Presentation on theme: "Visual Perception Assessment “The mind can only see what it is prepared to see” - Edward de Bono OCT 1172: Neuroanatomy Tuesday, February 1 st, 2005 Nadia."— Presentation transcript:
Visual Perception Assessment “The mind can only see what it is prepared to see” - Edward de Bono OCT 1172: Neuroanatomy Tuesday, February 1 st, 2005 Nadia Abdel-Hafez Lisa Purdy Vivien Chan
Agenda Overview of visual perception Theory Summary of: LOTCA Motor-Free Visual Perception Test Rivermead Perceptual Assessment Battery OSOT Perceptual Evaluation Application to occupational performance of meal preparation and driving
What is Visual Perception? Perception “the dynamic process of receiving the environment through sensory impulses & translating those impulses into meaning based on a previously developed understanding of that environment.” “the dynamic process of receiving the environment through sensory impulses & translating those impulses into meaning based on a previously developed understanding of that environment.” (Bouska et al., 1990; Grieve, 1993; Arnadottier, 1990) Visual Perception “ability to identify, organize, interpret and comprehend visual information received by a person through his or her eyes” “ability to identify, organize, interpret and comprehend visual information received by a person through his or her eyes” (Hammill et al, 1993)
How does visual processing occur? ~ Frame of Reference ~ Bottom-Up Processing Primary perceptual processes modify sensation into perception Environment driven –Example Sensation = vision, perception = form, colour, movement Sensation = vision, perception = form, colour, movement Top-Down Processing Learned experience of perceptions decrease number of possible interpretations of sensory environment Driven by knowledge set –Example Opitical illusions when told what to look for Zolton, 1996
Luria’s Functional Systems Model : Perceptual Process The CNS interprets Information in three stages: 1. Nervous System registers stimulus event Luria’s first functional unit 2. System interprets and organizes sensory information Luria’s second functional unit 3. System compares stimulus to past experience and relates stimulus to goal. Luria’s third functional unit All three stages work together and failure can occur at any stage. Abreu & Toglia, 1987
Second Functional Unit Posterior Cortex Sensation & Perception First Functional Unit Brain Stem Arousal & Activation Third Functional Unit Frontal Lobe Programming & Regulating Primary Area Zone Basic sensory Information Ie. light and angle sensations Secondary Area Zone Turning sensations into perceptions Unimodal Difficulties with this zone = Agnosia Ie. Light sensation is perceived as an object. Tertiary Area Zone Integration of all sensations Poly modal Integration of all sensations Ie. watching your favorite T.V. show favorite Luria’ s Functional Systems A process of perception
Why Assess Visual Perception? Mental Status examinations rely heavily on verbal skills which may not detect subtle cognitive impairments, which vision perception tests could identify. Golisz, K., Toglia, J., Cause of continued confusion and lack of rehabilitation progress despite return of motor function Zolton, 1996 May contribute to inability to perform desired occupations as well as occupations that are needed and/or expected
Visual Perception Barbara Zolton organizes components of visual perception into 3 catagories: 1.Visual Processing Registration of visual input through ocularmotor control, visual fields, and acuity 2.Visual Discrimination 3.Body Schema Representation of spatial relations among parts of body
LOTCA TM Battery Loewenstein Occupational Therapy Cognitive Assessment Authors: Malka Itzkovich, Betty Elazar, Sarah Averbach Developed in 1974, at the Loewenstein Rehabilitation Hospital in Israel
LOTCA: Purpose Determine client’s abilities and limitations in cognitive functioning Guides intervention Examines clinical change Screening tool for further assessment (Katz, Itzovich, Averbuch & Elazar, 1988)
LOTCA: Population Developed to assess patients with brain-injuries Validated to assess those 6 years and up Validated to assess those 6 years and up Lowenstein Occupational Therapy Cognitive Assessment-Geriatric (LOTCA-G) is also available
LOTCA: Approach Derived from: authors’ clinical experiences Luria’s neuropsychological model Piaget’s developmental model. Derivative of the Luria-Nebraska Neuropsychological Battery (LNNB) Bottom Up assessment
Luria: A Continuum of Perception According to Abreu, 1985: There are 6 areas critical for assessment: 1. Orientation 2. Attention 3. Motor Planning 4. Visual Processing 5. Cognition 6. Occupational Behaviour LOTCA’s domains are congruent with this theory.
