Cognitive ability and intelligence

What are core models of intelligence? 

Spearman’s g, cattel: fluid vs crystallised intelligence, Carroll's 3 –stratum theory and Cattell-Horn-Carrol (CHC) theory. 

What is Spearman’s G? 

1 factor where everything comes together in terms of intelligence. 

In Cattell’s: fluid vs crystallised model, what is fluid intelligence? 

Novel task, abstract is reasoning, identifying patterns, conceptual relationships, doesn’t rely on preexisting knowledge 

In Cattell’s: fluid vs crystallised model, what is crystallized intelligence?

Dependent on knowledge, vocabulary and past experiences, crystallised increases when we get older. 

What is CHC? 

What is CHC? 

Combines several factors. Dominant framework for understanding intelligence. Doesn’t treat intelligence as one thing, but as a structured system of abilities. Hierarchical in nature: stratum, III is general intelligence (g), stratum II is broad abilities, stratum I is narrow, specific skills.  

What does stratum II in the CHC include? 

Fluid reasoning (Gf), crystallized knowledge (Gc), working memory (Gwm), processing speed (Gs), visual processing (Gv), auditory processing (Ga), and reaction time (Gt). 

What is a practical implementation of some aspects of CHC model? 

WISC-V 

What are the Wechsler tests and what are they used for?

WISC-V (6-16), WAIS-IV (16-90), WPPSI (2-7), WAIS-II (6-90, abbreviated scale). Used for clinical diagnosis, educational placement and research. They are standardised, norm-referenced tools, not absolute measures. 

What are the index scores of the WISC-V?

Full scale IQ (FSIQ), verbal comprehension index (VCI), Visual spatial index (VSI), fluid reasoning index (FRI), working memory index (WMI), processing speed index (PSI). 45-65 minutes to administer. 

What is the FSIQ? 

total score representing general intellectual ability, 

What is VCI? 

measures verbal reasoning and knowledge

What is VSI?

evaluates spatial processing and visualisation

What is FRI? 

tests the ability to identify underlying conceptual rules

What is WMI?

measures short-term memory and attention 

What is PSI? 

assesses speed of visual information processing 

What are the subtests of the WISC-V? 

Similarities (verbal reasoning), block design (visual-spatial), matrix reasoning (fluid reasoning), digit span (working memory), coding (processing speed). 

How are similarities tested? 

Child presented with 2 words that represent common objects/concepts and describes how they are similar: ‘in what ways are_ and_alike?’ Relates to Gc, CHC ability. 

How is block design tested?

Child uses red and white blocks to recreate a design within a specified time limit. ‘you try it and make sure it looks like the picture. Go ahead.’ Relates to Gv CHC ability. 

How is matrix reasoning tested?

The child looks at an incomplete matrix and selects the missing portion from 5 response options. ‘look at these pictures, which one here goes here’. Relates to Gf CHC ability. 

How is digit span tested? 

Forward – the child repeats numbers in the same order as presented aloud by the examiner. Backward – the child repeats numbers in the reverse order of that presented aloud by the examiner. “I am going to say some numbers. Listen carefully, and when I am finished, say them straight after me. Just say what I say.”. “Now I am going to say some more numbers, but this time when I stop, I want you to say them backwards. If I say 8-2, what would you say?”. Relates to Gwm CHC ability. 

How is coding tested? 

Child copies symbols that are paired with simple geometric shapes or numbers. Using a key, the child draws each symbol in its corresponding shape or box within a specified time limit. Relates to Gs CHC ability. 

How is symbol search tested? 

Child scans a group and indicates whether the target symbol matches any of the symbols in the search group within a time limit. Relates to Gs CHC ability. 

What is administration for WISC like?

Standardised instructions, 1-1 testing, rapport matters but is constrained.

What is scoring for WISC like? 

Raw scores -> scaled scores -> composite scores. Norms based on age. Scores are relative to population, not absolute ability. Key concept is deviation IQ. Mean = 100, SD = 15. 

What are the index scores for the WAIS-IV?

Verbal comprehension (VCI), perceptual reasoning (PRI), working memory (WMI) and processing speed (PSI). All get combined to give full scale IQ (FSIQ).

What is included in the verbal index?

Similarities. ‘how are a law and a custom alike?’ 

How is matrix reasoning different to the WISC? 

More complex patterns

How is digit span different from the WISC? 

Longer sequences/higher load 

How is coding different from the WISC? 

Same structure but faster expectations, greater emphasis on efficiency 

What are strengths of these tests? 

Profile for cognitive strengths/weaknesses. Useful for: diagnosing learning differences, identifying support needs, clinical assessments, neuropsychology, research. 

What are limits of these tests? 

Snapshot in time only (validity issues?), context-dependent, doesn’t capture: creativity, practical intelligence, social cognition. 

What are critical perspectives or debates about these tests? 

Cultural/socioeconomic bias – language heavy, familiarity with test format, education access. Interpretation problems, labelling, stability/malleability, ecological validity/diagnostic validity. 

What was Marinopoulou et al 2024 

Tested whether wechsler intelligence scales predict academic achievement/grades in children aged 6-16 years with ADHD and/or autism. Reviewed 12 studies and meta-analysis of 6 studies. Correlations between 1Q and word reading, written language and mathematics. FSIQ was associated with academic achievement in both ADHD and ASD groups, and with grades in ADHD groups. High diagnostic validity across subscales for identifying gifted vs non-gifted children. Limited diagnostic validity for identifying children with ADHD – only PSI. 

What are these tests measuring? 

Performance reflects ability and also time pressure, language and cultural knowledge, anxiety and motivation. Intelligence tests shape how individuals are understood. The same cognitive profile can be interpreted in very different ways depending on context, expectations, knowledge. Over reliance on a single score risks oversimplifying, misclassifying or missing strengths.