Recent neurological studies suggest the possibility that the executive areas of the human brain, primarily in the frontal lobes, manifest a high degree of sensory integration. This integration is found apparantly throughout the neocortex, both at the neuron level (Stein & Meredith 1993) as well as in groups of neurons and large cortical areas, for example the principle sulcus of the dorsolateral prefrontal cortex (e.g. see Goldman-Rakic 1984).
Implied in this is the possibility that the brain, when it performs abstraction, is relying on a hybrid sensory system. This paper analizes thought processes and the possible ramifications of hybridization on perception. (A 'logical' derivation of possible bimodal areas is given here)
The biases of the brain hemispheres of humans is well documented. An analysis of the literature suggests that a genetically integrated brain adapts to environmental conditions by developing biases. These biases seem to be, as far as the hemispheres are concerned, derived primarily from audition and vision. There is the suggestion that "..every infant is synesthetic, although most gradually grow out of it" p 12 (Stein and Meredith 1993). The term synesthesia means the joining of senses, and the implication is that environmental exposure instigates the preferred development of sensory biased areas; at birth differentiation is minimal, e.g. -
"There are observations that sound as well as visual objects evoke spatially coordinated eye movements in neonates. This has been known for some time in older infants, but now is being examined far earlier. There is at least one case in which auditory-evoked eye movements have been claimed within moments of birth, and in another a congenitally blind infant showed convergence of the eyes to approaching sounds and divergence of the eyes to receding sounds. The presence of a visual target is also known to enhance the spatial coordination of the eye movements evoked by an auditory stimulus in neonates. These observations are not explainable by mere arousal effects or traditional learning theories, and suggest a prenatal link between vision and audition, at least in terms of spatial relations." p14 (Stein and Meredith 1993)
"The idea that links between modalities are established prenatally is consistent with modern neuroanatomical findings, although we do not yet understand much about the synaptic or physiological consequences of multisensory convergence at such early stages. Newborn animals repeatedly have been shown to have well-organized inputs from differing sensory modalities converging on the same target structure. Presumably these inputs are also synapsing onto some of the same neurons. Indeed, at an anatomical level, the fetal and newborn brains of some animals may be thought as more multisensory than those same animals when they are adults, because they exhibit multisensory convergence in structures known to be unimodal at maturity." p14 (Stein and Meredith 1993)
I suggest that these biases, applied to the brain as a whole, allow for one hemisphere to develop fine audition derived skills but gross visual skills, and the other hemisphere to develop fine visual derived skills and gross audition skills.
Furthermore, closer analysis of these biases suggest that one hemisphere is bias to serialized information, and the other is bias to 'whole' information and that the 'whole' bias hemisphere is finely hierarchical and the serial bias hemisphere is finely relational.
What is of interest is that the serialized hemisphere can be hierarchical but only over time, and the whole biased hemisphere can be relational but also only over time (compares wholes). A good analogy is with a film. If I freeze the film at a specific frame, I will see rich visual details within the frame but relational details caon only be made with the next, or previous, frames. On the otherhand, the auditory track information will be lost when the film stops, and only grossly understood if I just play two or three frames, but becomes, potentially, extremely rich once the film is running.
It is important to recognize that, at the level of abstraction, the 'whole' biased hemisphere is NOT processing information in parrallel, it is processing information as a whole. There is a subtle difference here in that parrallel processing implies different serial tasks running concurrently on the same data, for which there is little evidence, whereas wholistic processing is simply processing of wholes rather than parts.
The best example of wholistic processing is the visual system, and here we see individual retina information being grouped into lines at the thalamus and this data abstracted to planes at the primary visual cortex. The apparent parrallel processing within the retina is abstracted (many into one) to present a whole at the visual cortex, and at the cortex end it is this whole that is delt with.
The best way to interprete the 'whole' bias is as a bias to pictures and the serialized bias as a bias to sound. Full capability is based on the hybridization of these two abilities into 'spatial' concepts and 'temporal' concepts applicable across the senses, allowing for temporalness in vision and spatialness in sound.
Generally, ANY information that has been taught to be serial in form is processed by the serialized bias hemisphere. This includes information derived visually. ALL other information is delt with as if it is a whole requiring breaking down. This includes information derived auditorally.
This model implies that there are two forms of meaning within a timeframe. One is based on hierarchy and the other based on relations. In any one timeframe, a hierarchy can elicit a somatic response (emotion) and a relation can elicit a response to syntax (This response to syntax has infact been found, with a bias to being located in the serialized bias hemisphere - see Munte et al (1993)) .
A fine emotional response to serialized data is only possible once the hierarchy has been developed over time. It is possible for tonal variations to introduce emotive content, but even here, these seem to be 'accumulated' as the serial information develops to it's final point.
Within a timeframe, emotional response is gross, or neutral, when compared to the whole bias hemisphere where rich emotional nuances are more likely.
