What are executive
functions and how do neuropsychologists assess them with
individuals who have suffered brain damage?
In a comprehensive
review, Diamond (2013, Abstract) argues that there are three core
executive functions (EFs):
Inhibition
= (1) response inhibition (self control, resisting
temptations, resisting acting impulsively) and (2)
interference control (selective attention and cognitive
inhibition)
Inhibition
“involves being able to control one’s attention, behavior,
thoughts, and/or emotions to override a strong internal
predisposition or external lure, and instead do what’s
more appropriate or needed” (Diamond, 2013, p. 137)
Working Memory
(WM) = “involves holding information in mind and
mentally working with it (or said differently, working with
information no longer perceptually present)…The two types of
WM are distinguished by content—verbal WM and nonverbal
(visual-spatial) WM” (Diamond, 2013, p. 142)
Note that
Inhibition and WM both support each other.
Cognitive
Flexibility = creatively thinking "out of the box,"
seeing things from different perspectives, and quickly and
flexibly adapting to changed circumstances.
One aspect of
cognitive flexibility is being able to change
perspectives spatially (e.g., “What would this
look like if I viewed it from a different direction?”) or
interpersonally (e.g., “Let me see if I can see this from
your point of view”)" (Diamond, 2013, p. 149)
“Cognitive
flexibility also involves being flexible enough to adjust
to changed demands or priorities, to admit you were
wrong, and to take advantage of sudden, unexpected
opportunities” (Diamond, 2013, p. 149)
Cognitive
flexibility depends upon both Inhibition and WM
Higher-Order
EFs
Diamond (2013)
argues that three “higher-order” executive functions build
upon the core functions. These are (1) Reasoning, (2)
Problem-Solving, and (3) Planning. The notion
of “Fluid Intelligence” reflects both Reasoning and
Problem-Solving” (p. 152, Fig. 4)
Some of the approaches or methods of assessment of executive
functions by neuropsychologists are listed below. Note that
this list is selective and by no means exhaustive.
Delis-Kaplan
Executive Function System (D-KEFS, 2001)
Edith
Kaplan, Ph.D. (1924-2009) was one of the most important
pioneers in modern clinical neuropsychology. She worked in the
Boston area for her whole professional life beginning in the
1950s at Boston University's School of Medicine, the Boston
Veterans Administration Hospital, and Suffolk University. She
was widely consulted on a variety of cases, e.g., when John
Hinckley attempted to assassinate President Reagan in March of
1981, Kaplan was asked to do a full neuropsychological
assessment of the defendant (he was found not guilty by reason
of insanity for his crime, but spent over 30 years in public
hospital settings before being released in 2016). Considered
the "mother of clinical neuropsychology, the irrepressible
Edith Kaplan died at age 85 (Delis, 2010).
Dean Delis, Ph.D.
was a pre- and post-doctoral intern working with Kaplan at the
Boston VA Hospital in the 1970s and later her collaborator in
developing the D-KEFS. He worked for many years on the faculty
of the UCSD School of Medicine from which he retired. He
continues the practice of clinical neuropsychology as a
private clinician.
A nationally
standardized battery of 9 tests which evaluate a broad range
of EFs. As Patterson (2013) summarizes, the D-KEFS consists of
the following instruments which can be used either
individually or as a test battery. (Note a revised D-KEFS-2 is
under preparation, but as of October 2023 has not yet been
published).
1. Trail Making
Test (Flexibility of thinking; not the older
Trails A & B, but similar)
5 forms/conditions
Conditions: (1)
mark only the 3s, (2) connect the numbers, (3) connect the
letters, (4) connect numbers and letters numerically and
alphabetically, (5) follow the dotted line and draw a line
as neatly as possible.
2. Verbal Fluency
Test (Fluent productivity in the verbal domain)
Condition 1: given
a letter of the alphabet, name as many words (but NOT names,
places, or numbers) in 60 secs.
Condition 2: Name
as many animals in 60 sec. and, then, as many boys’ names in
60 secs.
Condition 3: Name
as many fruits and furniture in 60 sec. while switching
between two categories when responding
3. Design Fluency
Test (Fluent productivity in the spatial domain)
On a response
form, connect dots and then make as many different designs
with using only a specified number of lines
4. Color-Word
Inference Test (Verbal inhibition; based on the original
Stroop Test presented further below)
Condition 1: shown
color blocks, say the colors in order
Condition 2: shown
words, read them in order (e.g., green, red, red, green,
blue)
Condition 3: words
are printed in colors, but examines must name the color of
the ink and not the word
Condition 4: words
and words in boxes: read the word not in the boxes, but
report the color of the ink of words in the boxes
5. Sorting Test (Problem-solving,
verbal and spatial concept formation, flexibility of thinking
on a conceptual task)
Condition 1: With
6 mixed up cards (each with a word and a picture), sort the
cards into two groups
Condition 2: With
the same cards sorted by the examiner, the examinee must
identify what categorization rule was used.
6. Word Context
Test (Deductive reasoning, verbal abstract
thinking; see figure above on left)
Given a made-up
word (in context), examinee must determine what it means
10 items, each of
which has 5 clue sentences
7. Tower Test
(Planning & reasoning in spatial modality; impulsivity;
variation of the “Tower of Hanoi” task used with Patient H.M.
and others; see figure above on right)
Given rules about
the discs that construct the towers
Examinee must make
the tower and discs look like a picture in the stimulus book
Shown a page that
has 30 pictures, the examiner chooses a picture and the
examinee must ask the least number of yes/no questions to
determine what picture the examiner chose
9. Proverbs Test
(Metaphorical thinking; generating versus comprehending
abstract thought)
Condition 1:
proverbs are read and examinee asked to interpret orally
Condition 2: same
proverbs are presented, but examinee must choose among 4
options as the one which best describes the proverb.
