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Build your logical reasoning skills
Explore reasoning methods, common mistakes, and ways to practise.
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The reading room
Follow a question. Find a new idea.
Explore reasoning methods, patterns, and the brain. Start with a practical guide, try its method in a free set, or browse the tidbits for a short discovery.
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How to practise pattern recognition
Spot repeating shapes and changing rules with four worked exercises.
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The basics
What is IQ?
Understand what an IQ score describes, and what it leaves out.
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Go deeper
Understanding IQ scores
A guide to scores, percentiles, and the limits of interpretation.
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Stay curious
Meet your remarkable brain
Explore the structures and functions behind everyday thinking.
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Perspectives
IQ, EQ, and artificial intelligence
Explore the relationship between cognitive and emotional skills.
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Curious minds / 40 brain tidbits
A little knowledge. A new question.
Explore the brain, learning and what IQ can tell us. Choose a topic or follow your curiosity. Open any tidbit for a short explanation and its source.
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40 of 40 tidbits· Open a card to go a little deeper
Brain Structure & FunctionSmall but mightyAn adult human brain weighs roughly three pounds.
A little perspective
Its regions work together on movement, sensation and thought.
Source: NIH: Information about the brainBrain Structure & FunctionNeural universeA study estimated an average of about 86 billion neurons in adult male brains.
A little perspective
This is a sample estimate, not an exact count for everyone.
Source: Azevedo et al. (2009)Brain Structure & FunctionMessages on the moveNeurons communicate using electrical signals and chemical messengers.
A little perspective
Signals travel through a process, not an instantaneous jump.
Source: NIH: Information about the brainBrain Structure & FunctionThe brain's supply networkBlood brings oxygen and nutrients to brain cells.
A little perspective
The brain depends on its circulation, just as other organs do.
Source: NIH: Information about the brainBrain Structure & FunctionThe cerebellum's hidden scaleThe cerebellum contains most brain neurons despite its relatively small size.
A little perspective
Neuron count and brain volume tell different stories.
Source: Azevedo et al. (2009)Energy & PerformanceAn energy-hungry organThe brain accounts for roughly one-fifth of the body's energy use.
A little perspective
Much of this supports its ongoing activity.
Source: NIH: Information about the brainEnergy & PerformanceWater in the brainA widely cited estimate puts brain tissue at about 73% water by weight.
A little perspective
That is not a formula for how much water to drink.
Source: USGS: Water and the human bodyEnergy & PerformanceMental calories, in contextThe brain uses energy even when you are not solving puzzles.
A little perspective
A daily estimate does not measure the calories used by a particular thought.
Source: NIH: Information about the brainEnergy & PerformanceOxygen lifelineBrain cells depend on a continuing oxygen supply.
A little perspective
A universal countdown cannot describe every situation involving oxygen loss.
Source: NIH: Information about the brainEnergy & PerformanceMovement and thinkingResearch in older adults links physical activity with aspects of cognitive health.
A little perspective
That does not promise an immediate score increase after a short walk.
Source: NIA: Cognitive healthMemory & SleepNighttime learning labSleep supports the formation and maintenance of memories.
A little perspective
Being asleep does not mean the brain has switched off.
Source: NHLBI: Why sleep is importantMemory & SleepNaps have limitsNaps may boost alertness, but can also make it harder to fall asleep at night.
A little perspective
Timing matters as well as whether you take a nap.
Source: NHLBI: Healthy sleep habitsMemory & SleepSleep loss and attentionInsufficient sleep can affect thinking, concentration and reactions.
A little perspective
One tired performance is not a complete picture of your ability.
Source: NHLBI: Sleep deprivationMemory & SleepWhy do we dream?Scientists still debate what functions dreams serve.
A little perspective
A memorable dream invites curiosity, but does not prove a single theory.
Source: Boston University: Understanding sleepMemory & SleepTired judgmentSleep deficiency can interfere with everyday functioning and safety.
A little perspective
Recognising impairment is more useful than assigning every sleepless night an alcohol equivalent.
Source: NHLBI: Sleep deprivationLearning & PlasticityA changing brainExperience can change connections between neurons: part of neural plasticity.
Learning & PlasticityPractice and connectionsRepeated activity can influence the strength of neural connections.
A little perspective
After practice, ask: what would I try differently next time?
Source: NIH: Information about the brainLearning & PlasticityMusic is worth learning for itselfA 2020 meta-analysis found no reliable general cognitive benefit from music training after accounting for study quality.
A little perspective
Enjoying music does not require a promise of higher IQ.
Source: Sala & Gobet (2020)Learning & PlasticityBilingualism: an open questionStudies link bilingualism with later dementia symptoms more consistently than with lower disease incidence.
