What does a cognitive assessment actually tell you about a child?
Updated: Aug 25
In brief
A cognitive assessment looks at how a child thinks and reasons, not just at one IQ number.
It can show strengths and differences across areas such as verbal reasoning, visual-spatial skills, fluid reasoning, working memory and processing speed.
The Full-Scale IQ can be useful, but it may not tell the whole story when a child has a very uneven profile.
Other scores, such as the General Ability Index (GAI), can sometimes give useful additional information about reasoning ability.
An uneven profile is not a diagnosis, but it can help explain why a child performs very differently across tasks or settings.
Scores are interpreted alongside observations, developmental history, language background and information from home and school.
A cognitive assessment cannot measure everything important about a child, including creativity, motivation, wellbeing or future potential.
A learning profile, which also looks at attainment, can help show whether a child’s reading, writing or maths are developing in line with their cognitive strengths.
The most useful outcome is not the highest score, but a clearer understanding of the child’s strengths, barriers to learning and appropriate next steps.
A cognitive assessment can provide valuable information about how a child thinks, reasons, remembers and processes information. However, it is not simply an “IQ test”, and the most useful information is often found beyond the overall IQ score
A good assessment looks at the pattern of strengths and differences across different areas of thinking, alongside what is known about the child from home, school and the assessment session itself.
What does a cognitive assessment measure?
Cognitive assessments compare a child’s performance with that of other children of a similar age on a carefully standardised set of tasks.
For example, the WPPSI-IV UK, used with younger children, and the WISC-V UK, used with school-aged children, are in-depth assessments that include several areas of cognitive functioning.
Depending on the child’s age and the assessment used, these can include:
verbal comprehension, such as understanding and expressing verbal concepts
visual-spatial reasoning, such as analysing and constructing visual patterns
fluid reasoning, which involves identifying relationships and solving unfamiliar problems
working memory, the ability to hold and work with information for a short period
processing speed, which looks at how quickly and accurately a child can process relatively simple visual information.
The WISC-V UK, for example, provides separate index scores for Verbal Comprehension, Visual Spatial, Fluid Reasoning, Working Memory and Processing Speed, as well as a Full-Scale IQ.
The WPPSI-IV UK uses a similar structure but is simplified and adapted for younger children.
Why do the individual scores matter?
An overall IQ score can be useful, but it compresses performance across several different types of tasks into one number. Two children with the same Full-Scale IQ could have very different cognitive profiles:
One child might perform at a similar level across all areas.
Another might have exceptionally strong verbal and fluid reasoning alongside much lower working memory or processing speed.
The overall score alone would not show that difference clearly.
This is why we provide a written profile that looks closely at the individual index and subtest scores, the differences between them and whether those differences are unusual or meaningful for that particular child.
The pattern can sometimes help explain why a child appears highly capable in some circumstances but finds other tasks disproportionately difficult.
Is the Full-Scale IQ always the best description of ability?
Not necessarily.
The Full-Scale IQ, or FSIQ, is designed to provide an estimate of overall intellectual ability. For many children it is useful and representative. However, when there are substantial differences between cognitive areas, one overall number may tell only part of the story.
For example, a child may show very high verbal, visual-spatial and fluid reasoning but much lower working memory or processing speed. Their FSIQ incorporates performance across these areas, so it may be lower than their reasoning scores would suggest.
In situations like this, other scores can provide additional information. One example is the General Ability Index (GAI). The GAI draws more heavily on verbal, visual-spatial and fluid reasoning abilities and is less influenced by working memory and processing speed than the FSIQ.
This does not mean that the GAI is automatically a “better IQ score”, or that lower working memory and processing speed should simply be ignored. Quite the opposite. A meaningful difference between reasoning ability and cognitive efficiency may itself be important.
The aim is to understand the whole pattern, rather than choosing whichever number is highest.
What does an uneven cognitive profile mean?
An uneven profile simply means that a child performs considerably better in some cognitive areas than others. Some variation is normal. Very few people perform identically across every task.
What becomes more interesting is when the differences are substantial, unusual compared with children of the same age, or help explain something already being observed in everyday life. For example, a child might:
reason exceptionally well verbally but find timed visual tasks much harder
solve unfamiliar problems very effectively but struggle to hold several pieces of information in mind
perform much better on non-verbal tasks than on tasks requiring spoken language
show very advanced reasoning alongside much more ordinary cognitive efficiency.
An uneven profile is not a diagnosis. It does not, by itself, demonstrate ADHD, dyslexia, autism or any other condition. Similar score patterns can arise for many different reasons.
