Psychological tests:

1. There are perhaps thousands of psychological tests. The main categories of test that concern us here could be divided into:

• a) Cognitive tests
• b) Scales to measure symptoms (or personality)
• c) Structured assessments 
  • i. Diagnosis
  • ii. Semi-structured tools for assessing capacity
• d) Neurological tests

• a) Cognitive tests

2. The term ‘cognitive’ has become much more widely used in the last few decades – both within academic psychology and general circles. It applies to those psychological tests that cover thinking abilities rather than personality, temperament, emotions, attitudes, etc. Cognition is usually further subdivided into ‘cognitive functions’ or faculties, such as memory, attention, perception, language, etc. 

3. Intelligence (or intellectual) or IQ tests are usually based on a collection (or ‘battery’) of such tests (ie., ‘sub-tests’). It is sometimes useful to look at these measures separately – for example to show that an individual has a particular weakness (or strength) in one or another.

4. An IQ is a summary measure of such tests with the additional step of ‘standardisation’ – which in this context refers to a statistical procedure which converts the final score of different tests so that the average (mean) for the population is 100; two thirds fall within 85-115 and almost everyone falls within a statistically defined ‘normal range’, between 70-130.

5. Some of the individual tests have been designed to be used in particular clinical populations where say, memory or the ability to use language, has been lost due to a brain injury or illness (eg stroke) or altered development. These are sometimes called ‘neuropsychological tests’. They may therefore start with items that a healthy person should find very easy but may go up to really difficult ones which even a healthy person would struggle with. Neuropsychological tests sometimes have cut-off scores of “normal/abnormal”; some have accompanying ‘norms’ – usually in the form of reference tables and some, ideally, have this broken down into age bands.

6. Most neuropsychological tests and all standard IQ tests – for example the Wechsler Adult Intelligence Scales (WAIS, in various editions) should be administered by a suitably trained and registered psychologist (either a clinical psychologist (including neuropsychologist) or educational psychologist). This ensures that the tests are done in a near identical way and scored according to strict rules.

7. A more recent term is “neurocognitive”. Adding ‘neuro-’ in front of a test is sometimes done in order to make it seem more ‘scientific’ or somehow more directly tapping into the brain or nervous system. This is redundant because all cognitive tests or indeed psychological tests must surely be tapping into what the brain does. Where else in the body does thinking take place?

8. Sometimes, some tests, particularly those used to estimate IQ, are referred to a ‘psychometric’. This refers to subfield of psychology which is particularly concerned with measures and measurement across populations and has a strong statistical leaning. But the word can be used more broadly to refer to any test which yields a quantitative score.

9. There are important caveats around any kind of cognitive test such as the influence of language, educational opportunities and culture, which may lead to erroneous estimates. 

10. There are several tests or rating scales which are intended to be used by clinicians from different backgrounds with minimal specific training and which provide a quick and easy “screen” [1] A screening test is strictly speaking one designed to be used in the general population to pick up likely cases – usually so that they may undergo further testing. of ability. An example is the Mini Mental State Exam (MMSE). This is scored out of 30 and includes simple questions for the testee about the day and date, where the person is, some words to remember, pronounce, arithmetic and so on. This is a widely used scale for people with dementia and a score of <24 is generally taken to be indicative of possible dementia.   Other cut-offs for moderate and severe dementia have been suggested with ‘severe’ being <10.  As regards IQ, a score of <70 is said to indicate mild intellectual disability, with cut offs defined for moderate and severe down to <20 which is classed as ‘profound’.

11. A correlation (a statistical index of how related two measures are) between measures like IQ or MMSE on the one hand and some other index or judgement of capacity on the other, may be calculated by researchers. A correlation may be strong – i.e. a low MMSE score corresponds reliably to impaired capacity. However, correlation estimates are based on groups of individuals and are rarely perfect – there is usually some variation that remains unaccounted for. This means it is difficult to apply a correlation index to individual cases and even if such an attempt were to be made, it would necessarily lack specific context (‘the matter’ in respect of which a decision is required).  

12. There is therefore no ‘test score’ that coincides with the presence/absence of capacity, especially, but not only, because capacity should be considered in relation to a particular decision.  So a prediction based upon a score is not a substitute for case by case justification, which must be based upon functional assessment.  Even where the score is very low, and the prediction might be highly accurate, there must still be a legal justification given focusing on the legally specified functional abilities. 

