Unit 2 - Visual Perception Flashcards
Visual Perception
the total process responsible for the reception and cognition of visual stimuli including components of visual reception and visual cognition
functions of visual perception interaction
- Respond and adjust to retinal stimuli (requires anatomic and physiologic integrity)
- Move both the head and eyes to collect “raw” visual data (occulomotor and vestibule-ocular control)
- Effectively interpret visual information (visuoperceptual ability)
- Respond to visual cues through efficient limb movement (visuomotor ability)
- Accomplish integration of all these abilities
visual-receptive components
taking in visual information
Approximately 70% of sensory receptors in the human body are allocated to vision
Visual-receptive components depend on the integrity of anatomy and physiology of the eye structures (ie. cone, rods, pupil, optic nerve, etc).
visual fixation
the ability to maintain visual gaze on person or object. This is a prerequisite eye movement for higher level skills of tracking and scanning. Requires conjugate eye movements.
visual pursuits
visual tracking of a moving object, involves the continued fixation on a moving object so that the image is maintained continuously on fovea (located near the retina, it s the point of sharpest and clearest vision in the eye, it transmits the signal to the optic nerve).
• Typically seen as a child is following a ball throw to him/her, enable coordinated motor act of catching the ball.
• Pursuits are seen in infants 7 weeks of age (tracking parent), but is not fully developed until 16 to 18 years (Lane, 2005).
• Requires control of eye movements (oculomotor integrity)
visual saccades
visual scanning, the rapid change of visual fixation from one point in the visual field to the other. Seen in tasks of reading and copying, especially important for success in both tasks!
info about visual saccades
- The brain can’t handle all the visual information available to it, ¾ of the visual information available to the brain is ignored (Smith, 2014).
- When we read, we don’t take in large amounts of visual information
- In reading, the eyes “jump” from word to word so that when each word is fixated, it is processed rapidly and the next eye movement is planned.
- Saccadic eye movements start to develop during 2 to 5 months of age, but are typically inadequate until about 7 years of age. Many 5-year olds have difficulty performing saccadic eye movements accurately.
- During reading, we move our eyes from one fixation (word) to another fixation (word) by saccadic eye movements. When we move to the next word, the cognitive information continues, but the visual information should terminate (thus allowing for new visual information to be processed). ~75% of childrenwith reading disabilities have deficits with overlapping words (Smith, 2014):
How to spot a child with poor saccadic eye movement
Eye movements include head movements when reading
Frequently loses place when reading
Omits words when reading
Skips lines when reading
Is a slow reading, has to re-read lines that are missed
Poor reading comprehension
• A child in first grade only takes in about 45% of a word, pauses 224 times per 100 word, pauses for .33 seconds. (Vogel, 2015).
• Typically, a person can read 250 words per minute or about 4 words per second (Smith, 2014).
• During these short pauses of fixation, visual information is extracted and processed by the brain.
• by improving a child’s eye movement, you can help improve a child’s reading and copying speed and efficiency
acuity
the ability to discriminate the fine details of an object with clarity. 20/20 means that a person can perceive as small an object as an average person can perceive at 20 feet.
accommodation
– the ability of each eye to compensate for a blurred image. The process used to obtain clear vision (ie. to focus on objects at varying distances). Typically, only takes a split second for accommodation to occur.
binocular vision
The ability to mentally combine the images from the 2 eyes into a single perception. The 2 prerequisites for binocular vision include alignment of both eyes on object and the size and clarity of these 2 images are compatible. When this occurs, the brain can combine the 2 images into a single perception.
convergence and divergence
the ability of both eyes to turn inward toward the medial plan and outward from the medial plane.
Visual-Cognitive Components
the processing and interpretation of visual stimuli is a mental process involving cognition, which gives meaning to the visual stimulus.
visual attention
the selection of visual input
alertness
the child’s natural state of arousal
selective attention
the ability to choose relevant visual information while ignoring the less relevant information; it is conscious, focused attention
visual vigilance
the conscious mental effort to concentrate and persist at a visual task. The skill is exhibited when a child plays diligently with a toy or when writing a letter, completing homework.
divided or shared attention
the ability to respond to 2 or more simultaneous tasks. This is seen when a child is engaged in 1 task that is automatic while visually monitoring another task.
