About ACIS

The Science of
Measuring Intelligence.

ACIS represents the culmination of decades of research in differential psychology, psychometrics, and cognitive assessment—distilled into a free, accessible instrument that rivals clinical-grade tests.

Our Mission: Democratizing Cognitive Assessment

Traditional clinical IQ tests—such as the Wechsler Adult Intelligence Scale (WAIS), Stanford-Binet, and Woodcock-Johnson—cost $200-$500 or more and require professional administration by licensed psychologists. This places accurate cognitive assessment out of reach for the vast majority of people worldwide.

ACIS was created to change this paradigm. We believe that everyone deserves access to high-quality cognitive assessment, regardless of their financial resources or geographic location. By leveraging modern web technologies and rigorous psychometric methodology, we've built an instrument that provides clinical-grade measurement at zero cost.

This isn't about replacing professional evaluation—it's about expanding access. ACIS empowers individuals to understand their cognitive profile: their strengths, their areas for growth, and their unique pattern of abilities across multiple domains. This self-knowledge has profound implications for educational planning, career development, and personal growth.

Psychometric Excellence

ACIS isn't just another online quiz—it's a psychometrically rigorous instrument built to the highest standards in the field. Our development process followed the same methodology used by major test publishers.

.99
g-Loading
>.95
Reliability
.87
WAIS-IV Validity
2,800+
Norming Sample

Understanding These Metrics

  • g-Loading (.99): This extraordinary correlation with the general factor of intelligence (g) means ACIS captures the essence of what intelligence tests measure—the common cognitive ability that predicts performance across virtually all mental tasks. Most professional tests achieve g-loadings between .85-.95. For more on the general factor, see Deary et al.'s research on intelligence and educational achievement.
  • Reliability (>.95): Internal consistency reliability measures how well test items hang together. A reliability of .95+ indicates that ACIS scores are highly consistent and measurement error is minimal. This exceeds the typical threshold of .90 for clinical use established by the Standards for Educational and Psychological Testing.
  • Convergent Validity (.87): This correlation with the WAIS-IV—the most widely used clinical IQ test—demonstrates that ACIS measures the same constructs. An r of .87 is remarkably high for an online versus proctored comparison. See Schmidt & Hunter (1998) on the importance of validity in assessment.
  • Normative Sample (2,800+): All scores are compared against a robust sample, enabling accurate percentile rankings and standardized scores. Our norms are continuously refined as data accumulates, following best practices outlined by the American Educational Research Association.

Built on CHC Theory: The Gold Standard

ACIS is grounded in the Cattell-Horn-Carroll (CHC) theory—the most comprehensive and empirically validated framework for understanding human cognitive abilities. Developed through the integration of Raymond Cattell and John Horn's Gf-Gc theory with John Carroll's three-stratum model (based on factor analysis of 460+ datasets), CHC theory represents the consensus view in differential psychology.

Every major intelligence test developed since 2000—including the WAIS-IV/V, WISC-V, Stanford-Binet 5, Woodcock-Johnson IV, and KABC-II—is explicitly built on CHC theory. ACIS follows this tradition, ensuring our results are interpretable within the same framework used by clinicians and researchers worldwide. For comprehensive coverage of CHC theory and its applications, see Flanagan & Harrison's Contemporary Intellectual Assessment (2012).

The Six Cognitive Domains We Measure

VCI Verbal Comprehension

Crystallized intelligence—vocabulary, general knowledge, verbal reasoning, and language mastery.

FRI Fluid Reasoning

Novel problem-solving using logic, pattern recognition, and abstract thinking without prior knowledge.

VSI Visual-Spatial

Mental manipulation of visual information, spatial reasoning, and pattern analysis.

WMI Working Memory

Holding and manipulating information in conscious awareness—the mental workspace.

PSI Processing Speed

Speed and efficiency of simple cognitive operations under time pressure.

QRI Quantitative Reasoning

Mathematical reasoning, numerical problem-solving, and quantitative concept application.

With 20 specialized subtests distributed across these domains, ACIS provides not just a single IQ score, but a comprehensive cognitive profile. This multi-dimensional approach reveals patterns that a single score cannot—perhaps strong verbal abilities paired with relatively weaker processing speed, or exceptional fluid reasoning alongside typical working memory.

Development Methodology

ACIS was developed following established psychometric principles and industry best practices. The process mirrors that used by major test publishers like Pearson and Riverside.

1. Theoretical Foundation & Blueprint

We began by establishing CHC theory as our structural foundation. A detailed test blueprint specified which broad and narrow abilities each subtest would target, ensuring comprehensive coverage of the six primary cognitive domains without construct underrepresentation.

2. Item Development & Expert Review

Hundreds of items were developed for each subtest, drawing on established task paradigms from the psychometric literature. Items were reviewed for clarity, cultural sensitivity, and alignment with target constructs. Problematic items were revised or eliminated.

3. Pilot Testing & Item Analysis

Initial item pools were administered to pilot samples. Classical Test Theory (CTT) statistics—item difficulty, discrimination indices, point-biserial correlations—were computed to identify optimal items. Items with poor psychometric properties or unintended construct contamination were removed.

