What You Need To Know About DKEFS (Delis–Kaplan Executive Function System)

What is the Delis-Kaplan Executive Function System?

Dean Delis, Edith Kaplan, and Joel Kramer spent a decade creating the Delis-Kaplan Executive Function System. This state-of-the-art system has transformed how clinicians assess executive functioning across different populations since its publication in 2001 ^[1].

Origins and development of the D-KEFS

The story of D-KEFS began in the early 1990s. Dean Delis created a sorting test to study patients with focal frontal lobe lesions and classic amnesia syndrome ^[2]. His original research led to discussions with the Psychological Corporation about creating a complete battery of executive function tests. The project aimed to include Edith Kaplan’s process approach.

The team ended up creating the first nationally standardized tests to assess higher-level cognitive functions in children and adults ^[3]. They co-normed D-KEFS with the original Wechsler Abbreviated Scale of Intelligence (WASI) ^[2]. This gave clinicians complementary tools to get a full picture of cognitive abilities.

The D-KEFS brought something new to the table – multiple switching conditions. Delis pointed out that tests like the Trail Making Test and Wisconsin Card Sorting Test mainly assess switching and cognitive flexibility ^[2]. The D-KEFS built on these classic measures and added new ways to assess executive functions.

Purpose and target populations

Psychologists needed a complete tool to assess various executive functions. The D-KEFS filled this gap by measuring cognitive flexibility, problem-solving, conceptual reasoning, inhibition, multitasking, and nonverbal and verbal creativity ^[4]. The battery looks at four main areas:

1. Cognitive flexibility
2. Response inhibition
3. Planning
4. Concept formation and reasoning ^[5]

The D-KEFS stands out with its over 1,500 individuals norm group that matches U.S. demographics and regions ^[6]. The sample covers ages 8 through 89 years, making it suitable for both children and older adults ^[6].

Clinical settings benefit from this assessment tool. It excels at finding mild brain damage in the frontal lobes and shows how deficits in higher-order thinking affect a person’s functioning ^[1]. The D-KEFS results help create targeted coping strategies and rehabilitation programs.

Schools also find the D-KEFS valuable as it complements standard intelligence and achievement tests ^[1]. The assessment helps with various clinical conditions including frontal-lobe lesions, attention deficit hyperactivity disorder, specific learning disabilities, mood disorders, autism spectrum disorders, traumatic brain injury, fetal alcohol syndrome, neuroinflammatory disorders, and spina bifida ^[1].

The cognitive process approach

The “cognitive process approach” makes D-KEFS unique among executive function tests ^[4]. Instead of just giving overall achievement scores, it looks at error types, strategies, and processes to provide deeper insights ^[2].

Examiners can create and assess clinical hypotheses by comparing performance across different testing conditions ^[3]. Contrast measure scores and detailed error analyzes help identify why someone might struggle with specific tasks ^[4].

To name just one example, the D-KEFS Trail Making Test expands from two trials to five trials (Scanning, Numbers, Letters, Number-Letter, and Direct Processing Speed) ^[5]. This change increases processing demands and can reveal the root cause of task completion issues.

On top of that, the D-KEFS includes “capture stimuli” in tests like the Sorting Test. Here, examinees sort based on words (verbal strategy) or perceptual features (nonverbal strategy) ^[2]. The D-KEFS creates separate subscores for different abilities rather than combining them into one score.

Despite some concerns about certain D-KEFS measures’ psychometric properties, especially reliability ^[7], more clinicians and researchers choose this system. They value its integrated approach to executive function assessment.

The Nine Subtests of the D-KEFS

The Delis–Kaplan Executive Function System (DKEFS) assessment battery has nine different subtests. Each subtest targets specific aspects of executive functioning. The cognitive process approach helps assess particular executive skills and provides multiple measures to identify why performance deficits occur.

Design Fluency Test

The Design Fluency Test measures problem-solving behavior initiation, pattern generation fluency, and creative thinking. Participants must create new designs by connecting dot arrays with four straight lines. The test looks at three key skills: creating new designs, following task rules, and stopping repetition of previous responses.

Research shows that creating new designs (first two trials) relies mostly on motor planning and producing new motor actions, while drawing speed plays a secondary role. The switching trial relies heavily on visual scanning and visual-attentional resources. The test aims to measure cognitive flexibility, yet research reveals this skill doesn’t substantially affect performance on any of the three D-KEFS Design Fluency trials ^[8].