What seems to create these hierarchies are the development of contextual levels. These are always present in 'the whole'; they can be seen. For novel serial data, these levels are built, where each contextual timeframe is linked. This generates a whole, which if stored is stored as a linked list of contexts (parts) developing from the gross context to fine context. Each part has a gross emotive marker (good/bad/neutral) that, when linked with the other parts gives subtle emotive variations.
Hierarchies manifest the development from gross to fine levels. They manifest the concept of refinement.
The synthesis of a whole, being either visual or auditory, requires an initial gross context. This context forms the foundation for the development of the whole; it's refinement.
The analysis of a whole takes the whole as the initial context which is treated as gross when compared to the developing levels of analysis that follow.
As we synthesis or analize, in each step, it is the previous frame that becomes the context for the next step. I use the term frame to include any relational data that we have derived from the context, or brought to the fore, within the current step - the current level of abstraction.
The initial frame consists of just the gross context. The next frame consists of the gross context plus any derived data. As we develop so the previous frames become the contexts for the next frame until we choose to stop or we run out of any further possible derivations.
This process of analysis is strongly associated with the bring to the fore previous 'background' data.
The process of synthesis is the building in the fore of what will become the whole and thus a future background, for once a part is put in place, it becomes part of the overall background when we consider the placement of the next part; a task that occurs in the next frame.
A developed hierarchy can be drawn as a tree, in this case binary:
ANALYSIS PATH
(Top-down)
D = Dichotomy; C = Context.
+------------------------------+
| THE FUNCTIONING WHOLE | L0
+------------------------------+
| A | B | D1 (C = WHOLE)
+---------------+--------------+
| c | d | c | d | D2 (C = a/b)
+-------+-------+-------+------+
| e | f | e | f | e | f |e | f | D3 (C = c/d)
+---+---+---+---+---+---+--+---+
| etc., | D4 (C = e/f)
--- -- -- -- -- -- -- -- -- --
| etc., | Dn
+------------------------------+
Fig P4.1 Explicit hierarchical structure.
A simple diagram of the process of synthesis introduces some
interesting concepts:
SYNTHESIS PATH
(Bottom-up)
+------------------------------+
| g(i) | h(j) | L3 (C = e/f(g/h))
+------------------------------+
| e(g) | f(h) | L2 (C = c/d(e/f))
+------------------------------+
| c(e) | d(f) | L1 (C = a/b(c/d))
+------------------------------+
| a(c) | b(d) | L0 (C = 0(a/b))
+------------------------------+
Fig P4.2 Implicit hierarchical structure.
For the synthesis path, the initial context (L0) can be either ZERO (Context-free - the paper on which we write, or the NULL set of set theory) OR a prime dichotomy (giving an implied gross context), or just an explicit gross context.
In the above diagram, for context-free we have dichotomy a/b. For an initial gross context we have dichotomy a/b as the context from which is derived the first distinction c/d, and so on.
The stacking, and thus apparent visually equal nature of the path levels, hides the development of contextual complexity, from the gross context of L0 to the refined context at L3. Neurologically, we can actually see this form of map in the primary auditory cortex, thus adding some creedance to our overall model.
The advantage of this form of structure is, simply, space. I can store the integrated hierarchy for four dichotomies (a/b,c/d,e/f,g/h) in three levels, compared to the explicit hierarchic map that requires four levels and a degree of redundancy. For any 'whole', the more levels I store, the less space I need, thus manifesting a GROSS/FINE bias where the previous context enables the process of refinement.
Having developed some foundation, at this point we consider the fundamental dichotomy within quantum mechanics, the particle/wave dichotomy.
The level of integration within the associative areas of the brain is such that we can include the probability of sensory hybridization, where the audition/vision systems share neurons.
The question is, what are the connotations of this? At the psychological level, there exists cases of mental states that seem to resemble the joining of the senses. This is called synesthesia. Synesthesia may be an example of hybridization or an example of strongly linked, but seperate, sensory cues responding to a stimulus. However, the senses can be seperated in that I am aware of seeing and hearing.
For example, I know someone who teaches singing. One of her methods is to teach her students to imagine the notes as colours and to use these colours to 'paint' music. She has used this since she discovered herself doing it; when she sang she saw colours. As we shall see, closer examination of this shows a link between colour, harmonics, and emotion. The colour/harmonics link is based on sound frequency (harmonics) being represented visually as light frequency; colour. The emotion link is the fact that it is frequency that strongly elicits emotional responses. This is easily detected by the adding of harmonics to a single tone, or the presentation of differing colours. Both systems can easily elicit varying emotive responses.
But what if hybridization creates sensory associative neuronal systems that are outside explicit associative awareness; systems that are unconscious?
There does seems to be an overall concept that is challenging to our culture, and this is the apparent duality that we seem to observe as a 'natural' manifestion of nature.
Continue with Duality (inc. reference list)