4. Norming Study (N = 2,800+)

The refined instrument was administered to a large normative sample. Raw scores were converted to standardized scores (M=100, SD=15 for composites; M=10, SD=3 for subtests) using established statistical procedures. Normative tables enable comparison of individual performance to the reference population.

5. Reliability & Validity Analysis

Internal consistency reliability was computed using Cronbach's alpha and split-half methods. Construct validity was examined through factor analysis (confirming the intended structure) and convergent validity studies (correlation with established measures like the WAIS-IV).

6. Continuous Refinement

ACIS functions as a living instrument. As additional data accumulates, norms are refined, items are analyzed for drift or bias, and the overall psychometric quality is continuously monitored and improved.

How ACIS Compares to Professional Tests

Feature ACIS Full Scale WAIS-IV Stanford-Binet 5
Number of Subtests 20 10 core + 5 supplemental 10
Cognitive Domains 6 4 5
Theoretical Framework CHC CHC CHC
IQ Range 40-160 40-160 40-160
Administration Self-administered online Professional required Professional required
Cost $0 (Free) $200-$500+ $200-$400+
Accessibility Worldwide, instant Appointment required Appointment required

Important distinction: While ACIS achieves comparable psychometric quality, it differs from WAIS-IV and Stanford-Binet in administration format. Professional tests include in-person observation of behavior, rapport building, and qualitative assessment that self-administration cannot replicate. For official purposes (disability accommodations, Mensa membership, forensic evaluation), proctored professional testing remains the standard. ACIS excels for personal insight, educational planning, and research applications.

Frequently Asked Questions

What is my IQ and how can ACIS help me find it?

Your IQ (Intelligence Quotient) is a standardized measure of cognitive ability compared to the general population. A score of 100 represents the average, with each 15-point deviation representing one standard deviation. ACIS provides a comprehensive assessment across 20 subtests covering six cognitive domains, yielding a Full Scale IQ (FSIQ) that reflects your overall cognitive ability, plus domain-specific index scores that reveal your unique profile of strengths and weaknesses. Simply take the assessment to discover your score.

How can I measure my intelligence accurately online?

Accurate intelligence measurement requires: (1) a comprehensive test that assesses multiple cognitive domains—not just one type of reasoning; (2) proper standardization with normative data from a large reference sample; (3) demonstrated reliability and validity. Most online IQ tests fail on all three counts. ACIS uses 20 subtests measuring six CHC domains, is normed on 2,800+ participants, and demonstrates .99 g-loading with >.95 reliability. This combination makes it the most valid free online assessment available.

Is there really a free scientific IQ test that works?

Yes—but ACIS is rare. The vast majority of "free IQ tests" online are entertainment products with no psychometric rigor. They often give inflated scores to encourage sharing. ACIS is fundamentally different: built on CHC theory, developed using established psychometric methodology, validated against the WAIS-IV (r=.87), and providing the same measurement precision as tests costing hundreds of dollars. The difference is accessibility, not quality.

Meet the Creator

JV

Javier Vargas

Creator & Principal Developer

Javier Vargas developed ACIS with a singular mission: making clinical-grade cognitive assessment accessible to everyone, regardless of financial resources or geographic location. His work bridges differential psychology, psychometrics, and modern web technology.

Drawing on the CHC framework and established psychometric methodology, he designed ACIS to meet the rigorous standards of traditional clinical instruments while leveraging the accessibility and reach of the internet. The result is an instrument that democratizes access to cognitive self-understanding.

Javier maintains an active presence in the cognitive testing community, gathering feedback to continuously improve ACIS and ensure it serves users' needs effectively.

Contact on Reddit

Scientific References

ACIS draws on the foundational research in intelligence and psychometrics. For those wishing to explore the scientific literature:

  • Carroll, J.B. (1993). Human Cognitive Abilities: A Survey of Factor-Analytic Studies. Cambridge University Press. — The foundational work establishing the three-stratum model of cognitive abilities.
  • McGrew, K.S. (2009). CHC theory and the human cognitive abilities project. Intelligence, 37(1), 1-10. DOI: 10.1016/j.intell.2008.08.004 — Key paper on the integration and evolution of CHC theory.
  • Schneider, W.J. & McGrew, K.S. (2018). The Cattell-Horn-Carroll theory of cognitive abilities. In D.P. Flanagan & E.M. McDonough (Eds.), Contemporary intellectual assessment (4th ed.). Guilford Press.
  • Horn, J.L. & Cattell, R.B. (1966). Refinement and test of the theory of fluid and crystallized general intelligences. Journal of Educational Psychology, 57(5), 253-270. DOI: 10.1037/h0023816
  • Jensen, A.R. (1998). The g Factor: The Science of Mental Ability. Praeger. — Comprehensive treatment of general intelligence and its measurement.
  • Wechsler, D. (2008). WAIS-IV Administration and Scoring Manual. Pearson. — Technical documentation for the most widely used adult IQ test.