D8 Use of Senses Flashcards
Visual Strategies
Tracking.
Tracing.
Scanning.
Eccentric Viewing.
Eccentric viewing is a technique used by people with central vision loss. the person looks slightly away from the subject in order to view it peripherally with another area of the visual field. ask student to look directly at your face and describe the details of your face. Have student shift eyes up, down, left and right and describe effect of changing eye position on ability to describe your facial features. Viewing clock on wall is another way. Experiment with different eye and head positions to see if they degrade or improve visual acuity. Goal is to determine position of face at it’s clearest.
Use of the off centre or paramacular (para meaning near or beside) area of vision for a clearer view (involves a tilt of the head or turning of the eye to one side or a combination of both to view around scotoma). Often children automatically develop compensation. Adults need instruction in locating and maintaining best eccentric area for fixating and viewing.
ask learner to look directly at instructor’s face and describe detail, shifting eyes in all four directions for each description.
Visual Scanning refers to systematic eye movement to search for a stationary object. teach systematic search pattern to getting them to search a wall or any large surface for a specific element such as a sign or clock. Get them to direct head and eyes to top left corner of wall. Then get them to trace from the left to right corner, then lower the head slightly and trace back to left side again, lower and repeat until target is located. Generalise to other locations, scanning for overhead signs or locating specific items in food store. systematic use of head and eye movement to search for targets , establishing and re-establishing lines of direction and finding landmarks. Learner should be taught to scan for a specific object, using both head and eye.
Visual Tracing is visually following a stationary line. Place objects at end of short lines of brightly coloured yarn, gradually lengthening yarn and complexity of surrounds, teaching student to search ahead for environmental lines of borders, lights, contrast etc Can assist in maintaining a desired line of travel. Visually following a stationary line, grass edges, hedge lines, baseboards, the visual counterpart of trailing with one’s hand or cane. follow base boards to bread for locating appropriate door
Visual Tracking is visually following a moving object. student starts seated while following moving targets such as people walking through cafeteria. Then have student begin walking and look for moving targets, gradually increasing complexity until they’re following other pedestrians in crowded areas. Practice tracking cars through busy intersections. visually following a moving target, following the shoulder of a person walking in front of you, following cars through a busy intersection and discerning whether they’re turning or continuing. A person can follow the shoulder of the person in front of them and watch for the rising or lowering to indicate ramps or stairs. Street crossings: watch cars at an intersection.
Need to have good O&M skills to complement these strategies such as:
- Primary Mobility Aid.
Build trust in primary mobility aid information so learner can look up and use residual vision for better pre-warning. - Depth Perception Cues.
Cues that could assist in locating stairs include, slope, height change of people in front, jagged or broken edged shadows, right angles or triangular shapes alongside border where riser and adjoining step meet, contrasting strips at edges of steps, emanating sounds from above or below such as voices or footsteps. - Visual Landmarks.
Distinctive shapes/colour, scanning upper field of view and remembering forward and reverse sequencing of visual landmarks to facilitate learning routes. - Glare and light adaptation.
Wearing absorptive sun filters to shield from glare, visors or wide brimmed hats, movement by changing angle of viewing to reduce or eliminate effects of harsh light and improve readability, night vision technology, conducting lessons in low light and night time conditions, evaluating light adaption times from indoor to outdoors and vice versa to help students understand how long and to what degree visual functioning is affected by changes in illumination. Some students may experience periods of no functional vision and may need to step aside and wait, use a guide or use a cane to manoeuvre safely.
Optical Devices
Telescope and Bioptic Telescope (fitted to glasses and fills in details of central vision e.g. road signs).
Used with visual skills of tracing, tracking, scanning and eccentric viewing.
Reduced visual field when looking through telescope.
Emphasis is on developing good visual skills such as tracing, tracking, scanning and eccentric viewing prior to introduction of optical devices.
Reduced visual field and possible eye strain
Optical device can reduce visual field and cause possible eye strain. You need to have a discussion with a student about his/her optical device to discuss most efficient use and proper care for the device.
Possible options include, telescopes, bioptic or head mounted telescopes (monocular or binocular units mounted on spectacles), visual enhancement systems such as Fresnel prisms & magnification systems.
Telescopes.
Localisation and Stabilization. Teach alignment of the eye, device and object with steady balance and consistent grip. May require resting the elbows on a hard surface or holding a telescope with both hands.
Focusing. Once an object located student turns mechanism a quarter turn to the right. Continue this until image is clear. Then practice turns to left. Then distance of object needs to be considered – objects far away are viewed through telescope at a short length and objects that are close require telescope to be extended to a longer length to attain best focus.
Scanning.
Systematic use of head and eye movement using device to search for targets. Then developing different scanning patterns based on the location and orientation of the target. Pole that holds sign is vertical. Horizontal scanning will provide quickest approach to locating pole. Or if looking for name of business along a building line, vertical scanning will locate signs and then horizontal to read each sign.
Tracing.
Following stationary lines in the environment, a precursor to tracking people or vehicles that are moving. Ask student to view through telescope while moving their head to trace along lines such as baseboards, grass lines, outlines of house, furniture and storefronts.
