William James said that 'an idea, to be suggestive, must come to the individual with the force of revelation.' While I agree that an idea that comes to an individual with revelation will be suggestive, I don't think it is necessary that the force of revelation be associated with an idea to be suggestive. Suggestive, in the sense of having some influence on a current state of being, revelation, in the sense of a sudden realization of something unknown. An everyday idea that would not be considered a revelation; it is healthy to drink water each day. This is not a revelation by any means. Yet, for me to tell you, right this second, "it is healthy to drink water each day", is an idea that is suggestive. There is no way to 'un-do' the idea that just entered your mind, it has happened, and therefore, like a raindrop falling in a pond, it will ripple through your current state of being and cause it to recalibrate thinking. As Heraclitus put, 'no man ever steps in the same river twice, for it is not the same river, and he is not the same man'. Admittingly, James' quote could be taken out of context if he used the term 'suggestive' to mean an idea that produces a change in action. So where the idea of me telling you drinking water everyday does indeed influence a subtle shift in brain-state, if not taken with the force of revelation, it will not influence your subsequent expressive output. Undoubtedly, influence will occur, though it may be possible that there is a threshold of influence that needs to be passed before the idea will alter actions. Recalling the metaphor of a raindrop in a pond, we recall that an event has reverberations, this brings to mind a slight alteration of James' quote...
"A stimulus, perceived by the senses, will be suggestive."
Unless you are dead, the brain is never 'off'. It is constantly in activity, in fact, no two moments are ever the same. Each moment is a permutation, a slight oscillation in the pattern of neuronal firing. One way that neurons fire is through the transfer of information. I am using information to mean any external stimulus, it could be speech from another person, the bright colors of the flower market, a light brush from a passerby, the aroma of curries in the air, the taste of fresh Naan bread, or a horn. Any stimuli that is acquired through the senses (visual, auditory, tactile, gustatory, olfactory) will directly have casual influence on the sensory processing level. For example, if a flash of light occurs while my attention is engrossed in a task, there is a potential that the flash of light will not 'register'. Though, the flash of light inevitably will be processed in the visual system. If I asked the person, 'did you see a flash of light'?, and they replied that they had not, this would constitute not 'registering' the flash of light and thereby not consciously perceiving it. When I say not consciously perceived, I mean that there is an absence of awareness of the occurrence of an event. This is not to say that the flash of light was not perceived by the visual system. This, as I said, is inevitable, and I reason that this conscious-less perception will have a direct effect on subsequent conscious perception of similar stimuli.
This phenomena has been well established at the behavioral level, it is called priming. For example, imperceptibly flashing the word 'table' before a task will increase reaction time in recognition of the word 'chair' compared to the word 'goat'. This is due to the conceptual similarity between table and chair. The semantic process is primed in the category, and therefore the component is accessed more efficiently from the lexicon. But where does this priming take place? There is reason to believe it is at the perceptual-encoding level. Recently, experiments have been carried out on 'multisensory processing'. One of my favorite experiments in this area is actually an old one, it's called The Rubber Hand Illusion. The set up is relatively simple, but the subsequent effects are fascinating. The materials needed: A person, a box, a rubber-dummy-hand, and two feathers. In this experiment, the subject places the left arm inside of a box in order to occlude it from the visual system. The dummy arm is lined up in proper orientation to replace the occluded left arm, as if it was the subjects own arm, the orientation is crucial, it has to be physically possible. So, you have your arm in a box, and there is a dummy-hand in front of you, what is happening? Well, nothing much, yet, but incredible things start happening to perception once one more sensory system is involved in the task. This is where the feathers come in. Both the index finger of the dummy and the occluded hand are simultaneously and repeatedly stimulated through a feather stroke. The visual system input is the dummy-hand being touched by a feather on the left index finger while the tactile system input is being touched by a feather on the left index finger.
