Analyzing Concept Formation with Colour Sorting Tests

When a psychologist places a handful of coloured wool skeins in front of you and asks you to group them, the task sounds almost childishly simple. But what happens next – and more importantly, how flexibly your mind responds when the grouping rules silently shift – reveals something far more complex about how you think. Colour sorting tests are among the oldest and most revealing tools in psychodiagnostics, designed to measure not just what you perceive, but how you categorize, generalize, and mentally reorganize the world around you.

What are colour sorting tests? 🔗

Colour sorting tests are a category of conceptual thinking assessments that require individuals to organize objects – traditionally skeins of wool or coloured blocks – based on a shared visual attribute, such as hue or brightness. Unlike tests that rely on language or numerical ability, these assessments tap into a person’s capacity for non-verbal abstract reasoning. The participant is asked to select a skein of their preference and then identify all other skeins that can be grouped with it. According to neuropsychological assessment literature, most sorting tests of this kind are designed to assess not just the ability to use a concept, but crucially, the ability to shift between concepts when the criteria change.

The core intellectual demand is twofold: first, the participant must identify an organizing principle (for example, grouping by warm hues); second, and more diagnostically significant, they must abandon that principle and switch to an entirely different one (such as grouping by brightness or saturation). This switching requirement is what makes colour sorting tests powerful indicators of higher cognitive function.

The cognitive skills these tests measure 🔗

Concept formation 🔗

Concept formation is the cognitive process of recognizing shared features across distinct stimuli and grouping them under a common category. Research on concept formation experiments describes it as the act of learning to categorize specific experiences into broader rules or categories – the mental work that allows us to go beyond individual instances and recognize general patterns. In colour sorting tests, a participant who groups deep reds, oranges, and yellows together is forming and applying a concept of “warm colour.” That ability to extract and apply a rule from perceptual information is the hallmark of abstract thought.

Cognitive flexibility and set-shifting 🔗

Perhaps the most clinically significant skill assessed by colour sorting tests is cognitive flexibility – the capacity to shift mental strategies when situational demands change. According to ScienceDirect’s overview of sorting-based neuropsychological assessments, mental flexibility requires the capacity to shift a course of thought or action according to rapidly changing situational demands. When a participant is asked to re-sort the same skeins by brightness after having sorted them by hue, they must suppress the previously successful strategy and generate a new one. Difficulty doing this – a phenomenon known as perseveration – is a significant clinical marker. Perseveration means continuing to apply an old rule even when it is no longer correct, and it is consistently associated with impaired executive functioning and frontal lobe dysfunction.

Abstract versus concrete thinking 🔗

Colour sorting tests also probe the boundary between abstract and concrete thinking. A person thinking concretely may group skeins only by exact colour matches (this one is precisely the same red as that one), whereas abstract thinking allows grouping by broader conceptual similarity (these belong together because they share brightness regardless of hue). Research by Tamkin and Kunce found that the inability to shift conceptual attitude on sorting tasks is consistent with cortical dysfunction, and that poor performance appears to reflect dysfunction in symbolic reasoning rather than spatial reasoning alone.

The Weigl Colour-Form Sorting Test: a closer look 🔗

One of the most widely used instruments in this tradition is the Weigl Colour-Form Sorting Test (WCFT), developed by Eduard Weigl in 1927. It presents participants with 12 coloured geometric blocks and requires them to sort these pieces by colour, and then shift to sorting by form – unassisted. A study published in the Journal of Psychiatric Research notes that the test requires patients to sort the pieces and then shift to the other sorting principle without being guided, making the demand for self-initiated cognitive switching central to the task.

Clinically, the WCFT has proven to be a useful, non-verbal bedside screening tool. A study published in International Psychogeriatrics, conducted with 236 subjects including stroke survivors, Parkinson’s disease patients, and healthy controls, found that the WCFT demonstrated good sensitivity and specificity in detecting cognitive impairments across all groups. The researchers concluded it is a practical adjunct to existing cognitive screens in clinical settings.

Further research has confirmed that the Weigl is particularly sensitive to frontal lobe damage. A study in Neuropsychological Rehabilitation found that a significantly greater proportion of patients with frontal lesions failed the Weigl compared to those with non-frontal lesions, and that failure was specifically associated with patients repeating the same sorting solution twice – a direct sign of perseverative thinking. Importantly, this performance was not explained by differences in fluid intelligence, meaning the test measures something distinct from general IQ.

