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Chapter 6

PSY100H1 Chapter Notes - Chapter 6: Pathognomonicity, Neuropsychological Assessment, Neuropsychological Test

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Pare, Dwayne

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PSYC31 Chapter 6: The Neuropsychological Examination: Interpretation
The Nature of Neuropsychological Examination Data
The basic data of psychological examinations are behavioral observations
Different Kinds of Examination Data
Background Data
o Essential for providing the context in which current observations can be best
o Requires knowledge of developmental and medical history, family background,
educational and occupational accomplishments, and the patient’s current living
situation and level of social functioning
o Sensory and motor status, alertness cycles and fatigability, medication regimen, and
likelihood of drug or alcohol dependency
o Contributions of background variables have not always been appreciated in the
interpretation of many different kinds of tests
Behavioral Observations
o Naturalistic observations can provide very useful info about how the patient functions
outside the formalized examination setting
o Value of naturalistic observations may be most evident when formal examination
findings alone would lead to conclusions that patients are more or less capable than
they actually are
o Behavioral characteristics that compromise their adequate and sometimes even
excellent cognitive skills are not elicited in the usual neuropsychiatric or
neuropsychological examination
o How patients conduct themselves in the course of the examination is another source of
useful info
Test Data
o Testing differs from other sources of psychological data gathering in that it elicits
behavior samples in a standardized, replicable, and more or less artificial and restrictive
o Strengths: sameness of the test situation for each subject, the sameness that enables
the examiner to compare behavior samples between individuals
o Weakness: psychological test observations are limited to the behaviors prompted by the
test situation
o Psychological examination extrapolates from a limited set of observations to the
patient’s behavior in real-life situations
o Extrapolations are likely to be as accurate as the observations on which they are based
are pertinent, precise, and comprehensive, as the situations are similar and as the
generalizations are apt.
o Examiners rely on their common sense judgments and practical experiences in making
test-based predictions about their patient’s real-life functioning
Quantitative and Qualitative Data
Every psychological observation can be expressed either numerically as quantitative data or
descriptively as qualitative data
2 different approaches to neuropsychological assessment
An actuarial system exemplifies the quantitative method. It relies on scores, derived indices, and
score relationships for diagnostic predictions
Clinical approach is built upon richly described observations without objective standardization.
These clinicians document their observations in careful detail
Conditions necessary for actuarial predictions to be more accurate than clinical ones
o There be only a small number of probable outcomes
o Prediction variables be known
o Data from which formula was derived be relevant to the questions asked
Actuarial evaluations overlook the realities of neuropsychological practice in an era of advanced
neuroimaging and medical technology
Fixed versus flexible approaches
Quantitative data
o Scores are summary statements about observed behavior
o Scorer evaluates each behavior sample to see how well it fits a predetermined category
and then it gives it a place on a numerical scale
o Scored tests with more than one item produce a summary score that is the simple sum
of the scores for all the individual items
o Final test scores may misinterpret the behavior under examination on 2 counts:
It’s based on a narrowly defined aspect of a set of behavior samples and it’s 2 or
more steps removed from the original behavior
Global or full scale scores calculated by summing or averaging a set of test
scores are 3-4 steps removed from the behavior they represent
o Standard scoring systems provide the means for reducing a vast array of different
behaviors to a single numerical system
This enables the examiner to compare the score of any one test performance of
a patient with all other scores of that patient or with any group or performance
Problems in the Evaluation of Quantitative Data
o It is important to keep in mind the abstract and artificial nature when interpreting test
o Reification of test scores can cause the examiner to overlook or discount direct
o A test score approach to psychological assessment that minimizes the importance of
qualitative data can result in serious distortions in the interpretations, conclusions, and
recommendations drawn from such a one-sided data base
o To be neuropsychologically meaningful, a test score should represent as few kinds of
behavior or dimensions of cognitive functions as possible
o It is often difficult to know what functions contribute to a score obtained on a complex,
multidimensional test task without appropriate evaluation based on search for
commonalities in patients’ performance on different tests
o If a score is over-inclusive it becomes virtually impossible to know just what behavioral
or cognitive characteristic it represents
o Range of observations an examiner can make is restricted by the test
o Multiple-choice and automated tests offer no behavior alternatives beyond the
prescribed set of responses
o For most paper-and-pencil or automated tests, how the patient solves the problem or
goes about answering the question remains unknown or is, at best, a matter of
conjecture based on such relatively insubstantial info as heaviness or neatness of pencil
marks, test-taking errors, patterns or nonresponse, erasures, and the occasional pencil-
sketched spelling tryout or arithmetic computations in the margin
o The fine-grained scaling provided by the most sophisticated instruments for measuring
cognitive competence is not suited to the assessment of many of the behavioral
symptoms of cerebral neuropathology
o Behavioral aberrations due to brain dysfunction can be so highly individualized and
specific to the associated lesion that their distribution in the population at large, or even
in the brain impaired population, does not lend itself to actuarial prediction techniques
o Evaluation of test scores in the context of direct observations is essential when doing
neuropsychological assessment
o Different individuals may obtain the same test score on a particular test for very
different reasons
o What a test actually is measuring may not be what its name suggests or what the test
maker has claimed for it
Qualitative data
o Direct observations
o Observations of the person’s test taking behavior as well as test behavior per se
o Observations of patients’ appearance, verbalizations, gestures, tone of voice, mood and
affect, personal concerns, habits, and idiosyncrasies can provide a great deal of info
o Observations of patients’ reactions to the examination itself
o Observations of the manner in which they handle test material, the wording of test
responses, the nature and consistency of error and successes, fluctuations in attention
and perseverance, emotional state, and the quality of performance form moment to
moment as they interact with the examiner and with the different kinds of test material
are the qualitative data of the test performance itself
Limitations of qualitative data
o Distortion or misinterpretation of info obtained by direct observation results from
different kinds of methodological and examination problems
o All of the standardization, reliability, and validity problems inherent in the collection
and evaluation of data by a single observer are ever-present threats to objectivity
o When the patient’s communication skills are questionable, examiners can never be
certain that they have understood their transactions with the patient
o The communication disability may be so subtle and well masked by the patient that the
examiner is not aware of communication slips
o Some patients may be entirely or variably uncooperative, many times quite
o Clinicians gain experience with many patients from different backgrounds, they are
increasingly able to estimate or at least anticipate the subtle deficits that show up as
lowered scores on tests