CHC Theory

We all come to this world with a certain physical and mental capacity / potential power. Our innate physical dispositions draw a general picture on topics such as how healthy a life we will lead, which diseases we are susceptible to, or which kind of sports we will be better at. Similarly, many mental abilities such as attention, memory, reasoning or planning have an innate potential. However, to what extent our physical and mental potential will be actualized is determined by personal, parental and social investment put into the related abilities. While abilities invested on thrive over time, those who have not had the opportunity to state themselves will stop its development and lie fallow. Especially the first years of childhood is of utmost importance in actualizing these potentials. Over the years, skills nourished with exercises will grow stronger and improve. Between the ages of thirty and forty, the development of skills will cease and losses will begin. With advancing age, the amount of loss will increase. At this stage, exercises become important protective factors in decreasing loss and enabling a healthy aging.

Just as physical exercises need to train all muscle systems in a balanced manner, mental exercises need to train different skills groups in a proportional manner. The current levels of skills need to be determined accurately and activated with exercises suitable to these levels. In general terms, traditional mental exercise programs focus on inclusive or general mental processes such as attention, memory, verbal and quantitative procedures. However, there are other unique skills that can be empirically separated. The CHC theory, which is a modern approach, provides a good theoretical framework to classify these skills and model the relationships between them. On the one hand the mental exercise applications developed within Brainquire are defined within the context of basic processes such as attention and memory on the one side, on the other hand the unique skills or skill groups they activate are classified under the CHC theory. This dual classification provides the opportunity for a scientifically far more powerful exercise program.

CHC Theory

Integrating Cattell-Horn’s Fluid Intelligence-Crystallized (Gf-Gc) Intelligence Theory with Carroll’s Three-Stratum Model, McGrew established the Cattel-Horn-Carrol Cognitive Skills Model. The CHC Model has been revised and expanded by Flanagan. The hierarchic structuring suggested in the CHC Model is quite similar to Carroll’s Three-Stratum Model. On top of the hierarchy is the general intelligence factor shown with the lower-case letter “g”. On the bottom stratum is the more than 70 limited cognitive skills defined as empirical. In the middle stratum is the limited number of broad skill areas with Cattell- Horn’s Gf-Gc skills taking the lead shown with the capital letter “G”. The broad skill areas defined so far under CHC is provided below.


1. Gc – Crystallized Intelligence
2. Gf – Fluid Intelligence
3. Gq – Quantitative Reasoning
4. Grw – Reading & Writing Ability
5. Gsm – Short-Term Memory
6. Glr – Long-Term Storage and Retrieval
7. Gv – Visual Processing
8. Ga – Auditory Processing
9. Gs Processing Speed
10. Gt – Decision/Reaction Time/Speed
11. Gkn – General Knowledge
12. Gh – Tactile abilities
13. Gk – Kinesthetic Abilities
14. Go – Olfactory Abilities
15. Gps – Psychomotor Speed

The first ten of these skills are those that have been mostly studied. Classifications related to broad skill areas continue to concentrate under the light of new studies.

Fluid Intelligence (GF)

Fluid Intelligence refers to the deductive and inductive reasoning conducted during deducing against a new material or process. Some of the related skills are:

Deductive Reasoning (RG)
Quantitative Reasoning (RQ)
Induction (I)

Crystallized Intelligence (GC)

Primarily it is a verbal or language based mine of information. It generally represents the skills developed through the investment of other skills during educational experiences and general life experiences.

Language Development (LD)
Lexical Knowledge (VL)
Listening Ability (LS)
General Verbal Information (K0)
Information About Culture (K2)

Quantitative Reasoning (GQ)

Quantitative Reasoning contains Mathematical Knowledge and Mathematic Achievement. It represents the skill of using and processing quantitative information and numerical symbols.

Mathematical Knowledge (KM)
Mathematical Achievement (A3)

Short-Term Memory (GSM)

Short-Term Memory is the ability to catch and store information on an instant awareness level and then being able to use it in a short period of time.

Memory Span (MS)
Working Memory (WM)

Long-Term Storage and Retrieval (GLR)

Long Term Storage and Retrieval refers to the ability to store the information in the long-term memory or the ability to fluently retrieve the new or previously acquired information (concept, idea, topic, name) from the long-term memory.

Associative Memory (MA)
Meaningful Memory (MM)
Free Recall Memory (M6)
Ideational Fluency (FI)
Associational Fluency (FA)
Expressional Fluency (FE)

Visual Processing (GV)

Visual Processing is the skill of producing, perceiving, analyzing, synthesizing, storing, recalling, changing and transforming visual patterns or stimuli and being able to think with them.

Visual Memory (MV)
Spatial Relations (SR)
Closure Speed (CS)
Visualization (Vz)

Auditory Processing (Ga)

Auditory Processing is the skill of perceiving, analyzing and synthesizing the sounds between audial stimuli, differentiating fine differences between audio sounds (complex musical structures etc.) and differentiating speech in cases where there are mixing stimuli.

Phonetic Coding – Analysis (PC: A)
Phonetic Coding – Synthesis (PC: S)
Speech Sound Discrimination (US)

Processing Speed (Gs)

Processing Speed is the skill of fluently and automatically conducting a cognitive duty when under pressure in order to protect focused attention and concentration.

Perceptual Speed (P)
Rate of Test Taking (R9)

Decision/Reaction Time/Speed (Gt)

Decision/Reaction Time/Speed is the speed in accurate reaction or decision making.

Simple Reaction Time (R1)
Mental Comparison Speed (R7)

Reading and Writing (GRW)

It has been classified as a part of Crystallized Intelligence (Gc) by Cattle and Horn. By Carrol, it has been accepted as a field of performance rather than a skill. It is classified as an independent skill in the CHC theory.

Reading Decoding (RD)
Reading Comprehension (RC)
Reading Speed (RS)