What does an IQ score mean, why is 100 average, and how should index scores and confidence intervals be read? A plain guide to interpreting an IQ report.
When the report reaches you, your eye first searches for the biggest number: "Full Scale IQ: 108." Below it there are a few more lines: Verbal Comprehension 121, Working Memory 86, Processing Speed 82. There is also something called a "confidence interval". Is 108 good or bad? Why is your daughter's verbal score so high when the others are low? Will it be enough for BİLSEM (Turkey's state centres for gifted and talented children)? The question "what does an IQ score mean?" is usually asked at exactly this moment of confusion. Read correctly, intelligence test results provide very valuable information about how a child learns; read incorrectly, they can trap a child inside a label that follows them for years. In this article I explain how IQ scores are calculated, what the average means, why index scores can matter more than the total score, and what an intelligence test does not measure.
What Does an IQ Score Mean? The Basic Logic
IQ is the abbreviation of "intelligence quotient", which is translated into Turkish as "zekâ bölümü". The word "quotient" comes from history: in the first intelligence tests, a child's mental age was divided by their chronological age and multiplied by a hundred. The tests used today no longer make this calculation. Modern intelligence tests compare a person's performance with the performance of a large comparison group of people of the same age.
In this comparison, scores are scaled so that the mean is 100 and the standard deviation is 15. In practical terms, this means:
- 100 is exactly in the middle. Roughly half of people of the same age score below 100 and half above.
- The range from 85 to 115 is where the great majority of peers fall. Roughly two out of every three people are in this range.
- The range from 70 to 130 covers almost everyone. Scores outside this range are relatively rare.
So a score of 108 is a result within the "average" range, slightly above the mean. A score of 92 is in the same average range. The difference between these two scores is often too small to be noticed in daily life.
Next to the scores, reports sometimes also give a percentile rank. For example, a score of 115 corresponds to roughly the 84th percentile; that is, the person scored higher than about 84 per cent of their peers. A percentile rank shows not what percentage of questions you got right but where you stand within the comparison group.
Some of the people who search online for "what does an IQ score mean" are adults who have taken a test that popped up on social media and got a result such as 140 or 95. The results of tests like these should be approached with caution. Clinical intelligence tests are administered one to one by a trained practitioner, the timing and instructions are standardised, and scores are calculated against a large comparison group drawn from that country's population. With online tests, it is often unclear whom you are being compared with, and the results may be tuned to please the user. Curiosity is natural, but it is healthier not to define yourself by a number like that.
How Are Intelligence Test Score Ranges Labelled?
In reports, score ranges are usually expressed with descriptive words. Although these labels differ slightly from test to test, the general framework is as follows:
- 130 and above: Very superior
- 120–129: Superior
- 110–119: High average
- 90–109: Average
- 80–89: Low average
- 70–79: Borderline
- 69 and below: Extremely low
These words need to be read with a caveat: they describe not a person's worth but where their performance on a test stands relative to their peers. A "low average" child is a child who keeps learning, is developing and has strengths. A "superior" child is not someone who has to succeed at everything.
Confidence Intervals: Why You Can't Rely on a Single Number
No measurement is perfect. If a child took the same test on two different days, they might score a few points differently because of factors such as tiredness, attention, anxiety or luck. That is why a good report gives a confidence interval alongside the total score.
For example, the statement "Full scale score 108, 95 per cent confidence interval 102–114" means that the child's true score is highly likely to lie within this range. This information is particularly important near threshold values. If the confidence interval of a child who scored 128 also includes 130, saying "they fell below 130" may be misleading. Likewise, if the interval of a child who scored 72 also extends below 70, the result must be interpreted carefully and together with other information.
Beyond measurement error, the conditions on the day of the test can also affect the result. A child who did not sleep well the night before, left home after an argument that morning, or was uneasy about being alone in an unfamiliar room with an unfamiliar adult may not be able to show their true capacity. In children who speak a language other than Turkish at home, or who came to Turkey later in childhood, low scores, particularly on the verbal subtests, may reflect language experience more than intelligence. That is why a good report also notes the child's behaviour and cooperation during the test; the result becomes meaningful together with these observations.
An intelligence score is not a point but a range, and that range shows only one side of a child.
Index Scores: More Than the Total
The version of the WISC widely used in Turkey, one of the intelligence tests most often used with children, gives four separate index scores alongside the total score:
- Verbal Comprehension: Vocabulary, making connections between concepts, verbal reasoning and general knowledge.
- Perceptual Reasoning: Solving visual patterns, making connections between shapes and parts, and finding non-verbal solutions to new problems.
- Working Memory: Holding information in mind for a short time and working with it; for example, doing a sum in your head or keeping an instruction in mind while carrying it out.
- Processing Speed: Scanning and processing simple visual information quickly and accurately.
For detailed information on how this test is administered and when it is requested, you can take a look at the article on the WISC intelligence test.
The total score is a summary of these four areas. But when there are large differences between the indices, the total score falls short of describing the child. To return to the example at the beginning of this article: a child with a Verbal Comprehension score of 121, Working Memory of 86 and Processing Speed of 82 may have a total score of 108; but this child does not learn like an "average" pupil. They are very strong verbally, ask deep questions in class and have a rich vocabulary. On the other hand, they can't finish written exams in time, struggle to keep long instructions in mind, and find copying and writing tasks tiring. The teacher wonders, "Why does such a clever child get such low marks in exams?" and the family gets cross: "He doesn't work, he's being lazy."
