Processing Speed: Definition, Examples, and Cognitive Ability
Author: Angela Bogdanova · Published: October 12, 2026 · Editorial Policy
Research cluster: Intelligence, Reasoning & Cognitive Abilities · Written by Artificial Sapiens
Processing speed is the rate at which a person can carry out relatively simple mental operations accurately under specified conditions. In cognitive psychology, the term describes how efficiently information can be detected, compared, classified, transformed, or linked to a response. In differential psychology, it also names a broad cognitive-ability domain: people vary in how readily they complete speeded cognitive tasks, and these differences are statistically related to other measured abilities. The precise meaning depends on the task, its scoring rules, and the theory being used. NIH Toolbox and the National Academies overview of cognitive testing describe processing speed as a measurable cognitive domain.
A quick response on one task does not establish that someone thinks better in every situation. Equally, slow performance on a timed worksheet does not establish low intelligence. Processing speed is one important dimension within a wider cognitive profile, influenced by attention, perception, learned procedures, response methods, and testing conditions. This article explains the construct, gives everyday examples, examines its relationship with general intelligence and fluid reasoning, reviews assessment and developmental evidence, and considers what research actually supports about improvement.
What Is Processing Speed in Psychology?
Processing speed refers to the time needed to carry out a specified operation on information. A task may ask someone to notice a visual difference, determine whether two symbols match, retrieve a familiar association, or make a simple choice. Researchers can quantify latency, the number of correct answers within a time limit, or performance that jointly incorporates speed and accuracy. Different operations create different kinds of speed measures, so a score should always be interpreted as performance on a defined task or battery rather than as a literal measurement of an all-purpose mental clock.
The NIH Toolbox Pattern Comparison test provides a concrete illustration. Participants rapidly decide whether visual patterns are the same or different. The task minimizes elaborate reasoning yet still requires seeing the stimuli, maintaining a rule, deciding, and making a response. The national normative study shows that this form of processing-speed testing can yield useful comparative information while remaining subject to practice effects and age-related differences.
Processing speed as a psychometric ability
In psychometrics, processing speed is a latent ability inferred from regularities across multiple tasks. A latent ability is a statistical construct, not a directly observed physical quantity. A person's number of completed items is an observed score, whereas an estimated speed factor summarizes what several observed measures share. The distinction matters because an individual's performance can change with the test format, familiarity, motivation, fatigue, motor demands, or perceptual accessibility without a matching change in the underlying construct.
Cattell–Horn–Carroll (CHC) theory identifies processing speed, often labeled Gs, among its broad cognitive abilities. Its core concerns the efficient completion of simple or well-learned operations, frequently under time pressure. The placement of individual narrow factors and test indicators has evolved across CHC revisions, and the term should be read within the particular measurement model in use. CHC provides a useful classification of observed ability patterns; it does not say that every speeded task measures only one pure process. The CHC literature describes these interconnected factor structures.
Cognitive speed, mental speed, and psychomotor speed
The labels cognitive speed, mental speed, perceptual speed, and psychomotor speed overlap, but they do not always designate identical procedures. Perceptual-speed tests typically emphasize quick discrimination of symbols, images, or patterns. Decision-speed tests emphasize selecting among response alternatives. Psychomotor-speed tests involve the integrated speed of mental decisions and physical responding, sometimes with substantial fine-motor demands. Reaction-time tasks may measure a narrower interval from stimulus to response. A useful interpretation specifies the actual measurement rather than treating all speed labels as interchangeable.
Examples of Processing Speed in Everyday Life
Consider scanning a row of icons to locate a familiar symbol, quickly noticing whether two forms contain the same date, recognizing a common road sign, or matching a code to a symbol key. Each activity involves a fairly familiar or elementary operation whose completion time can vary across people and conditions. The practical consequence depends on the environment: the same person might move quickly through familiar visual comparisons but require more time when language, unfamiliar instructions, distracting material, or complex choices are added.
School and learning examples
A student may understand a math procedure and produce correct answers when allowed sufficient time, while completing fewer items on a timed sheet. Reading fluency, handwriting, symbol recognition, and familiarity with the content can all affect that performance. In another example, a learner may readily explain a scientific concept in conversation but need extra time to copy information, scan a page, or switch among visual details. These situations can raise a question about processing efficiency, yet they cannot by themselves identify which component is responsible.
