Wechsler FSIQ and Index Score Interpretation Flashcards

A psychologist evaluates a child who obtains a Full Scale IQ (FSIQ) of 92 and a General Ability Index (GAI) of 108. Which of the following is the most likely interpretation of this score pattern?

Answer: The child has a relative weakness in cognitive abilities measured by the Working Memory and/or Processing Speed indices.

The GAI is derived from the Verbal Comprehension and Visual Spatial/Fluid Reasoning subtests, which are less sensitive to attention and processing speed. The FSIQ includes the Working Memory Index (WMI) and Processing Speed Index (PSI). A significantly higher GAI than FSIQ suggests that lower scores on working memory and/or processing speed tasks are pulling down the overall FSIQ score, indicating a relative weakness in those areas of cognitive proficiency.

Under which circumstance is the Full Scale IQ (FSIQ) considered the most interpretable and valid summary of an individual's general intellectual ability?

Answer: When there is minimal variability and no statistically significant, unusual discrepancies among the primary index scores.

The FSIQ is most meaningful as a single summary score when the underlying index scores (e.g., VCI, VSI, FRI, WMI, PSI) are relatively consistent. Significant variability between the indices suggests that cognitive abilities are not developing evenly, and a single FSIQ score may mask important cognitive strengths and weaknesses. In such cases, interpreting the profile at the index level is more informative.

An evaluation of an adult client using the WAIS-IV reveals the following index scores: Verbal Comprehension Index (VCI) = 118, Perceptual Reasoning Index (PRI) = 115, Working Memory Index (WMI) = 88, and Processing Speed Index (PSI) = 85. Which statement best describes this client's cognitive profile?

Answer: The client shows well-developed verbal and non-verbal reasoning skills but may struggle with tasks requiring mental manipulation of information and rapid visual scanning.

The VCI (118) and PRI (115) are in the High Average range, indicating strong verbal and perceptual reasoning skills. The WMI (88) and PSI (85) are in the Low Average range. This pattern points to a relative weakness in cognitive proficiency—specifically, working memory (mentally holding and manipulating information) and processing speed (quickly and accurately scanning visual information).

When an examiner finds a 20-point difference between a client's Verbal Comprehension Index (VCI) and Processing Speed Index (PSI), why is it crucial to consult base rate tables in the test manual?

Answer: To determine how frequently a discrepancy of that magnitude occurred in the normative sample, which informs its clinical significance.

A statistically significant difference between scores simply means it is unlikely to be due to chance. However, some large differences are relatively common in the general population. Consulting base rate tables reveals the percentage of the normative sample that obtained the same or a greater score difference. A discrepancy that is both statistically significant and rare (has a low base rate) is considered more clinically meaningful.

A 15-year-old is administered the WISC-V and obtains a Full Scale IQ (FSIQ) of 88, with a 95% confidence interval of 82-94. This FSIQ score corresponds to the 21st percentile. Which is the most accurate and complete interpretation of these results?

Answer: We can be 95% confident that the adolescent's true FSIQ falls within the Low Average range, and their overall performance exceeds that of approximately 21% of their same-age peers.

An FSIQ of 88 is classified as Low Average (scores 80-89). The 95% confidence interval (82-94) indicates the range where the individual's true score likely falls. The 21st percentile means the individual scored as well as or better than 21% of peers in the normative sample. This statement correctly synthesizes all three pieces of information: the classification, the meaning of the confidence interval, and the definition of the percentile rank.

Which of the following best describes the Full Scale IQ (FSIQ) as derived from the Wechsler intelligence scales?

Answer: A comprehensive score that represents an individual's current overall level of general cognitive and intellectual functioning.

The FSIQ is a composite score derived from subtests that measure a wide range of cognitive abilities, including verbal comprehension, visual-spatial reasoning, fluid reasoning, working memory, and processing speed. It is intended to provide a summary of an individual's current overall (or 'global') intellectual functioning compared to their same-age peers.