The exact role of prefrontal cortex in self-awareness will depend upon how "pure" or conceptually-imaginally loaded are the operations of awareness.
DOTS, PERCEPTUAL INTERMITTENCY AND TIME CONSCIOUSNESS
As noted in the last chapter, a significant feature of the appearance of dots is their intermittency. Dots arise, endure a moment and then dissolve. They can no more be wilfully caused to abide longer than their natural cycle than can the florescent dot making-up a television image. They are by nature momentary in duration, and their nature is conditioned by the organization of the neurognostic structure of the cells mediating them.
But, as we have said, dots do not arise and dissolve randomly. Far from it, for it is apparent to the contemplative who takes up the study that fields of dots arise and pass away in unison. Fields of dots are as intermittent in occurrence as are individual dots. The arising and dissolving of a single field of dots may be termed a sensorial epoch . (2) Perceptual epochs arise and dissolve serially much as a run of photographic frames produces a "moving" picture. Perceptual frames pulse or flicker through consciousness, as does awareness of them.
This is an important essence of perceptual phenomenology, for it is not readily available to naive introspection. For example, in his otherwise trenchant interpretation of Husserl's phenomenology of perception and time consciousness, Izchak Miller argues against the thesis of perceptual intermittency. In so doing he makes the revealing statement:
The evidence [for intermittency] is supposed to be reflective observation, provided that we concentrate hard enough. I must confess that my reflection did not reveal the "coming into being" of my stream of consciousness of a long sound of a constant pitch to proceed seriation like the tick-tocks of a clock, and I do not believe that my failure merely reflects the shortcoming of my power of concentration .
(1984: 167-168, emphasis added)
On the contrary, I suspect Miller's failure to detect the pulsing intermittency of his own perception precisely reflects the level of concentration he was able to apply to the problem. It is one thing to critically philosophize about time consciousness, it is quite another to perform the reduction requisite to the direct intuition of perceptual dots and temporal intermittency. Consider this: Why do serious phenomenologies insist upon training contemplatives to perform reductions at all if every essence is immediately available to casual introspection? Perceptual intermittency is generally not apprehended until perception of form (i.e., "car," "sound of constant pitch," "taste of sole almandine," "inhalation and exhalation") has been reduced so that concentration is solely upon the essential (hyletic) ingredients of perceptual acts.
The Real Now
When the contemplative becomes aware of perceptual epochs and can apprehend the arising and dissolving of them as they occur, then he may be said to have performed the reduction to the "real now." It is well known in phenomenological circles (e.g., Hayward 1984:29-31 and Contril's 1960 edition of Adelbert Ames' writings) that the roots of time consciousness for mundane awareness is in the consolidation of past, present and future operations (see Figure 0).
Figure 0. The Husserlian and Buddhist Notions of the Construction of Time Consciousness. "Now" Under the Natural Attitude Combines Past Retentions, Future Protentions with the Real Now of the Unfolding Sensorial Field.
Ricoeur (1984) notes that this view was a cornerstone of Augustine's philosophy of time. Likewise, Husserl (1964: 48ff; see also Landgrebe 1981: 59, Miller 1984: 85) saw the "primal impressional datum" of perception as being a synthesis of recently past acts of perception ("retention"), of the streaming present ("now points") and of the anticipated future ("protention"):
...the continuity of running-off of an enduring Object is a continuum whose phases are the continua of the modes of running-off of the different temporal points of the duration of the Object. ...Since a new now is always presenting itself, each now is changed into a past, and thus the entire continuity of the running-off of the pasts of the preceding points moves uniformly "downward" into the depths of the past. ...Every primordially constitutive process is animated by protentions which voidly constitute and intercept what is coming, as such, in order to bring it to fulfillment.
(Husserl 1964: 49-50, 76)
The relations among memories of recently past epochs, the "now" or current epoch, and anticipated soon-to-arise epochs are, as Husserl (ibid: 81) noted, "primordial" -- that is, fundamental to the neurognostic organization mediating perceptual acts. Cognitions entrain with the sensorial structures mediating the fields of dots to produce enduring objects and the continuity of events.
Buddhist phenomenology is consonant with the Husserlian view. Contemplatives come to see the real present (the "thought-moment," cittakkhana , or "momentary present," kanapaccuppanna ) as opposed to the "now" of mundane perception (the "serial now," or santatipaccuppanna ) that is actually the continuous concatination of retention ("past," or atita ), real present and protention ("future," or anagata ).
