TACTILE PERCEPTION

Post 55 -by Gautam Shah

(Lecture series: Space Perception -Article-IX of 15delayed documentation)

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Our Sense of Touch is controlled by a complex somatosensory system. It is a network of sensory neurons and neural pathways that responds to changes both, at the surface or inside the body. It covers all the tactile sensations, like cold, hot, smooth, rough, pressure, tickle, itch, pain, vibrations, etc. The Tactile experiences act as reinforces for other sensorial encounters. Tactile or touch perception not only modulates our experience of objects but, senses the affectations of the climate. A touch receptor node is very adaptive, as it can immediately senses the changes. These changes include start and end of the touching and any variation within it.

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All sensorial nodes of perception are fairly localized, except the touch. Touch nodes are fairly spread across the body, though some of the body parts are more sensitive (face, hands -finger tips) than others. Tactile perception, if corroborated by other sensory perception, it reinforces the experience, but this is not a perquisite.

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Typically, the perception of textures of Visual and Touch, need mutual confirmation. So we try to feel the surface as soon as we have seen it. Tactile experiences are generally real, but could be presumptive. We tend to presume or relate certain experience under specific environmental conditions. Brightness and warmth or darkness and coolness are co-related. Similarly air movement (on skin) and freshness (smell), are related due to dilution of foul air. Elevation (territorial) is sensed by body as drop (or rise) of air pressure, but reinforced by the reduced (or increased) proportions of oxygen in breathing.

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Experience of Texture as touch, have several components, like the roughness, direction of grain, movement direction of the body limb, surface temperature, moisture, immediate pre-experience, past remembrancers and associated environmental conditions. All these act as arousal or diffusing factors.

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Perception of Visual texture depends, degree of gloss, colour, angles of illumination, and past touch associations like warmth, stiffness, etc. The expectations for a visual texture as aroused for a certain tactile experience, plays a great role (or other way around, the expectations for a tactile texture as aroused by a specific visual encounter). The dis-confirmation between the expectations and real experience is always very exciting an affair.

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The exciting affair is based on Two factors. The Contrast (expectation versus real experience) is remarkably acute, or the experience is Confirmative. One can design for the tactile-visual experiences for both, non-affirmation or confirmation. With e-commerce, we have to perceive the tactile details from only visual feed. We learn to judge the texture by relying on past experiences, but the visual feeds in e-commerce are continually manipulated, and so, impressionistic.

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While dealing with products, the textures are experienced through not just hands, but for personal or wearable items the contact with the relevant skin areas is involved. ‘Perception of touch has Three manifests. 1 Passive touch, where one is being touched like the caress (being touched upon), 2 Active touch, where one discovers the touch as a voluntary action, but explores it further, and 3 Interactive touch occurs with the encouraging response.

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Massage is a tactile craft of relaxing body muscles. It is carried out by hand, feet, knees, heated stones, woods, etc. and using many different mediums, like hot air, smoke, water, oils, extracts, flour dough, vibrations etc. The earliest word for massage in Sumerian and Akkadian texts of Mesopotamia was muššu’u. Massage word comes from the French massage (=friction of kneading) and from the Arabic word massa (=to touch or feel). There is another word of the Portuguese origin, amassar (=knead), from the Latin massa (=mass or dough)”, from the Greek verb massō (=to handle, touch, to work with the hands, to knead dough). A distinctive words in ancient Greek for massage was anatripsis, and the Latin word frictio.

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Touch is closely related to the identity of Five basic elements: Fire, Air, Water, Earth, Sky (nothingness). Each of these is experienced through Touch. Fire=warmth, Air=pressure, Water=moisture, coolness, Earth=Energy and Sky=life. The connections and interpretations vary from culture to culture, but all are part of spiritual, religious and human interaction practices of the world.