Piaget’s Theory of Cognitive Developmental Model Age-level standards were developed by testing 240 healthy children (ages 6-12) for the determination: 1.Hierarchical order of acquiring the cognitive competencies included in test. 2.Age norms for subtests Developmental curves provided in manual (Averbach, 1989)
LOTCA: Subtests 1 & 2: Orientation Client is asked questions concerning : Time “what day is today?” Place “Name a city that is located near your home address” Orientation deficits are frequent symptoms of brain injuries. However, good orientation is not evidence of cognitive competence (Lezak, 1983) (Lezak, 1983)
LOTCA: Perception Six subtests: 3. Visual Identification of Objects 4. Visual Identification of Shapes 5. Overlapping Figures 6. Object Constancy 7. Spatial Perception 8. Praxis
Subtest 3: Visual Identification of Objects 8 everyday objects: chair, teapot, watch, shoe, bicycle, key, scissors, glasses are illustrated and presented to client Client is expected to name the objects correctly
What do you see?
Clients with Expressive Problems To rule out or control for anomia aphasia, the clinician shows the client two boards with four objects presented on each. Ask questions such as “Where is the chair?” What if you still could not see it?
Visual Identification of Objects If the client is unable to locate the 8 objects or has receptive aphasia, the therapist shows two boards with similar objects on each and the patient must match the target object on the board. If unable to complete that, the patient is shown two boards with identical objects and the patient can perform exact matching.
Subtest 4: Visual Identification of Shapes Patient is asked to identify 8 different shapes: square, triangle, circle, rectangle, diamond, semi-circle, trapezoid, hexagon. Two levels of difficulty If the client has expressive problems, they will be shown a board with identical shapes.
Detecting the Presence of Visual Agnosia Associative agnosia: unable to recognize the meaning of objects of what is being perceived The ability to see this object is intact, however, is not able to connect object with its meaning Able to copy and match
Detecting the Presence of Visual Agnosia Aperceptive agnosia: inability to visually perceive the object, therefore, unable to name the object Although, sensation and meaning are intact, there is a failure with visual perception Client will not be able to match and assessment will stop here if discovered
What is the LOTCA Missing? Other types of Agnosia’s are not assessed within the LOTCA…
Prosopagnosia Also called: associative and aperceptive face agnosia The inability to recognize an individual that is known to the client The client understands that he is looking at a face but cannot say to whom the face belongs (Zolton)
Colour agnosia Inability to recognize colours The patient cannot identify the colour the word is written in Diagrams in LOTCA are Black and White
Subtest 5: Overlapping Figures The evaluator shows the client two cards with three overlapping objects. Asks “what is drawn on the card?” Asks “what is drawn on the card?”
Subtest 5: Overlapping Figures This subtest assesses: Figure Ground Perception: The ability to distinguish foreground from background. (Zoltan, 1996)
Subtest 6: Object Constancy The clinician shows the patient four photographs of objects taken from unusual angles Asks patient “What do you see in the photograph?”