Color-Word Interference Test

Built on the prominent Stroop paradigm, the Color-Word Interference Test assesses the ability to inhibit dominant and automatic verbal responses. Four conditions make up the test, with inhibition and inhibition/switching trials being the toughest.

Standard data suggests the inhibition/switching trial should be harder than the inhibition trial. Clinical observations show that all but one of these patients 57.1% show an unusual pattern and perform better on the inhibition/switching trial ^[9]. These patients usually show slower performance on simple color naming and word reading tasks.

The Color-Word Interference Test shows promise as an embedded measure of performance validity. A cutoff score of ≤18 on combined age-corrected scaled scores from all four conditions best detects invalid performance in non-demented samples ^[10].

Sorting Test

The Sorting Test evaluates concept formation, categorization skills, and cognitive flexibility. Participants must sort cards based on various perceptual and verbal concepts and explain their sorting principles.

Two phases make up the test: free sorting where participants create their own sorts, and sort recognition where they identify the examiner’s sorting principles. The test measures attempted sorts, confirmed correct sorts, description scores, and perseveration.

Research comparing traumatic brain injury (TBI) patients with controls revealed notable differences in all five Sorting Test variables. This highlights how well it detects executive dysfunction. The D-KEFS Sorting Test might work better than the Wisconsin Card Sorting Test at finding perseverative responses and set-maintenance difficulties in TBI patients ^[11].

Twenty Questions Test

The Twenty Questions Test assesses abstract reasoning and concept formation. Participants identify a target item from 30 line drawings using the fewest yes/no questions possible. Success depends on good categorization strategies rather than asking about single items.

The test measures Weighted Achievement score, Initial Abstraction score, and Total Questions asked. Researchers suggest adding Total Abstraction Score (TABS) and Learned Abstraction Score to better capture abstract reasoning abilities throughout the test ^[12].

Patients with prefrontal lesions ask substantially more questions than controls, often using all 20 questions. A closer look shows these patients use poor categorization strategies and tend to ask about single items instead of broader categories ^[13].

Word Context Test

The Word Context Test evaluates verbal modality, deductive reasoning, and integration of multiple information pieces. This subtest looks at how well someone can figure out word meanings from context clues, which needs hypothesis testing and flexible thinking.

The Consecutively Correct Score serves as the main achievement measure, showing how quickly participants identify target words. The test works well remotely since it only needs verbal responses to written stimuli ^[14].

Tower Test

The Tower Test assesses spatial planning, rule learning, and inhibition of impulsive responses. Participants move disks of different sizes across three pegs to build specific tower patterns. They must follow rules – smaller disks go on larger ones, and only one disk moves at a time.

Studies show the Tower Test resists intentional response bias, suggesting it might also withstand things like fatigue or symptom exaggeration ^[15]. Factor analysis shows three distinct components: first-move time, excess moves, and rule violations – each measuring different aspects of executive function ^[16].

Understanding D-KEFS Scoring Methods

The Delis–Kaplan Executive Function System (D-KEFS) uses a detailed scoring system that gives clinicians multiple levels of data to interpret. This system helps them learn about executive functioning better than traditional single-score tests.

Primary measures vs. contrast scores

D-KEFS creates two main types of scores: primary measures and contrast scores. Primary measures are summary scores that show overall test performance. These scaled scores have a standardized mean of 10 and a standard deviation of 3 ^[17]. Clinicians can use these scores to compare performance between different subtests and people.

Contrast scores give a more detailed analysis by comparing tests that need different executive function skills. You get these scores by taking the completion-time scaled score for simple tasks away from the scaled score of complex executive function tasks ^[18]. The Color-Word Interference Test lets you calculate a contrast score by comparing the Inhibition condition with the simpler Color Naming condition.

Contrast scores help identify specific cognitive problems. A contrast scaled score between 8 and 12 shows equal performance across tasks. Scores of 13 or higher mean better performance on executive function tasks compared to simple component tasks. Scores of 7 or lower indicate worse performance on executive function tasks ^[18].

You should be careful when interpreting contrast scores. Studies have found that many D-KEFS contrast scores are unacceptably low in reliability. Some research suggests that “the majority of D-KEFS contrast scores should be considered to be uninterpretable” ^[19]. This happens because contrast scores have two sources of measurement error instead of one in a simple score ^[19].

Process scores and their significance

D-KEFS also offers process scores that calculate the strategies people use to finish tasks. These scores give percentile ranks that show performance strategies ^[20] and explain the thinking processes behind them.

Process scores work especially well for certain groups. Children with ADHD or Tourette syndrome show more intrusion errors on CVLT-C learning trials even when their total scores match the control group ^[21].