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Commercial merchandise managers encourage, one to try out the clothes, shoes, food items, etc. Here not just the ‘feel’, but handling or ruffling sounds, smells, electric charge, etc. reinforce the experience. To these reinforcements the ambience of place adds to the experience. These are some of the sensorial reinforcements not available in e-commerce or communicable media. Perhaps future will transmit such experiences.

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The Food Experiences are formed of several factors, such as visual, audio and tactile (hand and in the mouth -chewing, turning around with tongue adding of saliva and partial digestion) stimuli. These factors affect consumers’ likes and preferences of eatables. There are several words that describe the food experience as, soft, hard, rough, creamy, crispy, mushy, sticky, lumpy, liquid, solid, etc. These encounters relate to physical properties like density, viscosity, surface tension, and electrical charges, temperature, moisture and other tastes and odours. Food experiences also relate to ambience of the places (formed of place, serviettes, sequencing, gaps or delays and accompaniments).

15 Crowding can turn into bearable-acceptable or detestable touch with implications of Sex, age, religion, skin-colour, social strata , etc. edpix.comphotodownload1342409

Dysesthesia or Dysaesthesia =abnormal, inappropriate or unpleasant sensation of touch. The word comes from the Greek word, dys =not-normal’ and ‘aesthesis =sensation’.

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Presence or absence of Electrical Charge in objects has a great role in modifying the touch experiences. The objects include materials, products, foods, fabrics, shoes, etc. and architectural elements like table tops, furniture surfaces, floors, knobs, handles, railings, toilets, etc. These may gain charge on contact or on being rubbed (tribo-electric effect #). The charge may remain as potential due to poor conduction. Electric charge from lifeless things may create a detestable feeling. Electric charge is sensed through human to human touch like in case of accidental contact or conscious reach like a handshake, kiss, hug, caress etc. These later, interactions are more pronounced when the contact is casual brush to be shocking or little longer lasting for realization.

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# Tribo-electric (tribo=rubbing or friction -Greek) effect is from static electric charge. Its strength depends on the type of material, surface roughness, temperature, etc. When two materials can attract or deject each other depending on, if these are molecularly the same or different.

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Vibrations are experienced by skin through the mechanico receptors (The receptors perceive sensations such as pressure, vibrations, and texture). The mechano-receptors in the skin, sense four different stimuli of varied duration. The electro-tactile sensations are felt as vibration, touch, tingling, itching, pinching, pressure, and pain.

Merkel cell nerve endings are found in the basal epidermis and hair follicles, perceive low vibrations (5–15 Hz) and deep static touch such as shapes and edges. Tactile corpuscles sense moderate vibrations (10–50 Hz) and light touch. They are located in fingertips and lips. They help read Braille and feel the gentle stimuli. Pacinian corpuscles distinguish rough and soft substances. They react to vibrations around 250 Hz. These react only to sudden stimuli like clothes and hand-held tools. Bulbous corpuscles are slow to react but respond to sustained skin stretch. They have kinesthetic sense and control the finger position, detect slippage of objects, movement etc.’

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There are three tactile sensory systems, cutaneous, kinaesthetic and haptic. First two are referred to as tactual (active-passive) perceptions. The Haptic experience is active touch to communicate or recognize objects.

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Haptic (from Greek haptikos=Tactile or sense of touch) technology creates an experience of touch-reflex or acknowledgement by creating force, vibration, or motion to the user. It is also called kinaesthetic communication or 3D touch. These are used to control virtual experiences, like remote control of machines and devices (tele-robotics).

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Fabric-hand is a collection of several sensory perceptions. It indicates smoothness, compressibility, elasticity, creases, etc. of the textiles. It shapes the aesthetic qualities and perceived comfort of comfort. Drapability manifests from the ‘fabric-hand’. It combines effects of several factors, such as stiffness, flexural rigidity, weight, thickness, etc. Soft fabric drapes closer to the body forming ripples, whereas stiff fabric drapes away from the body. Stiffness of fabric itself depends upon ‘geometrical’ character of the fabric.

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