Perception and Construction Abilities

The ability to perceive stimuli is one of the basic requirements for the assessment of cognitive function. Therefore, tests of visual, auditory, and tactile perception are common in neuropsychological assessments. Certain alterations in perception, such as neglect, are diagnostically informative.

VISUAL PERCEPTION AND CONSTRUCTION

Tests of visual perception typically assess color perception, object recognition, visual organizational abilities, visual scanning, and differentiation of figure from ground. Most neuropsychological assessments will assess color perception informally. The Color Vision Screening Inventory y is occasionally used by examiners, however. This test provides a screening measure of color blindness.

Peabody Picture Vocabulary Test-Revised.y This test is discussed in the section on Tests of Verbal Function; it can be used to assess ability to visually recognize objects.

Benton Facial Recognition Test.y This test of visual object recognition uses faces as stimuli. Patients are presented with a target face on one page and six faces on the adjacent page. One of the six faces matches the target face. The test progresses in difficulty from easy (a duplicate of the target face is presented in the six faces) to hard (the matching face differs from the target face in orientation and lighting). Since both the target and matching face are seen together, memory requirements are minimized.

Judgment of Line Orientation (JLO). y This test assesses ability to match lines of different orientation to target lines. Difficulty increases on this test by varying the length of the matching lines. Since both target and matching lines are seen together, memory requirements are minimized.

Hooper Visual Organization Test (HVOT). y This test presents the patient with 30 easily recognized objects that have been decomposed into parts and randomized. The patient is required to identify each object. Successful performance on this test requires the patient to mentally reorganize the decomposed images into the complete shape. There have been a number of normative studies of performance on the HVOT, but none is fully adequate.

Picture Arrangement.y This subtest of the WAIS-R requires the patient to rearrange a series of pictures that, when placed in the correct order, tell a story. One advantage of this test is the extensive normative data generated for the WAIS-R.

Letter Cancellation Test.y This visual scanning test is discussed in the section on Tests of Attention and Vigilance. When systematic errors occur on this test, such that the patient completes only one side of the page, the possibility of visual neglect is raised.

Line Bisection Test.y This test presents the patient with lines drawn in different locations on a page. The patient is required to draw a perpendicular line through the lines on the page. Visual scanning is required to locate all the lines on the page. As with the cancellation tests, if systematic errors occur, where the patient does not bisect the line on one side of the page, the possibility of visual neglect is raised.

Embedded Figures Test. y This test differentiates figure from ground and consists of 16 line drawings of figures on one page, and a complex figure that contains the target figure and overlapping figures. The patient is required to trace the target figure in the complex figure. Scoring is on a pass-fail basis, with extra credit given for fast performance.

Rey-Osterrieth Complex Figure.y This test of visual construction is discussed in the section on Memory. Information on visual construction can be found from performance on the copy portion of this test.

Clock Drawing Test.y This test of visual construction in which the patient is required to draw a clock with all the numbers and "set" the clock at 20 minutes to four o'clock. Clock drawing has been a part of bedside mental status testing for a long time, but scoring had been somewhat arbitrary. The addition of explicit scoring criteria has improved interpretation.

Developmental Test of Visual-Motor Integration (VMI). y This visual construction test was originally developed for the assessment of children. It is also useful in assessing adult visual constructional abilities, however. The patient is required to copy 24 geometric designs ranging from simple (a single line) to complex. Adequate norms for children exist for this test, and its range of performance can be extended to adults.

Three-Dimensional Block Construction.y This test assesses constructional abilities in three dimensions. Patients are presented with 29 blocks of different shapes in a prearranged order. A model is shown to the patient, who is told to use some or all of the blocks to re-create the model. In all, three models are presented to the patient. A maximum of 5 minutes is allowed to complete each model. Adequate norms exist for this test.

AUDITORY PERCEPTION

Auditory perception is tested for acuity, perception of organized sounds, and rhythms.

Sensory Examination.y This test is part of the Halstead-Reitan Battery and assesses auditory perception to single and simultaneous stimulations. The examiner stands behind the patient and gently rubs two fingers together next to each ear. This tests auditory perceptual problems in each ear, and also the presence of extinction to double- simultaneous stimulation.

Speech-Sound Perception Test.y This test is part of the Halstead-Reitan Battery. Patients listen to 60 nonsense syllables on a tape and must choose among four options of printed versions of the sounds. One problem with this test is that individuals who have high-frequency hearing loss tend to perform poorly.

Seashore Rhythm Test.y This test is part of the Halstead-Reitan Battery. Patients listen to two sets of tape- recorded rhythms and are required to judge whether the rhythms are the same or different. The test includes easy items with a few beats and complex items with many beats. Because the patient must remember the first rhythm and must attend to rapidly changing stimuli, this test also measures memory and attention.

TACTILE ABILITIES

Testing of tactile abilities in most neuropsychological assessments is limited to the hands. This information is particularly important for assessing the effects of tactile deficits on test performance.

Sensory Examination.1^ This test is part of the Halstead-Reitan Battery. The tactile ability assessment includes Fingertip Number Writing, where the examiner traces a number on each finger and asks the patient to report the number without visual guidance, and Tactile Finger Recognition (discussed in the section on Tests of Attention and Vigilance), where the patient must identify which finger has been touched by the examiner without visual guidance.

Face-Hand Test.y , y This is a test of single and simultaneous stimuli on either side of the patient's hand, face, or both. Information from this test is helpful in identifying the presence of tactile inattention.

Tactile Form Perception. y This test requires the patient to recognize geometric forms placed in one hand hidden from view, and identify a drawing of the object in a multiple-choice format. Adequate norms are provided for this test. A variant of this test is found in the Halstead- Reitan Battery, which uses three-dimensional forms and requests verbal responses as opposed to multiple-choice responses.

CLINICAL SITUATIONS FOR TESTS OF PERCEPTION AND CONSTRUCTION ABILITIES

Assessment of perception and construction abilities is very important, not only to aid in diagnosis of inattention (neglect) and constructional apraxia, but also to assess the competency of basic skills required for adequate testing. Most of the tests presented also can assess attention and vigilance. Testing is appropriate for all patients except perhaps for those with alterations in level of consciousness (see Chapter.! ), or dementia (see Chapter.33 ).

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