Tracking.
Maintaining constant alignment of eye, device and object while it is in motion. Easiest when object is at a far distance because of the relationship between visual field and object. Gradually increase speed of targets. Practice tracking cars and pedestrians, sports events, concerts or TV viewing.
Bioptic Telescope is a lens system with a telescope attached to a pair of glasses, above one’s normal line of sight. This allows a trained user the opportunity to detect objects or movement within his/her driving scene using the wide field of view available through the regular spectacle lens and to resolve fine details such as road signs and traffic lights by glancing briefly and intermittently into and out of the miniature telescopic unit
Tactile Information for O&M
Wind, sun, long cane (materials, slope, elevation) and trailing.
Wind cues that a street is being approached or that an alley or some other break in a row of buildings is being passed
Sun cues cardinal direction.
Long cane gives tactile information to perceive the material, slope and elevation of the upcoming walking surface and location and dimensions of obstacles and openings along their paths.
Trailing cues for door opening. driveway may be rough compared to smoother footpath indicating a veer.
Time distance estimations
Built through repetition, understanding of how long it should take to cover a distance.
Anticipate things like a turn without following shoreline, decrease reliance on tactile landmarks
Established through repetition of travel between two points at a consistent rate of walking. Also use other sensory info along route to compliment their general understanding of distances travelled. Work on this to support greater efficiency and decreased reliance on tactile landmarks which can be cumbersome. This can then help to anticipate turns to intersecting footpaths without having to follow a grass line with cane, thus increasing rate of travel.
Echolocation
Reflected sounds.
Passive with incidental sounds
Active with intentional sound (click, hand clap)
Echolocation is defined as the use of reflected sounds to detect the presence of objects such as walls, buildings, doors and openings. Sometimes referred to as obstacle perception.
Passive echolocation is when sounds are incidental in environment, hearing own footsteps, rustling of clothing or tapping of cane. Sound sources include wind, water, birds, crowds, office noises, traffic, weather, urban canyons, Doppler effect (train, plane, large trucks), yard work (mowers, whipper snippers), construction sites, dishes clanking.
Active echolocation is when an intentional signal is produced, like a click or handclap. Kish says the image is more precise, giving info about location, dimension (height and width) and depth of a structure (solid, sparse, reflective or absorbant). Can then form functional images of the environment for hundreds of yards. Sources include cane technique, footsteps, fingersnaps, clickers, rustling of clothes, hand claps.
Affected by:
Degree and type of hearing loss
Ambient auditory distractors
Training, practice, experience
Size and distance of objects
Background noise
Early onset and duration of blindness.
Strategies for helping to develop echolocation include exposure to echoes, exploring a variety of sounds at different distances. Practice activities for Use of Audition for Independent Travel in Natural Settings.
Sound shadow is an area of diminished sound created by the blockage of background sound by a large object positioned between the listener and the sound.
Sound masking is a loud sound that can mask the presence of other sounds intended to car.
The Doppler effect is the increase of frequency of sound produced by compression of sound waves and shortening of wavelengths as distance decreases between sound source and object. Basically car beep, siren, jet plane has higher pitch when approaching you and lower pitch when going away from you.
Kinesthetic and Proprioceptive information
Coordinate body movements (rate, timing, force)
Recognise location (slope, intersection)
Proprioceptive (awareness of posture, movement, and changes in equilibrium and the position, weight, and resistance of objects )
Kinesthetic (perceive the extent, direction, or weight of movement)
The learner can make accurate turns when using accurate kinesthetic and proprioceptive information. The learner knows where his body is in space. Proprioceptive system helps to identify and precisely coordinate his movement based on laterality, directionality and spatial awareness. Kinesthesia gives him the awareness.
A learner can use kinesthetic and proprioceptive information from slopes to recognize whether location on a path or danger such as intersection.
Feels angle of ankle change putting her toes below her heel.
Feel slope and finds body pushing up against gravity to ‘climb a hill.
Successful proprioceptive inputs provide awareness of movement, including the rate and timing of movements and the force exerted by muscles. Awareness of movement called kinesthesia and is the interaction of tactile, proprioceptive and vestibular inputs. All movement operates on a feedback system, either visual or proprioceptive, and the latter sense provides the only means by which people who are blind can identify and precisely coordinate movement.
Proprioceptive sensory additionally plays major role in several other areas of motor functioning. Foundation on which body awareness can develop and secondarily contributes to laterality, directionality and spatial awareness. Proprioception also connected to muscle tone and balance, isolate motions at individual joints and development and maintenance of good posture.
Proprioception describes the awareness of posture, movement, and changes in equilibrium and the knowledge of position, weight, and resistance of objects in relation to the body. Kinesthesia, however, refers to the ability to perceive the extent, direction, or weight of movement.
Often the kinesthetic sense is differentiated from proprioception by excluding the sense of equilibrium or balance from kinesthesia. An inner ear infection, for example, might degrade the sense of balance. This would degrade the proprioceptive sense, but not the kinesthetic sense