13. Most examples of contested capacity occur when the individual has a level of general intellectual ability that is not self-evidently severely impaired. Indeed they may have an average or even good level of IQ but their suspected disorder of brain or mind is subtle and unevenly spread (see below).

Executive Function

14. We have discussed above, tests or collections of tests designed to give a general overview of a person’s thinking abilities while noting in passing that such abilities can intuitively be divided into faculties or functions.  The notion of executive function has arisen most strongly, especially in the clinical sphere, in relation to people who (following a brain injury or disorder) perform reasonably well on these individual tests and may even score highly overall on an IQ or similar score and yet their behaviour seems to be seriously impaired or defective. This has been dubbed paradoxical. The paradox may be explained by a deficit in the coordination and application of these subsidiary functions (as though by an executive sitting in an office upstairs controlling their underlings) which motivate and enable the individual to plan and work out a strategy, to foresee the consequences of their actions, to take into account pros and cons, to find creative solutions to problems, etc. Hence losing these ‘higher’ superordinate abilities is bound to disable a person, particularly when living in a complex environment. Simplifying greatly, the part of the brain thought to house the executive functions is the frontal lobe. 

15. There are a number of specifically designed tasks intended to test executive function (eg the Wisconsin Card Sorting test) which are claimed to pick up damage to the frontal lobes (hence frontal lobe tests are sometimes used as a synonym for executive function tests). The real world is somewhat messier than this implies. People with diffuse brain damage frequently fail ‘frontal lobe tests’ and those with definite, focal damage to the frontal lobes (eg following surgery) may be unimpaired. Some tests have been designed to closely mirror the sort of commonplace but nevertheless complex tasks of everyday life (such as shopping) and they occasionally reveal striking failures despite good scores, on other even ‘executive’ tests.

16. Another cluster of abilities which go beyond both basic cognitive faculties and executive functions is the ability to track and think about states of mind – both our own and other. Thinking about others is called social cognition. This includes the innate and unconscious ability to empathise with feelings and emotions in others, to sense social rules and intuit others’ intentions and the conscious ability to think about other people’s thoughts. Clearly a deficit in this realm will have serious consequences, particularly upon friends and family. Thinking about ourselves is known as metacognition and includes being able to detect whether or not one has made a mistake, that one’s memory has failed or perception is suspect. These abilities are again often found wanting by people whose decision-making capacity has been questioned. Failures of metacognition (as well as social cognition and executive function) are likely to result in conflict because of the differing perspectives of the individual and his/her circle. The impaired ability to detect that one’s thinking is flawed or one’s perceptions or view of the world are at-odds with other peoples’, falls squarely under our definition of metacognition but where the posited explanation for those flaws is a mental or neurological disorder, the term ‘lack of insight’ is frequently applied.   See further in this regard the section on insight

“Talking the talk but not walking the walk…”

17. The above description, more formally, a discrepancy between stated or intended behaviour and that which is observed, is frequently noted in contested capacity cases. This can arise through lack of insight into… or a metacognitive impairment such that the individual is unable to accurately detect their own difficulties. This may be broken down as a preserved ability to recognise rules and limitations in the abstract or the ‘here and now’ but genuine inability to foresee eventualities or to apply the rules. Another formulation of this phenomenon is as a failure to update one’s self-appraisal of ability in the light of a recent problem – essentially a memory deficit. The issue may shade into more qualitative and less obviously ‘cognitive’ domains such as a person’s relative indifference to the consequences of actions (even if they are foreseen) or a disregard of the need to be consistent or to be honest with others. This can be framed as an executive dysfunction, ‘organic personality change’ or problem of social cognition (plausibly so if it is ‘out of character’) but could equally be viewed through a moral/ethical lens: the person is ‘being selfish’ or ‘lying’, etc. One conclusion from this discussion is that it is not only permissible but desirable, if indeed not vital, to supplement an individual’s account with observations over time, recorded previous behaviour and other collateral information when evaluating whether a person has or lacks capacity to make a specific decision.      And, as set out in the body of the guidance note, and in the NICE guideline on decision-making and mental capacity, it is always necessary for the final conclusion to be reached as to whether the person has or lacks capacity to make the decision by reference to the actual test set out in the MCA 2005.   In other words, it is never appropriate for a conclusion to be reached that a person has or lacks capacity to make a decision on the (sole) basis that (for instance) they have impaired executive capacity.  