Wool skeins and brightness: the nuance of the original test 🔗

In the classical wool-skein version of the colour sorting test, the task begins by asking the participant to choose a skein they prefer and then select all others that “go with it.” This initial choice already reveals something: does the person sort by hue (the actual colour family – red, blue, green), by brightness (how light or dark a colour is), or by some other property altogether? The shift from sorting by hue to sorting by brightness is not trivial. Hue and brightness are separate dimensions of colour perception, and moving between them requires the participant to mentally disengage from one perceptual attribute and engage a different one. This is a cognitively demanding act of controlled attention and flexible categorization.

Research published in Visual Cognition confirms that colour-concept associations influence fundamental processes in cognition, including object recognition and visual reasoning, and that these associations are learned and generalized through experience. This means that performance on colour sorting tasks is not merely a matter of colour vision acuity – it reflects the depth and flexibility of a person’s learned conceptual frameworks.

Relationship to broader sorting tests 🔗

Colour sorting tests belong to a wider family of sorting-based assessments in neuropsychology. The most famous of these is the Wisconsin Card Sorting Test (WCST), developed by Grant and Berg in 1948. The WCST requires participants to sort cards according to shifting rules – colour, then shape, then number – without being told when the rules change. It has been used extensively since the 1960s to assess frontal lobe dysfunction, and according to its publisher, it is particularly useful for identifying difficulties in initial conceptualization, perseveration, failure to maintain cognitive set, and inefficient learning.

The Delis-Kaplan Sorting Test (ST) is another related instrument designed to provide separate measures of initiation, concept formation, problem-solving, and cognitive flexibility as distinct constructs. What unites all these tools is the fundamental insight that how a person sorts – and especially how they respond when the sorting rules change – is a window into the efficiency of their executive functions.

Clinical and diagnostic significance 🔗

Colour sorting tests and their variants are used across a broad range of clinical contexts. They are deployed in the assessment of dementia, where impaired concept shifting is an early indicator of declining executive function. They are also used in evaluating patients with schizophrenia, where perseverative errors on sorting tasks are a well-documented cognitive feature. Research in Applied Neuropsychology has demonstrated that sorting-based tests are sensitive to the executive function deficits associated with substance use disorders, detecting impairments in cognitive flexibility and abstract reasoning that are characteristic of these conditions.

Beyond neurological and psychiatric populations, sorting tasks are also valuable in educational and developmental assessment. A child who can sort by one rule but cannot shift to another may not yet have developed the executive control needed for tasks that require flexible problem-solving – a skill critical for academic learning and adaptive behaviour in everyday life.

Why colour, specifically? 🔗

Colour is a natural choice for sorting assessments because it is a salient, pre-attentive feature – humans process colour rapidly and without conscious effort. This makes colour a perceptually accessible anchor for sorting tasks. However, it also means that colour can become a dominant attentional anchor, making it harder to disengage from hue-based sorting and shift to a less salient attribute like brightness. Earlier work on the Weigl test noted that individuals with organic brain damage tended to show a preference for sorting to colour – suggesting that colour-based classification may represent the more concrete, default mode of categorization, while shifting away from it demands higher-order cognitive control.

This makes colour sorting tasks particularly elegant from a diagnostic perspective: the very property that makes the initial sort easy is what makes the subsequent shift challenging. The test effectively uses the mind’s own attentional habits against itself to expose the flexibility – or rigidity – of conceptual thinking.

What do you think? If you were asked to sort objects by colour and then immediately by brightness, do you think you would find that shift easy or surprisingly difficult – and what might that reveal about how your mind organizes information? Considering that colour sorting tests can detect early signs of cognitive decline, how important do you think non-verbal assessments like these are compared to traditional verbal intelligence tests in clinical diagnosis?

References

1. https://psylearners.psychotechservices.com/2016/08/ignou-corner-solved-assignments-mpce012_23.html
2. https://www.studocu.com/en-us/document/creighton-university/bachelor-of-arts-honours-course-psychology/3-concept-formation-full-experiment/92170401
3. https://www.sciencedirect.com/topics/neuroscience/wisconsin-card-sorting-test
4. https://journals.sagepub.com/doi/abs/10.2466/pms.1982.55.1.105
5. https://www.sciencedirect.com/science/article/pii/S0887617707002211
6. https://pubmed.ncbi.nlm.nih.gov/17245801/
7. https://pubmed.ncbi.nlm.nih.gov/32772947/
8. https://www.tandfonline.com/doi/full/10.1080/13506285.2022.2089418
9. https://en.wikipedia.org/wiki/Wisconsin_Card_Sorting_Test
10. https://www.wpspublish.com/wcst-wisconsin-card-sorting-test
11. https://pubmed.ncbi.nlm.nih.gov/31060391/
12. https://www.researchgate.net/publication/13507723_Validation_of_a_New_Scoring_System_for_the_Weigl_Color_Form_Sorting_Test_in_a_Memory_Disorders_Clinic_Sample