SENSORY INPUTS & PERCEPTION
When sensory information is organized, identified and interpreted in order to comprehend the surroundings it is construed as Perception. Perception encompasses signals in the nervous system, which is a result of physical stimulation of the sense organs (for e.g. light striking the retina of the eyes to eventuate vision, odour molecules precipitating smell, pressure waves augmenting hearing, taste buds and sense of touch). Our brain receiving these signals from our sensory organs and interpreting the information is just the passive part of perception however the brain does something more remarkable in terms of active interpretation by drawing from memory, learning, anticipating, familiarity cues, our motivation, expectation, presuppositions, past experience, one’s own emotional state etc. to amplify information for a distinct interpretation which is unique to each person.
Immense research has been done on perception from various standpoints for instance Psychophysics measures the effect on perception by varying the physical qualities of the input, sensory neuroscience studies the brain mechanisms underlying perception and philosophical perception studies explicates how to calibrate the extent to which sensory qualities such as sounds, smells or colours exist in objective reality rather than the mind of the perceiver. This blog doesn’t scope out clarity on the psychophysics, sensory neuroscience, neurobiological or clinical side of the brain that aids perception rather it attempts to understand the information interpretation aspect of the brain that coalesces into perception.
BEYOND SENSORY INPUTS TO THE BRAIN
One amongst brain’s myriad functions is to enable us to perceive the world around us as stable regardless of whether the sensory inputs are complete or partial. To illustrate this aspect let us take the case of Vertigo. Labyrinth is the part of the inner ear (vestibular system). Due to a virus infection the rotational and linear sensing abilities of the vestibular system is impaired. The brain combines visual cues coming from the eye with the sound cues coming from the ear and makes adjustments for balance. This is how we walk and run with consummate ease.
In the case of a person suffering from Labyrinthitis (infected labyrinth; a severe case is called vertigo), the brain receives just visual cues from the eye but remains bereft of auditory cues from the ear, which affects balance. Even if the person is in bed, the room appears to be turning around. This is because the signals being sent from both organs (eye and ear) are unequal and the brain interprets the difference as constant movement. Eventually the brain recognizes the incorrectness of the signals from the ear and compensates by taking over that erroneous vestibular function thereby restoring balance. This is called ‘compensation’ by the brain. This goes to prove that sensory inputs are just one aspect of perception and apart from these sensory stimuli, there is prodigious processing and sequencing going on in the brain to aid perception.
From the French philosopher Merleau-Ponty’s work ‘The phenomenology of perception’ it is inferred that traditionally the ‘notion of sensation’ was not a concept born out of reflection but a thought directed towards objects. Science pursued objectification and construed that human beings receive sensory stimuli and this is perception but apart from these sensory stimuli there are other meaningful patterns the brain constructs. What are these meaningful patterns, let us delve a bit deeper.
I. BOTTOM UP VS TOP DOWN APPROACH IN PERCEPTION
As per Goldstein, perception proceeds in 2 major ways. Bottom up processing (start from the bottom i.e. raw sensory data) and build upward into a complete perception in the brain and the reverse i.e. many experiences are organized using one’s knowledge of the world (pre-existing knowledge), called top-down process. Perceptual expectancy and experience are examples of top-down process and let us attempt to understand these through the following analogies:
a. Perceptual expectancy:
- Michael McIntyre the British standup comedian, before his gig begins, as he arrives at the stage itself, people start laughing. His own laughter triggers the hilarity amidst the audience. People’s past knowledge about Michael is enough to create this perception.
- Pre-recorded or induced crowd laughter after each gag coming from the television sitcom for instance ‘Friends’, changes our perceptual expectancy and it elicits both, laughter from us as well as intensifies the amusement.
- In spite of a loud room, the sensitivity to hear our name or hungry people instinctively alerted to the smell of food or in a deck of playing cards when spades and hearts were made red colour, the reaction time becoming slower are examples of perceptual expectancy.