• b) Scales to measure symptoms (or personality)

18. There are a number of ‘psychological’ scales or inventories – collections of a set questions covering a theme or construct – used in psychological research and practice. These can cover anything from mood (eg depression), stress, anxiety, attitudes, experiences (eg hearing voices), behaviours (eg impulsivity), substance dependence, and so on. Those that aim to draw out enduring traits or temperament may be called personality tests or scales. They may be self-reporting or part of a structured or semi-structured interview (the latter enabling a degree of interpretation). As with cognitive tests they may have designated cut-offs for “normal”/”abnormal.” Their advantage is in reducing the variability in the way constructs are defined or the way questions are worded. They provide a summary or score which can be compared with other individuals or groups or within the same individual across time (to show improvement or decline). Such scales may be used by many health professionals as an adjunct to their work in assessing clients. Medically qualified personnel, particularly senior ones tend to use them least – partly through habit but also because they feel that their skill lies in individual interpretation and this trumps uniform formats.

19. Providing a score on say the Beck Depression Inventory (BDI) – a tried and tested self-report depression scale has some value and is widely understood. However describing in a few sentences a précis of a person’s account of their mood – their hopes, fears, beliefs – qualified with everyday descriptions, without numbers attached can be more compelling, particularly in a legal setting.

• c) Structured assessments

• i. Diagnosis

20. Structured assessments in this context are protocols with example probe questions and with an algorithmic structure. As with the scales described above, the main motivation for these is to minimise heterogeneity in the nature and quality of assessments. Some are designed to make or exclude a particular clinical diagnosis (eg autism spectrum disorder) although a degree of expertise, interpretation and training is still required. 

• ii. Semi-structured tools for assessing the functional abilities relevant to capacity

21. Some authors have attempted to give structure to assessment of decision-making capacity by giving guidelines or a format for practitioners—or more often, researchers of capacity—to follow (eg the ‘MacArthur’ suite of competence assessments). They may be focussed on say, financial or treatment decisions. These have the advantage of making sure all elements of the capacity definition are covered by the assessor and provide useful framing questions which may be applied in particular contexts. 

22. However, these are only aids or tools and do not by themselves (say, by some cutoff score) generate capacity judgements since a determination must be made whether a certain level and type of impairment—even if reliably and validly measured as a matter of degree—is sufficient for decisional capacity. This is because of several reasons. First, the highly individual nature of the matter in question means that there will not be evidence-based norms to provide a valid cutoff score. Second, whether someone does or does not have capacity to make a specific decision will depend on contextual factors that may vary from situation to situation. Third, the final judgment that a certain degree of intact functional abilities is or is not sufficient for capacity is a ethico-legal (i.e., normative) and not a scientific (i.e., factual) question. 

• d) Neurological Tests – including neuroscientific measures and brain scans:

23. Technological advances enable the structure and function of the brain to be studied and displayed in exquisite detail.  Damage, disease or maldevelopment to the brain may be visualised which provides the context for discussions about capacity, even at the level of an individual case.  But a person can have a normal looking brain and yet still have an impairment of mind or brain and be seriously lacking in decision making capacity and alternatively, have widespread evidence of brain damage or dysfunction and yet demonstrate ample capacity. Physiological measures such as the electroencephalogram (EEG) are central to the diagnosis of epilepsy and can be used to indicate awareness in people with impaired levels of consciousness. The debate around “neuroscience in the court room” is complex and constantly evolving with many ethical and technical elements but is outside of the scope of this note.

24. Nevertheless, some generalisations can be made based on our current understanding. There is no reliable or valid ‘signature’ of incapacity on any brain scan or investigation. MRI and CT brain scans are very helpful in the diagnosis of eg., dementia but, especially in the early stages, need to be interpreted in the light of other clinical information. Changes in brain structure and function within ‘psychiatric disorders’ such as autism and schizophrenia (or psychosis) is the topic of intense research but at the time of writing, little routine clinical application. That is, not all impairments of the mind or brain will be detectable by these tests.

25. Measuring brain activity during decision making (using for example functional MRI (fMRI)) is another area of academic research which usually aggregates patterns within groups rather than individuals. It may point to regions of the brain most active during particular cognitive functions which might imply that damage in those areas would impair decision making but this is by no means necessarily the case. In particular, the potential for neuroplasticity, learning and the “multiple realizability” of mental function (i.e. there are different ways of thinking that can all lead to solving a problem) means that knowing the location of damage or disease within the brain is typically not sufficient to infer cognitive, executive or social function.

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