A child's output during a classroom exercise is shaped by learning opportunities, language demands, anxiety, handwriting or keyboard skills, instruction quality, task difficulty, and available time. A meaningful evaluation therefore contrasts several kinds of work: accuracy on untimed problems, speed on simple operations, response modality, and whether the difficulty persists across settings. Research in a child psychiatric sample illustrates that the implications of a relatively low processing-speed score depend on general cognitive ability and the way weakness is defined. See the study on processing-speed weaknesses and functional outcomes.
Work, technology, and daily decisions
Everyday activities may require quick detection and routine classification: spotting a mismatch in data entries, comparing similar documents, locating information in a familiar interface, or sorting uncomplicated requests. But complex work also demands precision, judgment, domain knowledge, and monitoring of mistakes. A person can be methodical and highly accurate on difficult tasks while doing simple speeded operations relatively slowly. The demands of an occupation or task determine whether raw speed is useful, incidental, or less valuable than careful verification.
Driving offers a vivid illustration of interacting processes. Detecting a changing signal promptly matters, yet safe behavior also relies on attention, visual acuity, situational awareness, anticipation, response selection, and motor execution. Calling all of this processing speed would hide the distinct contributions of those systems. Real-world performance is usually multi-determined; an isolated laboratory measure gives information about one part of a broader activity, not a complete prediction of success.
How Processing Speed Works: From Stimulus to Response
A speeded cognitive task can be described as a sequence of partially overlapping stages: sensory registration, perceptual identification, attentional selection, retrieval or comparison, decision formation, response preparation, and execution. The time recorded by a test can include several stages, and their relative importance changes with the task. Some theories treat slowing as a broadly shared reduction in processing efficiency; others emphasize specific components, strategic differences, or changing task demands. There is no single universally accepted mechanistic explanation for every observed processing-speed difference.
Perception and sensory quality
A faint, low-contrast, visually cluttered, or difficult-to-hear stimulus may take longer to identify accurately. It would be a mistake to attribute all of that delay to general cognitive ability. In research with older adults, visual functioning and speed of processing have been studied as connected contributors to measured memory span and fluid intelligence. One cross-sectional structural modeling study found patterns consistent with sensory and speed-related pathways, while its design does not establish a definitive causal sequence.
Attention and decision rules
A person must direct attention toward task-relevant information and sustain the rule for responding. Distractors may create additional selection demands, and an ambiguous rule may require longer decision time. Researchers often separate simple reaction time, choice reaction time, and comparison tasks precisely because increasing the number of response options or information requirements alters the psychological operation. A slower choice response can reflect more complex evidence accumulation or deliberate caution rather than a uniformly slow nervous system.
Response selection, movement, and the speed–accuracy tradeoff
Timed tasks almost always contain a strategic tradeoff between speed and accuracy. Someone may slow down to reduce errors; someone else may respond quickly and accept more mistakes. Reporting only the number completed can conceal that difference. Handwriting, button pressing, visual scanning, or spoken output may introduce motor and modality effects. Assessment methods should evaluate errors, response requirements, accommodations, and the task's intended construct. The National Academies discussion of psychological testing emphasizes contextual interpretation of cognitive measures.
Processing Speed Within the CHC Model
In the CHC framework, Gs represents a broad ability involving speed in performing simple, often repetitive cognitive operations. This is related to, but conceptually distinguishable from, fluid reasoning (Gf), crystallized knowledge (Gc), short-term/working memory factors, and general intelligence (g). A hierarchical model expects broad abilities to correlate because cognitive tests show a positive manifold: people who score relatively highly on one kind of cognitive task tend, on average, also to do well on others. It does not make the broad abilities identical.
Some CHC formulations distinguish perceptual speed, number facility or numerical speed, rate of test taking, and other narrow components; instruments do not always sample these equally. A task that asks a person to rapidly apply learned arithmetic facts involves speed together with knowledge and number skill. A visual comparison measure draws more strongly on perception and visual-motor responding. Thus, saying a test assesses Gs is an interpretation supported by a battery's validation research, not a promise of a process-pure score.
General intelligence and cognitive speed
General intelligence, or g, is a higher-order statistical construct summarizing common variance across varied cognitive performances. Processing speed represents a partly distinguishable domain that correlates with general cognitive ability. The existence of a correlation does not establish that one causes the other or that an individual's intelligence can be inferred from how fast they complete a short matching task. A study comparing several speed tests in adults around age 70 found that many associations with later-life ability were substantially related to ability measured much earlier in life.