- Arnold Schwarzenegger won Mr. Olympia contest 7 times, then became a Hollywood action icon and later Governor of California. Without ascertaining Arnold’s efficiency in movies the perception of people was that he has a great body, perhaps he will click in action movies and this proved right. Similarly this concept was extended to politics and he became Governor of California. People thought he is a movie icon perhaps he may do well in public service hence they voted for him based on perceptual expectancy.
Receiving sensory input is fine in comprehending the present scenario but past experience is vital in enhancing the overall experience for instance:
- Wine tasting: One needs a memory archive albeit small to identify the refinements in the taste of wine.
- X ray deciphering: How doctors in just one glance can indicate the anomalies.
- Music appreciation: How same song if heard multiple times creates a linking as against heard once.
- Sensory enhancement: Say you hear a song once, you like it fine. The song could trigger nice memories and make it experiential for you. Next time you hear it you happen to focus on the musical instruments used which heightens your awareness to various percussive volleys of sound. Later you see the same song being played live in a concert and you get a feel of the musicians who play it. If the music gets picturised for instance Sound of Music then the visualization association with the same song intensifies. In the movies My Fair Lady and Moulin Rouge the drama associated with the song shimmer visions inside the viewer’s head and instead of leaving you to your own imagination with the song, the directors create context, drama and relevance for you. Then with curiosity you check out the song on ‘YouTube’ along with its lyrics and now you understand the meaning. Later you read about the history of the song and find out the original intended meaning with which it was written, and the experience begins to amplify. When you go to Salzburg and take the ‘Sound of Music’ bus tour it emblazons the overall experience. If you have heard any song in the 60’s for example on a special occasion and enjoyed it with someone close, it triggers a different experience if the same song is heard 40 years hence.
In essence what I attempt to designate through these arguments is that experience and past memory play a significant role in overall perception of a situation and it is not merely sensory stimuli received at that particular moment that aids perception. Since each person perceives the world based upon a combination of sensory stimuli and a recall or reconstruction of own past events from experience retained in memory, the final narration of any incident or experience is just an interpretation that may or may not be the objective truth. Anybody’s feedback therefore about any incident, about others, situations, risks, opportunities, character assessment, own life etc. is merely ‘an’ interpretation amongst many others possible. This interpretation is based on their sensory inputs at the moment and the perception they have formed in their brain from past data and conditioning. There is considerable room for error here hence the listener has to be wary of this.
II. INTERPRETATION ASPECT OF PERCEPTION
Let us now essentialize the basics of non-sensory aspects leading to perception.
Gregory and Irvin Rock had stated that “Perceptual studies reveal inferential and predictive processes to be central to perception, we do not merely react to sensory signals by rigidly associating them with past experiences; our interpretational processing is far more complex than that.” Spinelli goes on to suggest that most phenomenologists and perceptual psychologists conclude that each of us experiences an interpreted world and not the one directly accessed by our senses. He further suggests that whatever object each of us perceives at any given time depends on the nature of the actual stimulus (sensory), our previous experience, the background or setting in which the object exists, our feelings of the moment and our general prejudices, desires, attitudes and goals.
Look at this study done by neuropsychologist Richard Gregory, an interesting aspect that is also featured in Malcolm Gladwell’s book. Sidney Bradford went blind at 10 month’s of age but regained sight after receiving a corneal graft at age 52. Upon removal of bandages, he heard a voice coming to him from one side and he turned to the source of the sound and saw a blur. He realised that it must be a face. Upon careful questioning he said he wouldn’t have known it is a face had he not previously heard such voices from other faces. What made Bradford see a blur? He had the access to the same visual information as others, light entering his retina was identical, same retinal image went to his brain but he saw differently as he lacked knowledge which was drawn from experience which is required to mould the sensory data into a meaningful form. Bradford had never seen a face before in his life hence there is no memory of a face in his brain where a comparison can be made with the sensory data now freshly coming from his newly restored eye hence Bradford saw a blur. The brain is actually taking the sensory input and doing some intense work and drawing inferences from memory to give us the appearance of a face, sense of movement etc. hence memory & past data are important and mere sensory inputs aren’t enough to aid perception. Both cases collude to the conclusion that sensory information is just one aspect in perceptual inference.