A little perspective
Learning a language is not a proven way to prevent dementia.
Source: Anderson et al. (2020)Learning & PlasticityMental rehearsal has limitsIn one motor-learning experiment, mental practice alone did not improve learning in novices without task experience.
A little perspective
Imagining an action and practising it are not interchangeable.
Source: Mental practice experiment (2014)Intelligence QuotientWhy the average is 100IQ scales commonly set the reference group's average to 100.
A little perspective
It is a comparison with test norms, not a percentage correct.
Source: Pearson: Assessment primer (PDF)Intelligence QuotientReading the bell curveCommon IQ scales place more scores near the average and fewer at the extremes.
A little perspective
Different scales can assign different numbers to the same percentile.
Source: Pearson: Assessment primer (PDF)Intelligence QuotientGiftedness beyond a cutoffGiftedness can involve exceptional performance or potential in one or more domains.
A little perspective
Support should consider the learner's context, not just one number.
Source: NAGC: What is giftedness?Intelligence QuotientA score is not a diagnosisIntellectual disability involves limitations in intellectual functioning and adaptive behaviour, with developmental onset.
A little perspective
An online IQ score cannot establish that diagnosis.
Source: AAIDD: Defining criteriaIntelligence QuotientMensa membershipMensa's qualifying threshold is at or above the 98th percentile on an accepted intelligence test.
Intelligence QuotientReasoning and knowledgeIntelligence includes reasoning, learning and understanding complex ideas.
A little perspective
Different tasks sample different abilities; one puzzle cannot capture them all.
Source: MedlinePlus: Intelligence and geneticsIntelligence QuotientStability does not mean fixedA Scottish study found substantial links between intelligence scores at ages 11 and 90.
A little perspective
Group-level stability does not mean every individual's score stays unchanged.
Source: Deary et al. (2013)Intelligence QuotientIQ and health: a relationshipA Scottish study associated higher childhood intelligence with lower mortality from several causes.
A little perspective
An association does not establish one cause or predict an individual's future.
Source: Calvin et al. (2017)Intelligence QuotientEducation can make a differenceA meta-analysis of quasi-experimental studies found that additional education improved intelligence-test performance.
A little perspective
Estimates describe study groups, not guaranteed gains for every learner.
Source: Ritchie & Tucker-Drob (2018)Intelligence QuotientNutrition is part of the pictureNutrition is one of several environmental influences on intelligence development.
A little perspective
No single ingredient determines a person's ability.
Source: MedlinePlus: Intelligence and geneticsIntelligence QuotientIQ and creativityResearch distinguishes creative potential from creative achievement when studying their relationship with intelligence.
Intelligence QuotientAbilities at workResearch on work performance considers both general and specific cognitive abilities.
A little perspective
Which abilities matter depends partly on what a job requires.
Source: Research on workplace abilitiesIntelligence QuotientContext matters in assessmentIdentifying gifted learners calls for multiple sources of evidence and attention to diverse backgrounds.
A little perspective
A single assessment cannot provide every useful perspective.
Source: NAGC: IdentificationIntelligence QuotientSkills change differently with ageSome thinking processes become slower with age while vocabulary and knowledge can remain strengths.
A little perspective
Aging does not affect every skill in the same way.
Source: NIA: Aging and thinkingIntelligence QuotientMany genes, many influencesIntelligence is influenced by many genetic and environmental factors.
A little perspective
There is no single gene that determines an IQ score.
Source: MedlinePlus: Intelligence and geneticsIntelligence QuotientBrain training has limitsReviews of chess, music and working-memory training found limited evidence of broad transfer to other abilities.
A little perspective
Improving at a practised task differs from improving at every kind of thinking.
Source: Sala & Gobet (2017)Intelligence QuotientEarly scores are not destinyEarlier intelligence scores can predict later educational outcomes in groups.
A little perspective
Prediction still leaves room for education, opportunity and individual change.
Source: Ritchie & Tucker-Drob (2018)Intelligence QuotientHigh ability, individual needsGifted learners can need social and emotional support as well as academic support.
A little perspective
Strength in one area does not erase needs in another.
Source: NAGC: Social and emotional developmentIntelligence QuotientExtreme scores need contextIQ numbers are meaningful only with the scale and test that produced them.
A little perspective
A large number alone does not establish precise rarity or exceptional talent.
Source: Mensa: IQ test FAQsIntelligence QuotientNot the whole storyIntelligence is complex, and researchers use different definitions and measures.
A little perspective
Treat a test result as one piece of information, not a description of your worth.
Source: MedlinePlus: Intelligence and geneticsPut your knowledge into practice
Choose from six free sets: start with deductions, ordering, and conditions, then work through linked clues and counterexamples.
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