These two signals must be integrated, and they are, this results in a change in proprioception, or body awareness. Ownership is shifted from your actual hand, to the dummy-hand! Some participants even report that they 'feel' the touch emanating from the dummy-hand, rather than their own hand, the sensation of touch is shifted through the sensation of sight.
An illustration:
Green: Tactile stimulus
Bright yellow: Visual stimulus
Light blue: Proprioception shift
(From Botvinick, 2004)
As it turns out, there is something called peripersonal space, which is the space around your body. It is best established in the literature for the hand, this space potentially aids in tasks utilizing hand movements. The visual neurons that respond to this peripersonal space start orientating with the dummy-hand! If the dummy-hand is moved, these cells respond to the new orientation accordingly. Now, something interesting happens when the visual and tactile stimuli become asynchronous, meaning the temporal order of the feather strokes are disrupted. The illusion instantly crumbles! The synchrony of the stimuli is critical for the fusion of the senses to occur. The sensory system processes stimuli as either from a common source or separate sources. Temporal bisensory synchrony and orientation trick the perceptual system to perceive the stimuli as arising from a common source.
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A quick tangent: Interestingly enough, there is a condition called 'Somataparaphrenia' which is the polar opposite of the Rubber Hand Illusion, in that here the person does not believe that their own limb belongs to them. The self-awareness of body ownership is absent. Another fascinating case implicating the same brain regions is that of hemisphere neglect, this occurs when damage occurs to a part of the brain called the 'right parietal cortex', the same part thought to be responsible for the fusion and recalibration of the visual and tactile senses in the Rubber Hand Illusion. Name aside, the repercussions of damage to this area are a complete neglecting of the contralateral hemisphere of space. They don't see the left side of the world. There is documented cases of patients only shaving one side of their face, or eating half of their plate of food... when the plate is rotated 180 degrees... they are genuinely surprised to find food! Typically, there are two different forms that neglect is found: spatial and object. In spatial neglect, the left hemisphere of space is neglected. In object neglect, the left side of objects are neglected. For example, in spatial neglect, the neglect is across space, if asked to draw a clock positioned in the left hemisphere of space, they would report not seeing a clock. In object neglect, the neglect is across the object, if asked to draw the clock, they will draw only the right side, the numbers 12-6, completely neglecting the left side of the object. However, they do draw a circle, this is thought to be due to the automatic-nature behind drawing circles. Interestingly enough, hemisphere neglect primarily occurs only when damage is to the right parietal cortex. This is thought to be due to the parietal cortex's lateralization functions: the left PC is thought to create a representation of only the right hemisphere of space, whereas the right PC is thought to create a bi-lateral representation of both the left and right hemispheres of space. Therefore, when the right PC is damaged, the bi-lateral representation is impaired and there is no longer any representation of the left hemisphere of space.
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How does this all relate with the statement"A stimulus, perceived by the senses, will be suggestive."? Well, what is experienced in the case of the Rubber Hand Illusion is sensory recalibration. To explain this further, I will look at a recent experiment in multisensory processing utilizing auditory and visual stimuli that emanate somewhere between -26º and +26º on the horizontal plane. In this experiment, there are three presentations of stimuli: (V1) a flash of light occurs, (A1) a pulse of sound occurs, (V1A1) a flash of light simultaneously occurs with a pulse of sound. The researchers found that when the spatial discrepancy was large on V1A1 conditions, for example, 26ºs, (i.e. the visual stimuli is presented at 13º, and the auditory stimuli is presented at -13º) there was a 2º shift in the perception of A1 on the subsequent trial. In other words, the perceived location of sound is spatially-recalibrated to the right on an auditory only trial when the previous bisensory trial presented a visual stimulus to the right of an auditory stimulus, and vice versa. This supports the statement"A stimulus, perceived by the senses, will be suggestive.", as the visual stimulus is directly influencing the auditory stimulus through passive perception.
...Each stimulus that our senses perceive is like a raindrop, rippling through our consciousness.
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