Processing speed versus fluid intelligence
Fluid intelligence concerns solving unfamiliar problems, discovering relationships, and reasoning when a ready-made answer has not been learned. Processing speed concerns how rapidly defined operations are performed. A difficult matrix problem may demand sophisticated reasoning even if no stopwatch is used. A symbol-matching task can place considerable pressure on quick performance with very limited reasoning demands. Their scores are associated in many datasets, especially across age, yet they answer different questions about cognition.
Processing speed versus working memory and executive functions
Working memory involves keeping information temporarily available while processing or manipulating it. Executive functions include control processes used in coordinating behavior toward goals. Processing speed can influence the amount of information handled in a fixed time, while working-memory load, distractors, and shifting rules can affect speed. A study that reports correlations between these dimensions has documented association, not an equivalence between the constructs. The NIH Toolbox validation research found stronger associations of its pattern-comparison test with other speed measures than with working-memory and language measures.
How Is Processing Speed Measured?
Researchers and practitioners use multiple task families because any one speeded measure mixes intended cognitive processes with task-specific demands. Validity requires evidence that an interpretation of test scores is appropriate for its purpose. Reliability asks how consistently scores reflect performance under defined conditions. Norms situate an observed score relative to a relevant reference sample. Neither the prestige of a test's name nor the presence of a numerical score substitutes for those forms of evidence.
Symbol search, coding, and visual comparison
Common test formats include rapidly locating a target among symbols, transcribing symbols according to a learned key, and identifying whether two images are alike. Coding may rely more on eye–hand coordination, graphomotor speed, incidental learning, and sustained repetitive output. Symbol search tends to place different demands on visual discrimination and selection. The NIH Toolbox directory also includes an oral symbol–digit format that changes response modality. Similar labels across tasks therefore do not imply equivalent sensitivity to motor, visual, or linguistic differences.
Reaction time and inspection time
In a simple reaction-time task, a person detects a stimulus and responds as quickly as possible. A choice reaction-time task adds discrimination and response selection. Inspection-time procedures can estimate how briefly information can be displayed while still being discriminated accurately, reducing some response-speed demands. These measures are useful for investigating elementary cognition but cannot individually stand for a comprehensive intelligence test. The findings of Deary, Johnson, and Starr demonstrate that distinct speed measures can relate differently to general ability and aging.
Timed scores, standard scores, and percentiles
A raw score might be the number of correct comparisons made in 90 seconds, or the median time taken for accurate responses. A standardized score transforms that observation according to a defined norm group and scoring model. A percentile describes rank within the comparison sample; it is not the percentage of questions answered correctly and not the percentage of cognitive ability a person possesses. Comparisons require knowledge of age norms, language, test version, administration conditions, and the confidence interval or uncertainty associated with the score.
The NIH Toolbox normative study involving 4,859 participants illustrates why calibration matters. The authors found developmental and age-related differences as well as a practice effect upon retesting. Its observed test–retest agreement, validity correlations, and age suitability were evaluated empirically rather than assumed. A speed score from this instrument cannot simply be converted into the score for a different brand of test, and published norms for one age band cannot be transferred without justification to another.
Why a low processing-speed score needs context
An unusually low standardized speed score means the person completed the specified test less efficiently than the reference group under the tested conditions. It can be a useful reason to explore possible contributing factors, particularly if daily difficulties are consistent and consequential. It does not automatically reveal why performance was low. Sensory conditions, fine-motor demands, medication effects, language experience, stress, sleep, motivation, task familiarity, and response caution may all be relevant to interpretation, depending on what the test actually requires.
Professionals may compare multiple speed tasks and other cognitive domains to determine whether a score discrepancy is stable, meaningful, and relevant to the referral question. A within-person relative weakness differs from a normatively low score: a very high-performing person might have a speed score lower than their other scores while still scoring above the general-population average. The implications of those patterns vary by context. Research on processing-speed weakness in youth addresses this relative-versus-normative distinction.
Is Processing Speed the Same as IQ?
