Processing Speed Index (PSI) Flashcards

An examinee completes the WAIS-IV. Their performance on the Processing Speed Index (PSI) is significantly lower than their scores on the Verbal Comprehension Index (VCI) and Perceptual Reasoning Index (PRI). During the administration of the Coding subtest, the examiner notes the individual has considerable difficulty with graphomotor control, and their pencil grip appears awkward and inefficient. Which statement is the most accurate interpretation?

Answer: The observed fine-motor difficulties may have suppressed the PSI score, suggesting it may not be a pure measure of cognitive speed for this individual.

The Processing Speed Index, particularly the Coding subtest, requires rapid and precise visual-motor coordination. Significant difficulties with graphomotor skills can hinder performance, making it unclear if the low score is due to slow cognitive processing, slow motor output, or both. Therefore, the score may be an underestimate of the individual's actual cognitive processing speed.

Which combination of core subtests on the WAIS-IV is used to calculate the Processing Speed Index (PSI)?

Answer: Coding and Symbol Search

The Processing Speed Index (PSI) on the WAIS-IV is derived from the scaled scores of two core subtests: Coding and Symbol Search. These subtests measure the speed and accuracy of visual identification, decision-making, and decision implementation.

The Processing Speed Index (PSI) is considered a measure of an individual's ability to:

Answer: Quickly and accurately scan, discriminate, and sequence simple visual information.

The PSI assesses the ability to efficiently and accurately process simple or routine visual information under timed conditions. It involves skills such as visual scanning, discrimination, short-term visual memory, and visuomotor coordination.

A psychologist is evaluating a 70-year-old client who has recently recovered from a minor stroke. The client's verbal abilities seem intact, but they report 'thinking slower' than before. On the WAIS-IV, which of the following patterns would be most consistent with this presentation?

Answer: A PSI score that is significantly lower than their Verbal Comprehension Index (VCI) score.

Processing speed is known to be sensitive to various neurological conditions, including stroke. A common finding is a decline in the speed of information processing, which would be directly reflected in a lower PSI score. A discrepancy where the PSI is significantly lower than the VCI, which measures more crystallized and less speed-dependent verbal abilities, is a classic pattern in such cases.

Which of the following is LEAST likely to be a primary cognitive skill measured by the Symbol Search subtest of the PSI?

Answer: Verbal abstract reasoning

Symbol Search requires the examinee to quickly scan a search group of symbols and determine if a target symbol is present. This task relies heavily on visual scanning, discrimination, decision-making speed, and sustained attention. Verbal abstract reasoning, the ability to understand and work with abstract verbal concepts, is a primary function of the Verbal Comprehension Index (VCI), not the PSI.

When interpreting the WAIS-IV results, the General Ability Index (GAI) is sometimes used instead of the Full Scale IQ (FSIQ). The GAI is calculated to provide an estimate of general intelligence that is less influenced by which two indices?

Answer: Working Memory and Processing Speed

The General Ability Index (GAI) is derived from the core subtests of the Verbal Comprehension Index (VCI) and the Perceptual Reasoning Index (PRI). It is intentionally calculated to minimize the influence of cognitive abilities that are more vulnerable to impairment, specifically working memory and processing speed. This makes the GAI a useful score when an individual's performance may be unduly affected by attention, concentration, or processing speed deficits.