Subtest 6: Object Constancy If language difficulties are present, the clinician can use a multiple choice board
Subtest 6: Object Constancy Form Discrimination: The inability to distinguish between objects that are similar in form Colour, orientation, edge, and motion cues are all utilized for form discrimination Eg. difference between a “p” or “b” when reading
Subtest 7: Spatial Perception Patient is asked to discriminate between Right and left on himself Two objects: pencil and box Right and left of the therapist
Subtest 7: Spatial Perception This subtest assesses for Body Schema Disorders: Right/left discrimination- inability to tell left from right Somatognosia – lack of awareness of body structure and inability to recognize and reference one’s body parts
LOTCA: Remaining Areas Visual Motor Organization Thinking Operations These are concerned Higher Level Perception. Involves Construction Tasks Executive Functioning
LOTCA: Scoring Each subtest is scored on a 4-5 point scale 4 areas of LOTCA: 1. Orientation (max=8) 2. Perception (max=20) 3. Visuomotor organization (max=28) 4. Thinking operations (max=23) Attention and concentration is observed by therapist and is scored. Time is recorded. Attention and concentration is observed by therapist and is scored. Time is recorded. Each area can be interpreted separately Aids in treatment planning and intervention (Katz, 2002)
LOTCA: Psychometrics Psychometrically Sound Many studies have validated the test –Refer to Psychometric Chart in Handout Highlights –Can differentiate performance levels as well as between patterns of cognitive deficits related to the site of brain lesions (Katz et al, 1988). –Predictive and Ecological Validity with occupational performance in ADLs (Katz et al, 2000) (Katz et al, 2000)
LOTCA: Clinical Utility Client acceptability Includes procedures for aphasic patients Widely used and favored by occupational therapists Time: minutes, can be divided into 2-3 sessions if required minutes, can be divided into 2-3 sessions if required
LOTCA: Critique LOTCA’ s approach of cognition-perception assessment adheres to the criteria set forth by Abreu and Tonglia ( based on Luria’s theory) Hierarchical arrangement of tasks Flexible assessment e.g. Multi-choice format if needed Can observe the patient’s strategies in the visuomotor tasks.
Suggestions/Critique Inclusion of occupational behaviour is questionable Suggestions Vertical Placement of Diagrams to accommodate those with unilateral spatial neglect, as it could be a confounding factor. LOTCA relies heavily on visual/spatial abilities (Katz et al, 2000) Manual should have clearer definitions of constructs
Motor-Free Visual Perception Test (MVPT) Authors: Ronald P. Colarusso and Donald D. Hammill (1972)
MVPT Purpose Descriptive Measures visual perception without the variable of motor involvement Practical for screening, diagnostic and research purposes (Brown et al., 2003) (Brown et al., 2003)
Rationale behind “Motor Free” Motor free assessment of visual perception Colarusso and Hammill (1996) although motor and visual skills are often clearly associated, they can also be very separate abilities Authors claim many tests of visual perception require complicated graphic responses drawing introduces confounding variable of motor No clear rationale provided in manual as to why a motor free test of visual perception is desirable (Brown et al., 2003)
MVPT Approach Bottom up assessment 36 items, multiple choice format Inanimate pictures, black and white No time limit
MVPT Administration Administrator presents item to client, points to stimulus figure while verbalizing “look at this” Administrator points at 4 alternatives, while verbalizing “find it here” Administrator points at 4 alternatives, while verbalizing “find it here” Client points to one of four alternatives if cannot verbalize response Client points to one of four alternatives if cannot verbalize response Administrator confirms clients response Administrator confirms clients response
1. Visual Discrimination ability to discriminate dominant features in different objects
2.Visual Figure Ground Theory ability to distinguish an object from its background
3.Visual Memory ability to recall dominant features of one stimulus item or to remember the sequence of several items
Do you remember…
4. Visual Closure ability to identify incomplete figures when only fragments are presented
5.Visual Spatial Relationships ability to orient one’s body in space and to perceive the positions of objects in relation to oneself and to objects