The "serial now," permeated as it is with the "natural attitude," is a prefrontally integrated, cognitive binding of perceptual epochs with memory and anticipation -- imprecisely stated, past, present and future (see Husserl 1964: 62). Perception is experienced to naive introspection as temporally continuous, but epochal by the mature contemplative who has performed the requisite reduction. The experience of sensorial events by the contemplative becomes one of awareness of perpetual beginning and flow. Sensation may even cease to solidify into recognizable objects and is more a stream of epochs of innumerable, momentary particles.
Awareness of the "real now" is common in descriptions of transpersonal experiences, even though the individual may not have carried out a reduction to the level of apperception of dots. A lovely description is contributed by D.E. Harding in his remarkable little book, On Having No Head . It happened to him while he was on a trek through the Himalayas:
What actually happened was something absurdly simple and unspectacular: just for the moment I stopped thinking. Reason and imagination and all mental chatter died down. For once, words really failed me. I forgot my name, my humanness, my thingness, all that could be called me or mine. Past and future dropped away. It was as if I had been born that instant, brand new, mindless, innocent of all memories. There existed only the Now, that present moment and what was clearly given in it.
These sorts of experiences will spontaneously arise in the course of meditation work, such as during the breathing exercise we have explored previously. When concentration upon the sensation of the air flowing in and out of the nostril is sufficiently intense, the meditator comes to lose awareness of inhalations and exhalations as perceptual units. One comes to see that an "inhalation" is actually a cognization that blends retention and protention with the ebb and flow of sensation. That is, the ebb and flow of sensorial dots are interpretable as "inhalation" only so long as the retentive and protentive cognitive activities remain entrained to conscious network. But with enhanced concentration upon the sensation of breathing, the retention-protention entrainments tend to drop away and one remains aware of the "real now" of breathing. Gone, too, are the "gaps" between the inhalations and exhalations. What remains is steadfast concentration upon the coming and going of sensation, a concentration that becomes so intense that all other competing objects and cognitions are ignored and finally drop away. (3)
In Buddhist insight practice, whether the object is the breath, body parts, light, or whathaveyou, the attention becomes single-mindedly fixed upon the dissolving ( bhanga ) aspect of the activity of the field of dots (see Chapter 5). Total concentration upon dissolution ( khanika samadhi ) is the only entrainment that will lead to the direct absorption into and intuition of cessation ( nirodha ) -- that is, the experience of nirvana . According to text (see Narada Maha Thera 1975: 227), the advanced enlightened being may wilfully remain in this absorption into cessation for lengthy periods of time, a facility known as the "attainment of cessation" ( nirodha samapatti ).
Part of temporal dialectic between prefrontal and sensorial structures seems to involve septal-hypocampal centers in the midbrain. Orbitofrontal projections from prefrontal cortex innervate the hypocampus and dorsolateral prefrontal projections enter the lateral septal area (see Gray 1982: 65ff). These areas are also connected to secondary sensory areas and seem to receive sensory information that is already abstracted from the initial processing in primary sensory cortex. In a phenomenological sense, the sensory information arriving at septal-hypocampal sites appear to be "noematic" abstractions from the "primordial filling" of primary sensory cortex, that "filling" already being a rudimentary abstraction of patterned energies in the operational environment.
It was once thought that the hypocampus was a memory storage center. It is now suspected that the septal-hypocampal system does not itself store memories, but is an area that anticipates what will be found in the next sensory epochs and attempts to match what does arise to that which is anticipated from memory constituted elsewhere, perhaps in the temporal lobe. It is, in Husserlian terms, an area (perhaps the area) of the brain specialized to concatenate recent "retention" (abstracted knowledge of recently past epoches), the stream of "now points" (currently arising and dissolving epochs) and near future "protentions" (anticipated sensorial form of future epochs). EEG recordings from sites in both prefrontal cortex and hypocampus indicate significant slow wave negative activity relative to attention to sensory events. Prefrontal theta seems to be associated with concentration upon sensory objects, and slow wave, low amplitude prefrontal waves (so-called "contingent negative variation," or CNV) seem to be associated with anticipation of delayed events (see Fuster 1980: 96, Stuss and Benson 1986: 70). Moreover, hypocampal theta seems to be an artifact of a general pacemaker function (see Gray 1982). The relations among these various slow wave artifacts and perceptual epochs is not known, but they almost certainly involve the temporal organization of cognitive and perceptual functions.
Perceptual Intermittency and Alpha Rhythms
Hidden to naive perception is the intermittency of "fulfilling" dot fields that arise and dissolve in epochs and that entrain with other cognitive functions to co-produce the "natural" (i.e., serial) present. For mundane consciousness, intentional and perceptual ordering are perpetually focused upon secondary and tertiary abstract relations (Husserl's "noematic acts"), rather than upon the epochally arising, serial march of the fields of dots are the "primordial fulfillment" of those relations. Yet, dots and epochs are actual and there for the trained contemplative to apprehend. That Husserl realized the perceptual epoch ("now point") as essential in experience and not merely an idealist abstraction is clear from comments he made in both his The Phenomenology of Internal Time-Consciousness (1964: 48, 57, 60, 62) and in comments recorded in Cairns (1976: 17).