This picture may be related to conditions such as attention difficulties, specific learning difficulties or anxiety, and needs to be assessed separately. For information on how specific learning difficulties are identified, you can read the article on specific learning difficulty. But at least this much is clear: this child's need is not to study more, but for the way they learn to be understood.
What Does an IQ Score Mean, and What Doesn't It Mean?
Intelligence tests measure some of the cognitive skills that matter at school and in life, such as reasoning, problem solving, verbal understanding, working memory and processing speed. But there are many things an intelligence test does not measure:
- Creativity and imagination: Generating original ideas and thinking outside the usual.
- Emotional and social skills: Understanding other people's feelings, making friends, resolving conflicts.
- Motivation and perseverance: Being able to keep going when things are hard and seeing a task through to the end.
- Practical skills: Solving the problems of daily life, manual dexterity, artistic and sporting talents.
- Character: Honesty, compassion, a sense of responsibility.
School success does not depend on intelligence alone either. A child with an average intelligence score who studies regularly and loves learning can be far more successful than a child with a high intelligence score who is anxious or poorly motivated.
Another important point: intelligence scores are not fixed, especially at a young age. In childhood, education, a stimulating environment, health and emotional circumstances can affect scores. Scores become more stable with age, but it is still not right to treat a single test result as a verdict valid for a lifetime.
Thresholds: Giftedness and Intellectual Disability
One of the things families most want to know is how intelligence scores relate to particular thresholds.
Giftedness: Scores of 130 and above are often associated with giftedness. However, identifying giftedness does not depend on a single number. In Turkey, selection of pupils for BİLSEM follows its own process made up of stages such as nomination based on the class teacher's observations, a group screening and an individual assessment; the details of this process may change over the years. For information on how gifted children can be recognised in daily life, you can take a look at the article on signs of a gifted child.
Intellectual disability: Scores of approximately 70 and below may call for assessment for intellectual disability. However, this diagnosis is not made on the basis of the intelligence score alone; the person must also have marked difficulties compared with their peers in areas such as daily living skills, communication, self-care and social adjustment. The diagnosis and any necessary reports are determined through a comprehensive assessment in hospitals that also involves doctors.
In both cases, a decision is not made on the basis of a single test result. Especially for results close to threshold values, the confidence interval and other information must always be taken into account.
How Should You Explain the Result to Your Child and Others?
An intelligence test result can easily become a topic of conversation within the family, even the extended family. A relative asking during a festive holiday visit, "What did they get on the test?", a parent comparing two siblings by their scores, a child labelled at school as "the one with the high IQ"... Situations like these can do a child more harm than good.
A few suggestions:
- Don't share the score with your child. A number can shape a child's view of themselves more than it should. A high score can turn into the pressure "I must always succeed", and a low score into the belief "I'm stupid."
- Describe their strengths concretely. Sentences such as "You think really well with words" or "You're very patient at solving puzzles" are far more meaningful than a number.
- Frame the areas they find difficult as a need, not a deficiency. "Your brain likes thinking deeply rather than writing fast; you may need a bit more time in exams."
- Don't compare siblings or relatives. Every child's cognitive profile is different.
- Share the result with the school with a focus on recommendations. When sharing it with the teacher, focus less on the scores and more on how the child can be supported in class.
When Should You Seek Support?
An intelligence test is usually not the solution to a problem but the beginning. It can be helpful to see a specialist in the following situations:
- If there is a big gap between the test results and the child's performance at school
- If there are marked differences between the indices and what this means has not been explained to you
- If the child is constantly experiencing failure at school, feels inadequate or doesn't want to go to school
- If the result has led to tension, comparison or intense anxiety within the family
In work with children and adolescents, the psychologist considers test results together with the child's emotional world and daily life. In child and play therapy, feelings that remain in the shadow of an intelligence score, such as a sense of failure, anxiety or perfectionism, can be addressed.
Frequently Asked Questions
Does an IQ score change over time?
It can change, especially at a young age. Education, environmental stimulation, health and emotional circumstances can affect scores. In adolescence and adulthood scores become more stable, but a single measurement should never be seen as a definite and unchangeable verdict.
Their intelligence score is high but their school results are poor. How can that be?
School success does not depend on intelligence alone. Attention difficulties, specific learning difficulties, anxiety, low motivation or large differences between the indices can lead to this. Rather than the label "lazy", it is far more useful to try to understand the reason for the gap.
How often can an intelligence test be repeated?
Repeating the same test at short intervals leads the child to remember the questions and the score to rise artificially. For this reason, reassessment is usually done after a long gap, such as at least one or two years, and for a concrete reason. It is healthiest to decide on the right timing together with the specialist who carried out the first assessment.
Can adults have an intelligence test too?
Yes. There are intelligence tests developed for adults, and they may be used particularly in assessing adult attention deficit, when a learning difficulty is suspected, or in some neurological conditions. The reason for the assessment determines which test is chosen.
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Eda Erkan Alapala
Klinik Psikolog. İstanbul Kent Üniversitesi Klinik Psikoloji Tezli Yüksek Lisans mezunu; bilişsel davranışçı terapi, çocuk merkezli oyun terapisi ve çocuk-ergen psikoterapisi alanlarında eğitimlerini tamamlamıştır.
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