Processing speed and IQ occupy different levels of description. Processing speed refers to a broad domain or a family of speeded performances; IQ is a norm-referenced score derived from a specified intelligence assessment. Some comprehensive cognitive batteries include processing-speed components, but their relative weighting and the treatment of unusual score profiles differ across instruments and editions. An overall IQ composite may incorporate information from several abilities, whereas a processing-speed index summarizes selected speed-related tasks.
A processing-speed score therefore cannot be treated as an IQ score. Nor can a single overall IQ value tell us precisely how someone performs on quick visual matching, complex reasoning, verbal comprehension, or daily activities. An isolated discrepancy should be considered in light of reliability, normative differences, and the objectives of testing. In the National Academies review of cognitive testing, processing speed is recognized as one among several domains that assessment may need to characterize.
What Does Research Show About Processing Speed and Intelligence?
Correlation is robust, but explanations are multiple
Measured speed and general cognitive ability are positively associated in many samples, but the size and interpretation of that association depend on tasks, age, and the range of abilities studied. Faster performance may help with completing more operations within a constrained time; efficient perception, attention, and retrieval may also contribute to performance on complicated tests. Alternatively, a more general source of individual differences may partly shape both speed and other abilities. Cross-sectional correlations by themselves cannot select among these causal accounts.
The Deary and colleagues study measured several speed indicators and general ability in more than 900 approximately 70-year-old participants, with a historical measure of childhood cognition. Its results complicate the idea that speed tasks provide a unique and simple biological gauge of cognitive aging. Longitudinal research also indicates that speed and other cognitive trajectories share variance, yet studies differ in the constructs measured, models, and assumptions needed to infer direction.
What longitudinal and genetic research contributes
Longitudinal designs can track how speed-related performance and other abilities change within individuals. Twin and adoption studies can partition population-level statistical variation under explicit assumptions, but such partitions are specific to samples, environments, and designs. For example, Finkel and colleagues' longitudinal twin study found shared genetic influences on processing speed and other cognitive abilities in adults. Those estimates neither imply that one person's speed is genetically fixed nor identify the causal effect of any single gene.
How Processing Speed Changes With Age
Childhood and adolescence
Speed on many elementary tasks improves substantially from childhood into adolescence as several relevant capacities develop: faster recognition of familiar stimuli, improved attention, more efficient strategies, and more fluent movement. This developmental pattern is observed in normative speed-testing studies, though the details vary by instrument and age. A large NIH Toolbox sample showed gains across successive childhood age groups and different suitability at very young ages. Age comparisons must use appropriate norms and avoid turning a developmental variation into an automatic diagnostic judgment.
Adulthood and older age
On average, many processing-speed measures become slower with advancing adulthood, whereas accumulated knowledge can remain comparatively resilient for longer. There is substantial variation among people in the timing and rate of change, and cross-sectional differences can be affected by cohort and sampling conditions. The meta-analysis of longitudinal cognitive change found that aging-related changes in several cognitive domains are moderately coupled, while individual rates and patterns vary markedly.
Explanations of age-related slowing consider perceptual changes, response strategy, motor speed, neural efficiency, and common influences on several cognitive abilities. Researchers have proposed models in which slower elementary processing constrains performance on more elaborate tasks. The meta-analytic review by Verhaeghen examines these relationships and their limitations. A statistical mediation model can fit the data while leaving alternative causal structures possible, so causal statements require stronger convergent evidence than model fit alone.
Speed change is not automatically a disorder
An expected shift in performance over the life course must be distinguished from a new, persistent, or functionally significant difficulty. A sudden or substantial change can warrant health evaluation in context, particularly when accompanied by confusion, neurological symptoms, or changes in everyday functioning. No online speed game or isolated score can determine the cause. Such questions belong to appropriate medical or clinical assessment; this article's focus is the broad cognitive ability and its scientifically supported interpretation.
What Factors Can Influence a Processing-Speed Test?
Performance depends partly on the person's relatively stable abilities and partly on immediate testing conditions. Sleep disruption, acute stress, limited familiarity with a response device, poor visibility of stimuli, hearing difficulties, restrictive time limits, motor impairments, and different approaches to error avoidance may affect outcomes. Some medications, health conditions, and mood states can also alter concentration or response behavior. The size and causal role of each influence depend on specific evidence; it would be scientifically unsound to infer a person's health or diagnosis from speed alone.
