Blog and Guides
Original, sourced articles and reference pages that explain what each CoreSkillAI test measures and how to read your results.
Articles
What Is a Good IQ Score? Ranges, Percentiles and What They Mean
What counts as a good IQ score, how IQ ranges map to percentiles, and why a single number says less than most people think.
Are Online IQ Tests Accurate? What Reliability and Norming Actually Mean
Why most online IQ tests cannot give a trustworthy score, what a proper test needs, and how to judge any test you find online.
Fluid vs Crystallized Intelligence: The Difference and Why It Matters
Fluid reasoning and crystallized knowledge are two different parts of intelligence. How Cattell and Horn described them and how each changes with age.
The Flynn Effect Explained: Why IQ Scores Rose for a Century
Raw IQ scores rose about three points per decade through most of the 20th century. What caused it, and why the trend has reversed in some countries.
How to Improve Working Memory: What the Evidence Supports
Practical, evidence-based ways to get more out of working memory: chunking, sleep, exercise and strategy, and what does not work.
Does Brain Training Work? A Look at the Research
Brain-training games improve the games. Whether that carries over to everyday thinking is a different question, and the research is not encouraging.
How to Improve Your Reaction Time (and How to Measure It Fairly)
What limits human reaction time, what practice can and cannot change, and why your screen and mouse matter more than you expect.
The Big Five Personality Traits Explained
Openness, conscientiousness, extraversion, agreeableness and neuroticism: what each trait measures, how stable they are, and how they differ from MBTI.
EQ vs IQ: What Each Predicts and What the Popular Claims Get Wrong
Emotional intelligence and IQ measure different things. What the research says about each, and why the "EQ matters more" slogan is overstated.
Colour Blindness: Types, Causes and How Testing Works
Protan, deutan and tritan deficiencies explained, how common each is, why it affects men more often, and what online screening can and cannot tell you.
How to Type Faster: Accuracy First, Then Speed
A practical method for raising typing speed: technique, deliberate practice and error handling, based on what large typing studies show.
The Stroop Effect Explained: Why Reading Gets in the Way of Seeing
The Stroop effect shows how automatic reading interferes with naming colours. What it reveals about attention and cognitive control.
Sleep and Cognitive Performance: What Short Nights Do to Your Brain
How sleep loss slows reaction time, narrows attention and distorts self-assessment, and what that means before you take any cognitive test.
Mental Rotation: How We Turn Objects in the Mind
Shepard and Metzler showed that people rotate mental images at a measurable speed. What mental rotation measures and how spatial skill can be trained.
Reference pages
IQ Score Chart: Ranges, Percentiles and Classifications
A full IQ score chart from 55 to 160 with percentiles, plus a converter between IQ and percentile.
Average Reaction Time by Age: What the Research Shows
How simple and choice reaction time change from the twenties to old age, with figures from published studies and what affects your own result.
Average Typing Speed: WPM Benchmarks and a Calculator
What counts as slow, average and fast typing, with figures from a 168,000-person study and a words-per-minute calculator.
IQ Tests for Kids: What Parents Should Know
How children are properly assessed, why an online adult-style test is not suitable for a child, and what to do if you have concerns.
Digit Span Norms: What Is a Normal Memory Span?
Typical forward and backward digit span for adults, how the task works, and what a short or long span does and does not mean.
Big Five Scores: How to Read Low, Average and High
How to interpret low, average and high scores on each Big Five trait, and why no score on any trait is "bad".
Emotional Intelligence Scores: What Your EQ Result Means
What a self-report EQ score measures, how it differs from ability-based tests, and how to use your result sensibly.
Methodology
How each test is built, scored and corrected.
The tests
Every article links to the test it explains. All ten tests are free and need no account: see all tests.