Visual Perception Flashcards
Visual Perception
ability to interpret and give meaning to what one is seeing
Neurobehavioral Dysfunction
related to the errors people make during performance
Perceptual Problems
- Apraxia
- Visual discrimination/ visual-spatial perception
- Agnosia
- Unilateral Inattention (Neglect)
Apraxia
- Disorder of purposeful skilled movement that cannot be attributed to sensorimotor dysfunction. - This is not visual perceptual problem but a neurobehavioral dysfunction that can present similarly to perceptual deficits
- think old people post strokes not kids
Ideational Apraxia
- Ideational apraxia
- left frontal lobe or L MCA stroke
- Loss ability to conceptualize, plan and execute motor actions
- Involved in use of tools or objects
- Client doesn’t appear to know what to do with ADL items presented for task
- Client doesn’t demonstrate appropriate use of ADL items
- Client utilizes body parts in place of tools during ADL tasks (e.g. comb hair with fingers when comb/brush available)
Ideo-Motor Apraxia
- R/L frontal lobe – MCA
- Loss of access to kinesthetic memory so that purposeful movement cannot be produced, even though the idea is understood
- Uses clumsy inflexible movements that lack goal directed sequencing to hold ADL items
- Unable to change position of an ADL item in order to reorient it and cross the body’s midline, has difficulty gesturing the correct use of a familiar object after verbal command, in absence of object
- If you provide visual input and people are able to use these strategies, it is not a motor apraxia
Visual discrimination/visual-spatial perception
- R Parietal Lobe Damage
- awareness of the distinctive features of forms, including shape, orientation, size and color
- Figure-ground
- Form constancy
- spatial relations
- topographical disorientation
- depth perception (stereopsis)
- visual closure
Figure-Ground
- problems differentiating foreground from background.
- Ex: unable to locate scissors in cluttered drawer
- Ex: difficulty locating clothing on same colored sheets
Form Constancy
- ability to distinguish different types of forms in the environment, despite different size, shape, orientation, etc
Spatial Relation
- difficulty perceiving self or objects in relation to other objects with concepts such as up/down/, in/out, over/under, on/off.
- E.g. wearing pants inside out, or difficulty putting a jigsaw puzzle together.
Topographical Disorientation
- inability to find one’s way from one place to another.
- Ex: unable to master navigation of an unfamiliar unit, wandering, ending in the wrong room
Depth Perception (Stereopsis)
- inability to judge depths and distances.
- E.g. misjudging distance when placing toothbrush under running water or unable to determine how and when to step off escalator
Visual Closure
- inability to determine what the image is without having all of the details present.
- E.g. cannot determine what leftovers are in the back of the fridge
Agnosia
- R parietal lobe damage
- impaired ability to recognize the significance and/or differentiate between sensory stimuli
- inability to recognize objects, faces, limitations etc., despite intact cognition, language skills and visual acuity or field
- multiple forms - do not have more than one at a time usually
Auditory Agnosia
- unable to differentiate sounds
- Nothing to do with hearing, just the perception of the auditory processing
- Can’t differentiate between voices
- Visual Agnosia
- Tactile Agnosia
- Body Agnosia
- Visual or object: unable to differentiate objects
- Tactile: unable to differentiate objects by touch
- Body: difficulty recognizing own body parts
Anosognosia
- severe form of neglect in which client fails to recognize the presence or severity of paralysis
- Denial of deficits is a huge source of concern (safety)
Prosopagnosia
- unable to recognize faces, including loved ones or people they have met numerous times
Assessments Considerations Before Testing Visual Perception
before testing for visual perception make sure the person has attention, vision, understands directions (aphasia vs. perception); person has motor ability, if motor response is needed (paralysis vs. perception)
Non-Standardized Assessments
- Top down: skilled observation during functional tasks
- Bottom Up: informally ask to draw a clock, pen and paper task
Standardized Assessments
- Top Down: QoL, ADL measures, ACS, A-ONE
- Bottom UP:
- – VMI
- – MVPT
- – DTVP
- – Hooper
- – LOTCA, LOTCA-G, DOTCA-Ch
- – Test of Visual Perceptual Skills
- – SIPT
- – Rivermead Behavioral Memory Test
Hooper Visual Organization Test (VOT)
- measures ability to organize visual stimuli (screening)
- takes less than 15 min with scoring
- test book with pic and score sheet
- Normed on adolescents and adults
- Score: determine credit for each response (.5, 1, 1.5)
- Determine raw score for client then corrected score
Motor Free Visual Perception (MVPT)
- Measures visual perception without motor involvement (spatial relationships, visual discrimination, figure-ground, visual closure etc.)
- 2-30 minutes to administer
- Visual perception test (book) and score sheet
- Normed on people age 4-95
- Scoring: tally raw score, use norms tables to convert to standard scores
Non-Standardized OT Assessment for Apraxia
-top down: skilled observation during functional tasks
• Bottom up: informally ask gesture 1-2 commands, select appropriate tool
Standardized Assessment for Apraxia
- Top Down: A-ONE, AMPS, Kettle Test
- Bottom Up: Cambridge Apraxia Battery, Limb Apraxia Test, Florida Apraxia Screening Test
A-ONE
- Standardized and structured observation of: feeding, bathing, dressing, hygiene, mobility, communication
- Evaluates: apraxia, neglect, spatial relations, perseveration, topographic disorientation, agnosias, etc.
- Requires a 5-day training course
