Processing Speed Index (PSI) Flashcards

Which of the following BEST describes what the Coding subtest measures within the PSI?

Answer: Psychomotor speed and visual-symbol association learning

Coding measures how quickly and accurately a person can copy symbols paired with numbers, tapping psychomotor speed and associative learning.

When interpreting a low PSI in a child transitioning to adult norms, the clinician should FIRST consider:

Answer: Whether the subtest scores within the PSI are consistent with each other

Checking subtest scatter within the PSI determines whether the composite is a valid summary of the domain.

A clinician suspects ADHD in an adult. Which PSI pattern would be MOST consistent with inattention rather than motor slowing?

Answer: Low Symbol Search but average Coding

Selectively low Symbol Search with preserved Coding suggests attentional scanning difficulties rather than generalized motor slowing.

The PSI composite is computed by summing scaled scores and converting to a standard score with mean 100 and SD of:

Answer: 15

Like all WAIS index scores, the PSI has a mean of 100 and a standard deviation of 15.

Traumatic brain injury (TBI) most consistently impairs which WAIS index first and most severely?

Answer: Processing Speed Index

TBI reliably and disproportionately reduces processing speed, making PSI the index most sensitive to acquired brain injury.

Which statistical concept explains why a very low PSI can lower the Full Scale IQ even when other indexes are average?

Answer: Composite averaging across indexes

The FSIQ averages contributions from all four indexes, so a depressed PSI pulls the overall composite downward.

On the Coding subtest, what is the primary reason examinees are given a sample practice row before the timed portion?

Answer: To ensure the examinee understands the symbol-digit key before timing begins

The practice row ensures comprehension of the task so that the timed score reflects processing speed, not confusion about instructions.