How scientists organise thinking skills: CHC, the NIH Toolbox and executive functions

Brain training games use labels such as memory, attention and reasoning. Scientists organise these ideas in several ways. The Cattell-Horn-Carroll model groups cognitive abilities. The NIH Toolbox provides research measures. Executive-function models describe processes involved in controlling thoughts and actions. They answer related questions, but their categories are not interchangeable.

freegama keeps four daily skills: Memory, Focus & speed, Logic & reasoning, and Numbers & words. These organise the games you choose. Understanding the research vocabulary helps explain a task without turning its score into a diagnosis.

CHC: a structure for cognitive abilities

Cattell-Horn-Carroll, usually shortened to CHC, combines work by Raymond Cattell, John Horn and John Carroll. Carroll's 1993 book, Human Cognitive Abilities, set out a three-stratum account: narrow abilities, broad abilities and a general factor. Kevin McGrew's 2009 editorial explained the synthesis and the shared terminology that grew from it.

Fluid reasoning means working through unfamiliar problems. Processing speed concerns performing relatively simple cognitive tasks quickly. CHC also distinguishes acquired knowledge, visual processing and memory-related abilities. These are broader ideas than individual game rules.

The names have developed over time. In McGrew's account of the WJ IV, an assessment publisher's overview, short-term working memory, or Gwm, clarifies the older short-term-memory label, Gsm. Its components include memory span, working-memory capacity and attentional control. This describes how an assessment framework handles information held briefly and used during a task.

When reading a category, ask which version and definition the author uses. A familiar word does not guarantee identical tasks or scoring.

The NIH Toolbox: a battery of measures

A battery is a set of measures used together. Sandra Weintraub and colleagues' 2013 paper described the NIH Toolbox Cognition Battery. It covered executive function, attention, episodic memory, working memory, language and processing speed through seven measures.

Episodic memory means remembering particular events or experiences. The battery used picture sequences for this domain. It used list sorting for working memory, picture vocabulary and reading recognition for language, and pattern comparison for processing speed. Card sorting and a flanker task addressed executive function and attention.

The authors described a validation study with 476 participants aged 3 to 85, and this paper reports the data for children aged 3 to 15. Validation asks whether measures behave as intended. It does not establish that practising similar games improves those domains. freegama's games are our own implementations with their own rules. They are not the NIH Toolbox, and a game score cannot be read as a Toolbox result.

Executive functions: controlling what you do

In Executive Functions, 2013, Adele Diamond reviewed three core processes:

• Inhibitory control: resisting an automatic response or irrelevant information.
• Working memory: holding information in mind while using it.
• Cognitive flexibility: changing the rule or perspective you use.

Diamond distinguished response inhibition from interference control. Holding back a button press and answering despite distracting arrows are different task demands. Her account places planning and reasoning among higher-order functions built from the core processes.

Akira Miyake and colleagues, 2000, studied updating, shifting and inhibition in 137 college students. They used several tasks and statistical models to separate shared from distinct contributions. The processes were related but distinguishable. Their work also addressed task impurity: a task draws on processes beyond the one it is intended to examine.

That gives us a useful reading habit. Ask what else you must do to complete the task. Remembering instructions, finding a target and pressing a button can all sit inside one round.

How freegama's four skills relate

The table is our editorial mapping of task families. It is not a validated classification of freegama scores. Framework connections use the sources above; the sub-category names come from our catalog planning. Some listed families remain planned. Examples below describe games in the current catalog, without claims of transfer.

Daily skill	Connections to the frameworks	Technical sub-categories, with a plain gloss
Memory	CHC memory abilities; NIH working and episodic memory; executive working memory	Verbal short-term memory span: retain an ordered verbal list. Visuospatial short-term memory span: retain locations. Visuospatial working memory: hold and manipulate locations. Working memory updating: keep the latest information. Paired-associate learning: learn links between items. Complex span: remember while doing another task.
Focus & speed	CHC processing speed; NIH attention, speed and executive function; executive inhibition and flexibility	Selective attention: choose relevant information. Interference control: answer despite distraction. Response inhibition: withhold a response. Cognitive flexibility: switch rules. Processing speed: make simple decisions quickly. Divided attention: handle concurrent demands, as in Track the Few's multiple-object tracking. Sustained attention: maintain attention over time.
Logic & reasoning	CHC fluid reasoning and visual processing; higher-order executive reasoning and planning	Inductive reasoning: infer a pattern. Deductive reasoning: follow clues, as in Number Grid. Constraint satisfaction: satisfy puzzle rules, as in Bell Cove. Visuospatial planning: plan a route, as in Cord Garden. Concept formation: infer a grouping rule.
Numbers & words	CHC quantitative, knowledge and reading-related abilities; NIH language; executive processes when rules require them	Mental arithmetic: calculate mentally. Arithmetic verification: check a calculation. Numerical estimation: approximate a value. Approximate number system: compare quantities without exact counting. Quantitative reasoning: reason about numerical relationships. Orthographic processing: work with written word forms. Vocabulary and semantic knowledge: use meanings. Verbal fluency: produce words under a rule.

Constraint satisfaction is a puzzle-family label here. The NIH battery has no separate arithmetic domain. The table shows connections and not exact equivalents.

Use the names to understand the task

Middle Arrow shows why several labels may fit. Its current workshop sprint asks for the framed middle arrow's direction. A bent badge reverses the answer. A framed shelf selects a row, and two frames require answers in numbered order. The score is out of 1,000, with speed weights and error penalties. Interference control describes answering despite distractors; cognitive flexibility describes changing rules. Neither label turns that score into an isolated ability measure.

The newer games give other concrete examples. Number Grid requires each number once per row, column and box. Cord Garden asks for a route through every bed, visiting numbers in order. Bell Cove combines row, column, cove and no-touching rules. Track the Few asks you to follow marked moving boats. These are editorial descriptions of what players do. The frameworks do not establish benefits beyond those games.

These frameworks organise abilities, measurements and processes. They do not validate our category mapping, diagnose a player or demonstrate benefits from training. For a closer look at one task and its score limits, read our flanker introduction.