MVPT Population Original MVPT Original MVPT - Colarusso and Hammill (1972) - standardized on 881 “normal” American children 4-8 years old, residing in 22 states - despite limited age range of normative data, MVPT used on children and adults due to good clinical utility (Brown et al., 2003) (Brown et al., 2003) MVPT Revised MVPT Revised - Bouska and Kwatny (1983) - original version revised and adapted for use with adult population - original MVPT administered to 32 patients with brain damage - analysis of data used in development of revision of original test (Bouska and Kwatny, 1983) (Bouska and Kwatny, 1983)
Additional Versions of MVPT MVPT Revised Colarusso and Hammill, 1993 addressed issues of outdated and incomplete normative data revised normative data collected on 912 children in Georgia and Northern California no psychometric studies completed on MVPT-R (Brown et al, 2003) MVPT Vertical To eliminate effect of unilateral neglect, items presented vertically, as opposed to horizontally Geared towards people 50 years and older (Mercier et al., 2001)
Scoring One raw overall score attained Usefulness of scoring method questionable Volpe-Johnstone (2001) too few items in some of the groupings to be able to make definitive statements regarding the domains Abreu and Toglia (1987) Dichotomous scores alone reveal little about the person’s functioning and should be eliminated guessing, inattention, perseveration and other brain-damage variables can affect score
Clinical Utility & Psychometrics Different versions available, enhances applicability Quick: 10 – 20 minutes Standardized: easy to administer and score Acceptability questionable Multi disciplinary Excellent validity and reliability (test-retest) Refer to handout
Suggestions/Critique Difficulty in interpreting results Dichotomous scoring (Brown et al, 2003) (Brown et al, 2003) Limited in intervention planning For predictive purposes, use in conjunction with ADL assessment Generalizability of MVPT questionable Clients’ who perform well on tests that assess visual processing of inanimate objects (as does MVPT), often perform poorly on tests that assess animate objects (Duchaine et al., 2003) (Duchaine et al., 2003)
Rivermead Perceptual Assessment Battery Authors: S. Whiting N. Lincoln G. Bhavnani J. Cockburn International Availability: Available worldwide
Rivermead, 1985 Purpose: – –16 subtests, screen for visual and spatial perception –Evaluative, descriptive, Psychometrics: –mixed results for predictablity (Donnelly, 2002) Clinical Utility: –No special training required, easy to administer –Standardized, with norms for ages 16-97
16 subtests assess within the following areas: Picture Matching Object Matching Size Recognition Series Missing Article Sequencing-Pictures Right/Left Copying Words Colour Matching Right/Left Copying Shapes Cube Copying Three-Dimensional Copying Cancellation Figure-Ground Discrimination Animal Halves Body-Image Self-Identification Body Image Reading Test Rivermead Perceptual Assessment Battery (RPAB) (Whiting, Lincoln, Bhavnani, & Cockburn, 1985) Critique: - Comprehensive, time consuming, and uses child-like material; - Need to increase difficulty level to avoid ceiling effect for patients less severely impaired (Chwen-Yng et al, 2000)
O.S.O.T. Perceptual Evaluation Marion Boys, Pat Fisher, and Claire Holzberg Ontario Society of Occupational Therapists, 1991 Purpose: – –Detection of perceptual impairment in adults using 18 tests – –Descriptive (screening tool), evaluative Psychometrics: – –high inter-rater reliability, established validity Clinical Utility: Population: patients with brain injury Oldest, popular (especially in stroke setting) Standardized: Very quick and easy to use Cancellation Sheets and the Score Sheets (copyright free)
Meal Preparation LOTCA TM Battery Visual Identification of Objects Agnosia unable to find/recognize any items used in meal prep (groceries, utensils, pots/pans) unless use other senses can use touch to identify objects, but safety issue (knife, stove)
Meal Preparation LOTCA TM Battery Visual Identification of Shapes Aperceptive Agnosia unable to “see” object (cannot describe, match, copy or discriminate from another object) will not be able to differentiate between shapes of items needed for cooking Cannot tell the difference between a spoon and a knife May reach for a round pizza pan instead of a rectangular cookie sheet
Meal Preparation Visual Identification of Shapes – Cont’d Associative Agnosia Would be able to describe difference between a fork and spoon, but not understand the meaning in difference between a fork and spoon could describe steam coming off a hot pot, but will not know it is steam or understand that it is hot and may therefore reach through it instead around it to turn off stove. cannot read recipes as letters have no meaning and cannot be interpreted by another sense (unless raised like brail) other than audition (have someone read directions to them, tape recorded recipes)