Ernesto Spinelli, the British existential psychotherapist suggests that perceptual processing is absolutely pervasive. Any new noise however novel or unusual a stimulus, our common response is immediately to associate it or identify it with something that is already familiar to us. On the basis of the schemata built up from past experience, we infer it’s meaning and react to the perceived stimulus. It is probable that the vast majority of our daily sensory experiences are perceived in a habitual manner, based on repeated previous experiences.
E.g. we smell coffee percolating and visualize breakfast being prepared, child hears the garage open and concludes mom is home. In the book Future Shock by Alvin Toffler explains this through ‘durational expectancy’ concept. From infancy onwards the child learns that when Daddy leaves for work in the morning, it means he won’t return for many hours. If daddy does then something is askew, the child senses this. The child soon learns that “mealtime” is neither a one-minute nor a five-hour affair, but that it ordinarily lasts from 15 to 45 min, going to a movie lasts for two to four hours, a visit with the pediatrician lasts an hour, school day ordinarily lasts six hours.
In adult behaviour, virtually all we do, from mailing to making love, is premised upon certain spoken or unspoken assumptions about duration driven perceptions. In reacting to such cues we have, more accurately trained ourselves to jump to conclusions from partial yet familiar stimuli from the previous experience. Toffler infers that it is these durational expectancies, different in each society but learned early and deeply ingrained, that is shaken up when the pace of life is altered. In the book ‘The culture code’ by Clotaire Rapaille he presents the ‘imprint’ concept. Most of us imprint the meanings of the things most central to our lives by the age seven. The very word ‘Christmas’ instantly imprints a perception of overall bonhomie in the brain; happy time, lights, presents, drinks, food, family and so forth. Multiplicity of interpretation is therefore possible that alters perception and how we construct our reality.
Edmund Husserl argued that the principle task is to strip away as much as possible the layers of interpretation added to the unknown stimuli to our experience in order to arrive at a more adequate approximation. To further magnify our sentience to the ‘perception construct’ , let us understand a concept proposed by Grossman and Don Ihde i.e. ‘Descriptive Concrete vs. Analytical Abstract’ , the essence of which is ‘describe, don’t explain’ .
To state an example, if I ask you how the movie Mission Impossible III was you may say ‘The cinematography was great, , pace was captivating, fight sequences were believable and gut-wrenching, editing and graphics outstanding but Tom Cruise seems to be a little older to work with younger heroines and must do more character roles’. Now the ‘descriptive concrete’ part of this narrative is everything else except ‘Tom Cruise seems to be a little older to work with younger heroines and must do more character roles’ which is the ‘abstract analytical’ part which is your subjective view and not the objective truth but the way conversation is structured it becomes difficult to segregate the descriptive concrete from abstract analytical. People take this piece of information about Tom Cruise and embellish it further with each person adding his own analytical abstract thereby misrepresenting the descriptive concrete thereby distorting perception. This phenomenon of one’ inability to segregate the descriptive concrete from the abstract analytical is one of the biggest causes for conversational impasse or misunderstanding.
The learning we glean out of this concept is that one may control one’s broadcast and present the descriptive concrete leaving the luxury of interpretation to the listener. Also whilst hearing any piece of conversation, we must attempt to segregate the descriptive concrete from the abstract analytical thereby increasing the propensity of comprehension of the right objective version of any experience. This is a useful cue in communication as it suspends subjective interpretations. As Merleau-Ponty the French philosopher puts it in ‘Primacy of perception’; there is no destruction of the absolute or of the rationality here, only the absolute and the rationality separated from experience.