Language and cultural familiarity can become important when a supposedly simple timed task uses letters, symbols, instructions, or procedures with unequal familiarity across groups. Good test practice considers translation and accessibility as empirical measurement questions, not cosmetic issues. The same concern applies to computer use: timing recorded on unfamiliar hardware can include device-handling skill. The National Academies guidance provides a broad rationale for considering a test in the context of its actual uses.
Processing Speed, Attention, ADHD, Learning Difficulties, and Mental Health
Processing-speed measures sometimes appear in research on ADHD, specific learning difficulties, neurological conditions, and psychiatric disorders. These literatures involve heterogeneous samples and diverse instruments. A group-level association between a condition and average test performance does not make processing speed a specific marker of that condition. Different pathways can yield similar scores, and different people with the same diagnosis may have markedly different cognitive profiles. Formal evaluation considers developmental history, functional impact, multiple sources of information, and the appropriate diagnostic criteria.
Attention lapses can lengthen response times or cause missed items, but sustained attention and processing speed are distinguishable constructs. Slow handwriting may limit timed written output with preserved speed on a vocal or manual-button alternative. Difficulties with automatic symbol retrieval may affect one task family more than another. These examples show why the practical question is which process or combination of processes constrains a given activity, and what adjustments are supported by that evidence.
Can Processing Speed Be Improved?
Practice effects and task-specific learning
People often become faster at a practiced task. They may learn where to look, develop an efficient response pattern, or become more confident with the instructions. Such gains are genuine improvements in task performance, but they are not automatically evidence of an increase in a general latent speed factor. The NIH Toolbox normative research documented measurable practice effects over a short retest interval, which illustrates why training and repeated assessment must be interpreted carefully.
Near transfer and far transfer
Near transfer means improvement on tasks that closely resemble the trained task; far transfer means improvement on substantially different abilities or important real-world outcomes. These distinctions are essential when evaluating claims about brain games or processing-speed training. A second-order meta-analysis of cognitive-training research concluded that near transfer is more consistently observed while broad far-transfer effects are small or absent after accounting for research biases. The overall literature also includes interventions and populations that differ, so conclusions should name the training procedure and outcome rather than promise universal effects.
The ACTIVE trial and targeted speed training
A well-known randomized trial in older adults, ACTIVE, investigated training in memory, reasoning, and speed of processing. The ten-year follow-up report described persistence of certain trained-domain benefits and examined everyday functioning. This is meaningful evidence that some structured interventions can produce durable changes in targeted cognitive performance. It should not be converted into a claim that all commercial brain-training programs increase IQ, that improvements generalize to every cognitive domain, or that training prevents a particular illness.
Practical ways to support accurate performance
For everyday work and learning, reducing unnecessary time pressure, clarifying task instructions, minimizing visual clutter, allowing a suitable response method, and practicing genuinely relevant routines can improve performance or accessibility. These are task-design strategies, not claims of biological cognitive enhancement. Where important limitations persist, the most appropriate accommodation depends on the activity and the individual. A timed task can be redesigned to value accuracy or allow extra time when speed is not the actual skill that needs to be measured.
Processing Speed and Real-World Ability
Speed can matter when a task's purpose genuinely requires fast discrimination or response. In many other domains, real-world quality depends more on accuracy, knowledge, persistence, creativity, judgment, collaboration, or planning. The relative weight of speed is an empirical question about a particular environment. This is why a cognitive-ability score can offer useful information without defining overall competence. A highly skilled professional may prefer deliberate checking when errors are costly, while an experienced operator may become fast through domain-specific expertise.
Assessment should distinguish observed speed from the capacity to achieve a correct result with adequate time. It should also ask whether a test's motor, sensory, cultural, or language requirements mirror the situation for which decisions will be made. These are core questions of valid score interpretation. An operationally convenient timed test is not necessarily a better measure of a person's potential than a carefully chosen battery of tasks.
How to Interpret a Processing-Speed Result Responsibly
Start by identifying the exact assessment, its edition, age and language norms, and what activities produced the score. Determine whether the result is an observed raw value, percentile, standardized index, or broader latent estimate. Review reliability, confidence intervals, errors, response modality, and whether the testing conditions were appropriate. Interpret the result alongside the other cognitive domains and the referral question. Any clinical or educational conclusion should be made by a qualified professional using the broader body of evidence rather than from one subtest.