Research on D-KEFS optional process scores shows mixed results about executive dysfunction sensitivity. A study of 35 optional D-KEFS scaled scores and percentiles found no big differences between children with ADHD and typical children ^[22]. Primary summary scores might work better than process scores to identify executive dysfunction in some groups.

Performance patterns become clearer with process scores. The Verbal Fluency test might show a child doing poorly in the first 15 seconds but fine afterward, which points to an initiation issue rather than verbal fluency problems ^[1].

Interpreting scaled scores

D-KEFS creates scaled scores with a mean of 10 and a standard deviation of 3 ^[23], following standard psychometric rules. These scores help clinicians compare someone’s performance to others their age from the normative sample of over 1,500 people ^[24].

Reliability values matter when interpreting D-KEFS results. Only about 17% of reliability values in the D-KEFS manual go above 0.80 ^[3]. This might show the challenges of measuring executive functions rather than problems with the test’s validity.

Software makes interpretation easier. The official computerized scoring assistant from the test publisher helps streamline the process ^[3]. Free software by Crawford et al. from 2011 helps spot unusual performance patterns compared to normal populations ^[3].

Clinicians should look at D-KEFS results as a whole by checking patterns across subtests instead of focusing on single scores. This integrated approach matches the test’s cognitive framework and gives the most useful insights into executive functioning.

Administration Requirements and Procedures

The Delis-Kaplan Executive Function System (DKEFS) needs proper administration. You must pay attention to examiner qualifications, testing conditions, and time management. A standardized process will give a reliable picture of someone’s executive functioning capabilities.

Qualifications needed to administer the D-KEFS

D-KEFS administrators must have a Level C qualification. This reflects how complex the test is and what it takes to interpret it. People who use this tool should have a doctorate in psychology, education, or related fields ^[25]. These advanced requirements will give a valid interpretation of results through accurate scoring.

Examiners must have:

• Detailed knowledge of neuropsychological assessment principles
• Understanding of executive function constructs
• Familiarity with standardized testing procedures
• Skills to interpret age-based scaled scores

Practitioners should stick to professional best practices and their ethical codes while giving this assessment.

Testing environment considerations

The testing environment can affect assessment validity by a lot. Traditional in-person testing needs a quiet, well-lit space without distractions. The examiner must create conditions where the person taking the test can do their best.

Telepractice administration needs extra attention:

• You’ll need high-quality audio and HD video ^[26]
• Computer screens must be 15″ or larger diagonally ^[27]
• Both parties should use an over-the-head, two-ear stereo headset with attached boom microphone ^[28]
• The test-taker’s room should be distraction-free with closed blinds to cut glare ^[27]

Some test-takers might need a trained helper. Clinical guidelines say, “For younger children, older adults, and individuals with significant neurological or psychiatric disorders, a trained facilitator will likely be needed” ^[27]. The examiner should plan for this ahead of time and note it in their report.

Time requirements for complete assessment

Time management plays a vital part in D-KEFS administration. The full battery takes about 90 minutes ^[29]. This can change based on how fast someone works and their cognitive abilities.

The battery includes nine tests. Six of them are timed: Trail Making Test, Verbal Fluency Test, Design Fluency Test, Color-Word Interference Test, Sorting Test, and Tower Test ^[30]. Each subtest has its own time limits. The Verbal Fluency Test gives 60 seconds for each trial ^[1].

Many examiners pick specific subtests instead of running the whole battery. Research shows that “Clinicians can use the D-KEFS test in a flexible manner and are free to administer any or all of the following tests” ^[7]. This lets them tailor the assessment to each person’s needs.

Examiners should record anything unusual that might affect the test results. This includes connection problems during telepractice, outside distractions, or other issues that could change how someone performs ^[26].

Psychometric Properties of the D-KEFS

Research into the psychometric properties of the Delis-Kaplan Executive Function System shows both strengths and limitations that clinicians need to keep in mind when they interpret assessment results.

Reliability across different populations

The D-KEFS shows varying reliability in its subtests and populations. The Sorting Test has moderate to high internal consistency for all age groups. Free sorting condition coefficients range from .55 to .86, while sort recognition condition values fall between .62 and .81 ^[5]. Test-retest reliability remains moderately stable for the free sort condition (r = .51) across all ages. This number drops slightly (r = .49) for the 8-19 age group, likely due to the small sample size (n = 28) ^[5].