visual memory
the integration of visual information with previous experiences. Long-term memory is a “permanent” storehouse while short-term memory can hold a limited number of unrelated bits of information for ~30 seconds
visual discrimination
the ability to detect features of a stimuli for recognition, matching, and categorization. Includes the ability to note similarities and differences among forms and symbols and relate these back to information previously stored in long-term memory.
recognition
the ability to note key features
matching
the ability to note the similarities
categorization
the ability to mentally determine a category based on noted similarities or differences (ie. vehicles, animals, birds….)
form consistency
the recognition of forms and objects as the same in various environments, positions, and sizes. It enables a person to recognize objects even when there are differences in orientation or detail. The child’s ability to identify the letter “A” whether it is typed, printed, written in cursive, or italicized.
• Dramatic improvement between 6 and 7 years of age
visual closure
the identification of forms or objects from incomplete presentations. This enables a person to quickly identify objects, shapes, and forms by mentally completing the image or my matching it to information previously stored in memory.
figure-ground
– The differentiation between foreground and background forms and objects. It is the ability to separate essential data from distracting surrounding information. The ability to attend to 1 aspect of visual field while perceiving it in relation to the rest of the field, to attend to what is important.
• Improves between 3 and 5 years of age; stabilized growth between 6 to 7 years of age
spacial-perception
the determination of spatial relationships of figures and objects to oneself or other forms and objects. It is important in understanding direction and positional concepts such as out/in, on/off, up/down, in front/behind, left/right. Important when providing handwriting instruction.
• Development complete by 7 to 10 years of age
visual imagery
the ability “picture” people, ideas, and objects in the mind’s eye, even when the objects are not physically present. A foundational skill for reading comprehension.
observable cues to visual problems
- Misalignment of eyes
- Constant redness or tearing in eyes
- Complaints of headaches, dizziness, nausea, burning or itching
- Poor eye movement abilities
- Poor eye “teaming”
- Poor eye-hand coordination
- Poor visual-form perception
- Poor acuity
Motor Free Visual Perceptual Test (MVPT)
appropriate for children and adults ages 4 through 85 years. Designed to assess visual perception without reliance on an individual’s motor skills, the MVPT-3 is particularly useful with those who may have learning, cognitive, motor, or physical disabilities. The MVPT measures skills without copying tasks. It contains many new, more difficult items at the upper end for older children and adults. Tasks include matching, figure-ground, closure, visual memory, and form discrimination. Stimuli are line drawings. Answers are presented in multiple-choice format. Responses may be given verbally or by pointing
The Beery Test of Visual Motor Integration (VMI)
appropriate for children and young adults ages 3 to 18 years of age. Designed to assess a person’s ability to integrate visual and motor abilities. The Short Format and Full Format tests present drawings of geometric forms arranged in order of increasing difficulty that the individual is asked to copy. A normative sample of 2,512 individuals age 2 to 18 years was used for standardization. The short and long format tests should take only 10–15 minutes to complete and the supplemental tests taking only 5 minutes each. The Short and Full Format tests can be administered individually or to groups.
Bruinicks-Oseresky Test of Motor Proficiency
Sub-tests 7 and 8 deal directly with visual motor abilities (Visual-Motor response and Upper Limb Speed and Dexterity).
Test of Visual Perceptual Skills (TVPS)
similar to VMI assessment, more figures and scoring is involves more criteria.
Test of Handwriting Skills (THS)
print and cursive handwriting assessment, looks at letter formation, reversals, and speed of formation in comparison to peers.
common visual problems with Autism
- Poor visual registration
- Oculomotor dysfunction
- Poor visual attention
- use of peripheral vision over focal vision
* *Has strengths in form and space perception – puzzles**
common visual problems with CP
- Strabismus
- Oculomotor problems
- Poor ability to control and direct eye gaze
* *children with athetoid CP have FEWER visual perceptual disorder than other types of CP**
common visual problems with Cortical Visual Impairment
- Children with CVI can present very differently
- One child with CVI may have limited responses and skills,
- Responds only to light sources or a bright red toy
- Another child with CVI may demonstrate visual difficulty only in complex environments or with novel or visually cluttered materials.