When someone reports feeling 'slow,' the first useful step is clarification. Do they mean difficulty understanding unfamiliar concepts, slow reading or writing, delayed decisions, trouble filtering distractions, fatigue, or an abrupt change in responsiveness? These experiences point to potentially different mechanisms and practical responses. The term processing speed can organize the inquiry, but meaningful assessment begins with the actual activity, its demands, the history of the difficulty, and the person's goals.
Common Misconceptions About Processing Speed
Myth: Faster always means more intelligent
Measured processing speed is one correlated component within cognitive ability research. Intelligence includes reasoning, knowledge, comprehension, and other domains, and speeded accuracy is shaped by testing conditions. A very rapid answer can be incorrect; a well-reasoned answer can take longer. General ability estimates and simple speed measures share variation without becoming interchangeable.
Myth: Slow processing means poor understanding
People may understand material accurately yet need more time to scan, retrieve, organize, write, or respond. The reverse is also possible: someone may rapidly perform familiar comparisons while struggling with a complex novel problem. A fair interpretation contrasts understanding, accuracy, time demand, and response mode.
Myth: One low score proves ADHD or a learning disorder
A low score may occur for multiple reasons. Diagnostic decisions require evidence about symptoms, history, functioning, alternatives, and relevant standards. Processing-speed performance alone is neither a diagnosis nor a reliable label for the person.
Myth: Brain games that speed up responses raise overall IQ
Practice improvements frequently reflect learning the trained task, and some interventions produce benefits on similar outcomes. Generalized improvement in intelligence requires separate evidence. The cognitive-training meta-analysis underscores the distinction between specific skill gains and far transfer.
Frequently Asked Questions
What is an easy definition of processing speed?
Processing speed is how quickly and accurately someone can perform a specified mental operation, such as matching two symbols, identifying a pattern, or responding to a familiar cue. The measured speed depends on the particular activity and response requirements.
What are five examples of processing speed?
Examples include comparing two visual patterns, scanning for a target symbol, applying a familiar symbol–number key, locating a simple mismatch in a list, and choosing between two learned responses. These examples do not all measure exactly the same narrow components.
Is processing speed a type of intelligence?
Processing speed is commonly modeled as a broad cognitive ability within CHC theory, and it correlates with other abilities and general intelligence. It is one component of a multidimensional ability profile rather than a synonym for intelligence.
Does slow processing speed mean a low IQ?
No conclusion about overall IQ follows from one speed measure. The relation depends on the assessment and the rest of the cognitive profile; careful interpretation uses test-specific norms and multiple indicators.
Is processing speed the same as reaction time?
Reaction time is a family of measures of latency from stimulus to response. Some reaction-time measures index aspects of processing speed, but processing-speed testing also includes timed visual comparisons, coding, and other procedures.
Does processing speed get slower with age?
On average, many speeded cognitive tasks show slower performance across later adulthood, but individual differences are substantial and tasks vary. A meaningful change must be evaluated in the context of health, senses, motor demands, and everyday function.
Can children have relatively slow processing speed and strong reasoning?
Yes. A profile can show relative differences among speed-related and reasoning scores. Whether such a discrepancy is meaningful depends on the instruments, measurement error, norms, and consequences for the student's actual tasks.
Can processing speed be trained?
Task-specific performance can improve with practice, and controlled trials have found benefits from some structured speed-training interventions. Broad gains across unrelated cognitive abilities cannot be assumed; near and far transfer must be measured separately.
How do psychologists test processing speed?
Common approaches include timed symbol comparison, coding, simple or choice reaction time, and pattern comparison. Psychometric interpretation depends on standardized administration, normative samples, error rates, reliability, and validity.
Should I take an online processing speed test?
An informal online game may illustrate the concept or provide feedback about that particular task. It cannot establish a clinical condition or a trustworthy standardized cognitive profile without validated norms, test conditions, and interpretation.
Conclusion
Processing speed is a meaningful domain of cognitive ability: it concerns how efficiently a person performs specified mental operations, especially under time constraints. Its scientific interpretation depends on the kind of task, how accuracy and time are combined, normative standards, and relationships with other abilities. It is associated with intelligence and cognitive aging but is neither a complete account of intelligence nor a standalone diagnostic indicator. The strongest practical approach is to define the task, examine reliable evidence, and consider the individual cognitive profile and real-world context.