Studies of alternate-form reliability reveal moderate coefficients for free sorting (r = .59), sort recognition (r = .72), and total confirmed sorts (r = .60) ^[5]. In spite of that, Crawford et al. raised concerns about reliability, noting that many D-KEFS measures, especially contrast scores, might have unacceptably low reliability ^[2]. Yes, it is worth noting that only about 17% of reliability values in the D-KEFS manual exceed the .80 threshold that experts typically want to see in clinical measures.

Validity studies and findings

Recent studies back up the D-KEFS’s ability to detect executive dysfunction. Research with traumatic brain injury (TBI) patients showed they scored lower by a lot on several D-KEFS measures, including:

• Trail Making Test
• Color Word Interference
• Color Word Switching
• Letter Fluency
• Verbal Fluency Category Switching ^[31]

The D-KEFS showed a clear relationship between test scores and TBI severity. It successfully distinguished between TBI, orthopedic, and normative participants with large and moderate effect sizes ^[31]. Mental processing speed affected D-KEFS performance, so clinicians should factor this into their interpretation ^[31].

Normative data and limitations

American age-adjusted norms might not fully account for demographic variables in other cultures. Norwegian researchers found major differences between D-KEFS norms and their newly developed Norwegian standards ^[32]. US D-KEFS norms proved inaccurate for Norwegian participants with high or low education levels, particularly women ^[6].

Greek researchers have also adapted the test for their population. They standardized the Color-Word Interference Test and Trail Making Test specifically for Greek users ^[33]. Age emerged as the key predictor of performance in these studies. Education level came in as the second most important factor for most Trail Making Test conditions ^[33].

The D-KEFS offers valuable clinical insights in many populations. However, clinicians should stay aware of its measurement limitations and take demographic factors into account when interpreting results.

Comparing D-KEFS to Other Executive Function Assessments

The D-KEFS and other neuropsychological measures show key differences in their methods, usefulness, and limits. Clinicians need this knowledge to pick the right assessment tools.

Traditional executive function tests vs. D-KEFS

Research shows traditional executive function tests like the D-KEFS work better than newer measures that aim for real-world validity. Studies that matched D-KEFS against the Multiple Errands Structured Test (MSET) found D-KEFS did a better job predicting daily living activities in older adults living in communities ^[34]. The results challenged common beliefs – MSET showed no edge over D-KEFS despite its apparent real-world relevance ^[34].

The D-KEFS Tower Test and Tower of London (TOL)(DX) tell an interesting story. Patients scored similarly on both tests, but the results overlapped by just 22% ^[35]. This means these tests measure different aspects of executive function, even though they look similar on the surface ^[36].

Advantages of the D-KEFS approach

D-KEFS stands out from traditional measures in several ways:

• Processing demands: D-KEFS tasks ask more from the brain. The classic Trail Making Test has two trials, while D-KEFS has five trials to give a better picture of performance issues ^[7].

• Co-norming: D-KEFS subtests were tested together on a big national sample. This lets doctors compare results across different tests – something standalone tests can’t offer ^[37].

• Detection sensitivity: Complex D-KEFS tasks can spot mild brain damage that simpler tests might miss ^[3].

Limitations compared to other assessments

D-KEFS isn’t perfect. Only 17% of reliability scores in the D-KEFS manual hit the preferred 0.80 mark for clinical tools ^[3]. The test’s design as standalone units means there are no combined scores, which limits full evaluation ^[38].

Scientists question whether D-KEFS really works better than simpler tests ^[2]. Research found “the clinical advantage of using the D-KEFS over more traditional measures is not empirically compelling” ^[2]. The test might not have enough medium-difficulty items to tell patients apart effectively, even though it fixes floor and ceiling effects.

D-KEFS offers detailed executive function assessment with many practical benefits. Yet doctors should keep its measurement limits in mind when choosing tests for specific patient groups.

Conclusion

The Delis-Kaplan Executive Function System shows some limitations in reliability values and composite scoring. Yet its detailed approach to executive function assessment proves valuable in clinical practice. The system’s nine unique tests and cognitive process methodology help clinicians spot subtle executive function deficits that basic measures might overlook.

The system works well with many population groups thanks to its standardization across a large, representative sample. Some cultural restrictions exist in international settings. The system excels at separating various neurological conditions through a detailed assessment of frontal lobe dysfunction.

Healthcare professionals need to consider both advantages and drawbacks when choosing assessment tools. DKEFS provides sophisticated evaluation capabilities, but success largely depends on proper test administration in standardized conditions. Clinicians who understand these subtle aspects can get the most diagnostic value from the assessment while staying aware of its limitations.