Instead, it provides information that needs to be considered alongside the child’s development, learning, behaviour and circumstances.
What can a cognitive assessment not tell you?
A cognitive assessment cannot tell us everything important about a child. It cannot directly measure:
creativity
curiosity
motivation
perseverance
emotional wellbeing
social understanding
interests and passions
the quality of teaching they have experienced
how appropriately challenged they are at school
what they will achieve in the future.
It also cannot diagnose most learning or neurodevelopmental conditions simply from the cognitive scores.
A cognitive assessment is therefore best thought of as one important source of evidence, rather than a complete description of the child.
Why do observations during the assessment matter?
Scores tell us what a child achieved on particular tasks. Observation can help us understand how they approached them.
During an assessment, we might notice:
whether the child understands instructions immediately or needs them repeated
whether they answer impulsively or work very carefully
how they respond when a task becomes difficult
whether they persist or give up quickly
whether they talk themselves through problems
whether attention varies across different types of tasks
whether timed tasks appear particularly demanding
whether they recognise and correct their own mistakes
whether their engagement changes when tasks become more challenging.
These observations should not be overinterpreted. A single assessment session is only one context. However, when they are considered alongside test scores and information from parents and school, they can help make sense of the pattern.
Why does background information matter?
The same score can mean different things in different children.
For example, a relatively low verbal score needs to be interpreted differently for a child who is learning English as an additional language or is bilingual, a child with a history of language difficulties and a child whose verbal reasoning at home appears exceptionally advanced.
Similarly, lower performance on a timed task might reflect processing speed, attention, motor demands, anxiety, unfamiliarity with the task or a combination of factors. This is why we consider information such as:
developmental history
language background
educational experience
parent observations
school information
previous assessments or diagnoses
areas of particular strength or difficulty
the reason the assessment was requested.
The purpose is not simply to generate scores. It is to understand what those scores mean for this particular child.
How do the findings translate into recommendations?
Assessment is most useful when it leads to a better understanding of what the child needs. Recommendations should therefore follow from the profile rather than being a generic list.
For one child, the important issue may be the need for substantially greater cognitive challenge. For another, strong reasoning may be accompanied by weaker working memory, so reducing unnecessary memory demands while continuing to provide intellectually demanding work may be important. Another child may need more opportunity to demonstrate knowledge verbally because written output does not yet reflect their thinking.
The aim is to connect the assessment findings with everyday questions such as:
What level of challenge is appropriate?
What helps this child learn efficiently?
Are particular task demands getting in the way?
Are their strengths being sufficiently developed?
What adjustments or teaching approaches might help?
Does anything need further investigation?
When can a learning profile add useful information?
A cognitive assessment tells us about aspects of how a child thinks. It does not directly tell us how well they currently read, write or use mathematics. This is where our Learning Profile, which includes measures of attainment, can be particularly useful.
Comparing cognitive abilities with attainment can help identify patterns that would otherwise be difficult to see. For example, a child may have very high verbal reasoning but much weaker reading or spelling than would be expected from that level of ability.
Another may have mathematical attainment that appears average for their age but is unexpectedly low compared with exceptionally strong quantitative reasoning. Conversely, attainment may be very advanced and broadly consistent with the child’s cognitive profile.
The WISC-V UK was specifically developed to support comparison between cognitive and attainment measures, including links with the WIAT-III UK.
Looking at both can therefore help answer a slightly different question:
Is this child achieving in line with what their cognitive profile suggests they may be capable of?
Looking at the whole child
The most useful cognitive assessment is not the one that produces the most impressive number. It is the one that helps explain the child more clearly. That means considering:
the Full-Scale IQ
individual index and subtest scores
alternative composite scores where appropriate
significant strengths and differences within the profile
observations during assessment
developmental and educational history
information from parents and school
attainment, where this is relevant
the child’s actual experience of learning.
The numbers provide important evidence, but interpretation is what turns those numbers into something useful.
If you would like to understand more about what our assessments include and the information they can provide, see our Assessments Page.
Sources and further reading
Davidson Institute for Talent Development (2008) Testing Your Gifted Child: A Springboard for Effective Advocacy.
Pearson Clinical UK, Pearson Clinical UK, WPPSI-IV UK: Wechsler Preschool and Primary Scale of Intelligence, Fourth UK Edition.
Pearson Clinical UK, WISC-V UK: Wechsler Intelligence Scale for Children, Fifth UK Edition.