- Milder forms of CVI may not be detected visual difficulty is attributed to such factors as communication-language or motor delays
common visual problems with learning disabilities
- Poor visual attention
2. visual-cognitive problems
common visual problems with prematurity
- Retinopathy of Prematurity
- Cortical visual Impairment
- Poor visual acuity
- Strabismus
- Astigmatism
common visual problems with traumatic head injury, stroke, tumor
- Homonymous hemianopsia
2. Poor body awareness, position in space
Approaches guiding treatment of visual perceptual difficulties:
- Developmental
• Higher level skills evolve from integration of lower-level skills
• The identification and remediation of deficits in lower-level skills needs to occur before proceeding to higher level skills - Compensatory
• Classroom materials or instructional methods are modified to accommodate the child’s limitations
• The environment can be altered or adapted
possible compensatory guidelines
- Limit the amount of new material presented in any single lesson
- Present new information in a simple, organized way that highlights what is especially pertinent.
- Ensure that the child has factual information
- Link up the new information with the information that the child already knows.
- Use all senses
- Provide repeated experiences to establish the practice until the child knows
- Group children with similar learning styles together
intervention - preschool and kingergarten
• Organize the classroom activities to help children develop the readiness skills needed for visual perception
• Educate teachers on using a “multi-sensory” approach with children who struggle with shape, letter, and number recognition
o Make letters with textured materials
o Use mediums for painting letters….
• Develop body-in-space concepts
• Pair children with one child can model the desired behavior in motor and visual activities.
• Kinesthetic activities:
o During story time, give a child a prop that relates to the story
o Provide letter cubes to make words
o Use glue letters
intervention - elementary school
• Begin at the level of the “Visual Hierarchy” where the child is experiencing difficulty (think about the visual pyramid)
• Reduce visually distracting and competing information in the environment
o Reduce glare by excluding glossy paper, shiny table surfaces
o use high interest material to improve visual perceptual skills
• Make the classroom environment less “busy”
• Use study carrels if child needs to reduce visual stimulation to focus and be attentive
o How do we do this without segregating the child???
• Work on child’s positioning to assure the child has a stable postural base in which to focus and attend
o Use bolsters, add seat backs, make sure child’s feet are weightbearing onto the floor or a stool/block
• Encourage different positions for visual activities. Each position should place child in a good alignment an offer adequate postural support.
• The child may benefit from color coded worksheet to assist him/her in attending to what visually goes together.make sure child is not color-blind
• Use kinesthetic approach
o Play games like Boggle, Scrabble
o Encourage child to participate actively while they read by writing while reading, underlining key words or placing an asterisk next to key words
treatment for visual attention
• Provide sensory based activities before and after activities that require visual attention
• Try to use activities that are intrinsically motivating to students to help the child maintain attention to task.
• Reduce extraneous environmental stimulation
• Integrate the tactile sense with visual activities to help with eye-hand coordination and attention
• Compensate for poor visual attention:
o Cover the entire page of a worksheet except for the activity or part on which the child is working, use a solid black sheet to cover 1 line at a time.
o Reduce competing auditory and visual stimuli – have child wear earplugs or headphones
o Use pastel colored paper to reduce glare
o Use color by marking or circling the specific work on a sheet that needs to be completed by the child.
treatment for visual memory
- Child will need repeated, consistent experiences
- Work with families and teacher to repeat activities at home and school
- Group information in a way that will provide retrieval cues and help child remember information
- “Chunking” – organizing information into smaller units
- “Maintenance rehearsal” – repetition, helps short term memory, but may have no long term effect (ie. repeating a phone number…)
- “Elaborative rehearsal” - relate new information to knowledge already stored in long-term memory
- Mnemonic devices – use of songs, rhymes, or acronyms
- Help the child notice differences in visual stimuli to promote storage of information into memory
- Play games such as concentration, the “what’s missing” game
- Start with short simple tasks and gradually reduce the complexity as the child becomes more successful
treatment for visual discrimination/figure ground
• use task analysis to design an intervention program, grade the activity from simple to complex
• help child identify and attend to the most relevant stimuli
• Teach children to visually scan and attend to the identifying features of objects or forms
• Teach children to visually scan or search picture (left to right, top to bottom)
• Use magazine pictures, remove a part, have child find
what is missing”
• Reorganize the child’s worksheets with color coding of sections that are important
• Worksheets can be cut-up and reorganized
• Gradually fade-out the restructuring as the child becomes more successful so the child can return to regular class work
• If child is having difficulty copying from the board, reduce clutter on chalkboard. Use colored chalk for high relevance items
• Reduce the amount of print on a page, number of math problems on a page