Meal Preparation LOTCA TM Battery Overlapping Figures trying to pick out utensils from a messy drawer, could use touch, but safety issue Messy spice cabinet, must sort though spice bottles to find the one you want Washing dishes in sink, could not see the plate underneath the pan in the sink
Meal Preparation LOTCA TM Battery Object Constancy Stacked pots and pans May not be able to recognize the pot because of different view when stacked May not be able to pick out produce from fridge Eg. Tomato cut in half, may not recognize that it is a tomato because seeing it from a different view (inside now exposed instead of seeing a perfectly round tomato)
Meal Preparation LOTCA TM Battery Spatial Perception Visual Spatial Agnosia Stereopsis would have difficulty pouring a liquid into a glass or pot, judgment of fullness impaired therefore = overfill Difficulty judging distances May try to place something on counter-top, undershoot and drop it on the ground, OR may knock things over (overshoot) NOTE: The LOTCA does not directly assess depth perception, does so Indirectly though visuomotor subtests
Driving Ability Motor-Free Visual Perceptual Test “…90% of informational input to the driver is visual.” “…visual perceptual skills such as scanning, tracking & figure ground discrimination determine the ability to notice and react to objects in the visual field.” Poor performance on the MVPT was found to be highly predictive of failure on the on-road driving test, but was not highly predictive of a pass Poor performance on the MVPT was found to be highly predictive of failure on the on-road driving test, but was not highly predictive of a pass Those with a score of 30 were 8.7x’s more likely to fail, than those with scores 30 Even at the highest scores, half the subjects passed while the other half failed Mazer, Korner-Bitendsky & Sofer, 1998
Driving Ability Motor-Free Visual Perceptual Test Visual Discrimination Shape: could not distinguish an object by shape (eg. Stop sign is an octagon), could not read road signs (“ambulance” in rear-view mirror), what about traffic lights that have extra arrows? Form: What is this? Can you recognize the major distinguishing features of this object? Colour Agnosia: traffic lights, especially when not in ONT Eg. Lights are vertical in ONT so know order of lights, but if drive into Quebec, lights are horizontal, and would not be able to distinguish Quebec, lights are horizontal, and would not be able to distinguish between red, yellow, and green between red, yellow, and green Note: MVPT does not test for colour discrimination and limited testing for letter discimination
Driving Ability Motor-Free Visual Perceptual Test Visual Figure Ground Can you find the traffic lights from the competing background? When approaching an intersection, you look for traffic lights to guide your next move (stop or go). Driving behind a car, can you distinguish the break lights from the other features of the vehicle? How about when it is snowing?
Driving Ability Motor-Free Visual Perceptual Test Visual Memory Changing lanes: –Must look in mirrors and check blind spot and remember where the cars are to change lanes When driving in rain or snow, lose vision for a brief moment as the wipers clear the windshield –Need to remember what was ahead of you Note: MVPT does not assess topographical orientation or sequencing, both are important abilities to have when driving Do you remember where the cars surrounding you are?
Driving Ability Motor-Free Visual Perceptual Test Visual Closure See part of a car in front of you Snow covered cars Tree that partially covers a sign
Driving Ability Motor-Free Visual Perceptual Test Visual Spatial Relationships NOTE: MVPT does not test for person to object relationships, only object to object; does not test distance between objects, only orientation; does not test animated object relationships, only inanimate objects. If you were driving into a wooded area with many trees and saw one had fallen on the road, would you be able to see that it was out of place (and avoid it?) If you were driving into a wooded area with many trees and saw one had fallen on the road, would you be able to see that it was out of place (and avoid it?) Ability to tell your distance from the intersection so that you know when to start breaking Ability to tell your distance from the intersection so that you know when to start breaking Parking Parking
Did you find all the faces?
Thanks for Listening! All replications of diagrams from original assessments