There exists an important literature in the neurosciences relevant to our discussion of sensorial epochs. This research is ongoing and there remains a good deal of controversy on findings and interpretations in this field. Nonetheless, this research is suggestive of the neurophysiological substrate of perceptual epochs -- epochs being variously termed in this literature "perceptual moments," "temporal frames," "excitability cycles," "central intermittency," and "perceptual frames;" see eg. Varela et al. 1981). There is substantial evidence for some sort of central temporal processing mechanism based upon a minute perceptual unit within which temporal discriminations cannot be made (see Sanford 1971, Harter 1967, Steriade and Deschenes 1985, Efron 1970 and Childers and Perry 1971 for relevant reviews). Stimuli of different durations which are phase-locked to cortical rhythms and presented within an epoch will be perceived as simultaneous, whereas stimuli presented across epochs will be perceived as sequential (Varela et al. 1981), or in apparent motion (Ramachandran and Anstis 1986). The duration of an epoch seems to average around 100 msec (1/10 of a second) and is equivalent to the wavelength of the EEG cortical alpha rhythm (Childers and Perry 1971).
The extent to which cortical EEG reflects the precise phasing of local sensorial events remains uncertain. Evidence reported by Gho and Varela (n.d.) suggests a more complex relationship between epochs at the local sensorial level and global measures of cortical EEG of the sort reported above than previously thought. Nevertheless, perceptual epochs would still seem to exist and last roughly 100 msec, thus producing a basic unit of perceptual time within which temporal discriminations cannot be made.
The arising and dissolving of fields of dots occurring within a single epoch thus provide spatial extension without temporal seriation. This is, for the contemplative, the experientially pure form of Whitehead's (1978) "mode of simultaneity." Essential temporal relations which participate in constituting enduring objects and events -- relations such as the waves and drops discussed earlier -- are mediated by neural entrainments established across multiple epochs. (4) This is the experientially pure form of Whitehead's "mode of causal efficacy."
The function of the sensorial epoch may prove to be one of synchronizing parallel processes involved in constituting a unitive experience. This suggestion would be in accord with the so-called "excitability cycle hypothesis" (see Harter 1967) which posits epochs of sensory delivery into consciousness. This is the hypothesis best supported by the neuropsychological data so far.
Contemplation also supports this hypothesis, for the direct experience of sensorial epochs is of pulsing intermittency in the arising and dissolving of fields of dots. Cognitions pertaining to apparent motion involve tracking changes in spatial relations between epochs. Mind you, the activity of dots within an epoch is vivid and dynamic, not static. There is activity within the epoch, but no temporal attributions obtain within it. Temporal attributions are imposed by cognitive abstraction upon patterns and relations maintained between epochs. Direct experience also argues for caution in presuming that the activity of dots, and the sensorial structures mediating dots, are necessarily time-locked to stimuli. There is a great deal of spontaneous dot production in the sensorium apparent to direct perception and due no doubt to the fact that the structures mediating them are organizations of living cells that may, and often do produce intrinsically initiated activity. I suggest that direct contemplation supports Pinneo's (1966) distinction between the "phasic" (time-locked to extraneous stimuli) and "tonic" (intrinsically initiated) activity of sensorial structures.
1. 1.For a useful, but neurophysiologically naive discussion of intentionality, see Searle 1983.
2. 2.Please do not confuse my use of the term epoch with Husserl's "epoche." There is no semantic overlap intended.
3. 3.It is a curious fact about meditation upon bodily sensations that they will not directly lead to full absorption, but only indirectly by producing the "secret sign" ( patibhaga nimitta ), or image associated with that sensation. Absorption ( jhana ) upon the breath is into the sign, not into the raw field of dots that is the sensation of the breath passing by the nostril. The meditator learns to control their mindstate by choosing whether to shift concentration to the sign, thus inviting absorption, or to remain with the breathing sensation, thus avoiding absorption. Trained contemplatives come to utilize this control ("warp control;" see Laughlin et al. 1986) to access the bliss-energy released by attaining the absorptions, and then utilize this bliss to strengthen their concentration upon the dissolving aspect of the breathing sensation, thus setting the stage for the attainment of the nirvana experience.
4. 4.Patterns of entrainment across epochs constitute, when they become apparent to contemplative awareness, the most subtle grade of what we have called phases and warps of consciousness (see Chapter 1; see also Laughlin et al. 1986, Laughlin, McManus and d'Aquili 1990).