Examples of
proverbs
"The squeaky
wheel gets the grease”
“When in Rome,
do as the Romans do”
“A bad workman
always blames his tools”
“A rolling
stone gathers no moss”
“A stitch in
time saves nine”
Some
other approaches to evaluating EVs include the following:
1. Abstract
Concepts & Shifting Cognitive Set
Wisconsin Card
Sort Test (WCST)
Originally published in 1948. An online computer version
of the test is also available.
The WCST
assesses the following executive functions (Silva-Filho
et al. 2007)
Cognitive Flexibility: The
ability to shift mental sets and adapt to changing
rules or environmental feedback.
Abstract Reasoning: The ability
to form concepts and think abstractly.
Planning and Organization: The
capacity to develop and execute a plan to achieve a
goal.
Working Memory: The ability to
hold and manipulate information in the mind, such as
the "failure to maintain set" indicator.
Perseveration: The tendency to
repeat a previous response even after the rules have
changed.
Self-Monitoring: The ability to
monitor one's own behavior and correct errors
Four “target”
cards are placed on table: 1 red triangle, 2 green stars,
3 yellow crosses, and 4 blue circles.
Examinee is
presented with a stack of cards (a total of 128) and told
to place each of them below the proper or right target
card. Examiner will only tell them if they are “right” or
“wrong”.
Examinee has
choice of category: color, number, or shape.
First criterion:
color. Then changed to number, then to shape. But, the
examinee is not told that the criterion has changed.
After the
examinee has gotten 10 correct placements, the examiner
changes the criterion to a new one.
2. Goal
Formulation (Volition [Lezak et al., 2012])
This function
refers to the ability of a person to know what s/he needs
now and will need in the future. It requires an awareness of
the self and the surrounding environments in which the
patient has to function.
Patient's family
and staff of health-care facility may prove to be very
helpful sources of information regarding issues of a goal
formation
Cookie
Thief Story from Boston Diagnostic Aphasia Exam
(BDAE)
what is happening in this picture. Is patient able to
understand the complexities of the environment and to
describe what needs to happen for both the boy and the
"mother" to respond to their current situation.
Description of card: On right side, mother is washing
dishes, but fails to see that the sink is overflowing and
the water is pouring onto the floor. On the left side behind
her back, children are stealing cookies: a boy in the upper
left is reaching into a cookie jar to give cookies to
himself and his sister who is on the lower left, but at the
same time the stool he is standing on is tipping over
Measures concepts such as
(1) visual perception in each of the four quadrants (upper
right & left; lower right & left);
(2) understanding that two different stories are happening
(to the mother at the sink and to the children at the cookie
jar); and
(3) understanding of the interrelationships between mother
& children (they are sneaking the cookies while she is
otherwise busy).
3. Planning &
Decision Making
This function
refers to the ability of a patient to determine and organize
the steps and elements (including procedures and materials)
necessary in order to carry out or reach a goal.
Porteus Maze
(simple to very complex mazes): Patient must trace the
maze without entering into any blind alleys. While
originally designed as a non-verbal test of performance
intelligence, this test shows characteristic performance
deficits in persons with brain damage including
impairments to planning, i.e.., decreased speed and
increased errors.
WISC: Mazes
Subtest
4. Purposive
Action = "Translating an intention or a plan into
productive, self-serving activity" (Lezak et al., 2012, p.
683)
Tinkertoy Test (Lezak,
1982). Subject is given a standard 50-piece collection of
Tinkertoy objects and told to build whatever they want. They
have a minimum of 5 minutes (with no upper time limit). Upon
completion, they are asked to describe what they built.
5. Impulse Control
The Stroop
Color and Word Test (SCWT) = “In the most common
version of the SCWT, which was originally proposed by Stroop
in the 1935, subjects are required to read three different
tables as fast as possible. Two of them represent the
“congruous condition” in which participants are required to
read names of colors (henceforth referred to as color words)
printed in black ink (W) and name different color patches
(C).
Conversely, in the
third table, named color-word (CW) condition, color-words
are printed in an inconsistent color ink (for instance the
word “red” is printed in green ink). Thus, in this
incongruent condition, participants are required to name the
color of the ink instead of reading the word. In other
words, the participants are required to perform a less
automated task (i.e., naming ink color) while inhibiting the
interference arising from a more automated task (i.e.,
reading the word). This difficulty in inhibiting the more
automated process is called the Stroop effect (Stroop,
1935)” (Scarpina & Tagini, 2017, p. 1)
References
Delis, D. C. (2010). Edith Kaplan (1924-2009)
[Obituary]. American Psychologist, 65(2), 127-128. https://doi.org/10.1037/a0018250
Silva-Filho,
J. H., Pasian, S. R., & Carvalho do Vale, F. A. (2007)
Typical performance of elderly patients with Alzheimer disease
on the Wisconsin Card Sorting Test (WCST). Dementia &
Neuropsychologia, 2, 181-189. https://dx.doi.org/10.1590/s1980-57642008dn10200011
Stroop, J.
R. (1935). Studies of interference in serial verbal reactions.
Journal of Experimental Psychology, 18, 643–662. https://dx.doi.org/10.1037/h0054651
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Edith
Kaplan, Ph.D. (1924-2009) was one of the most important
pioneers in modern clinical neuropsychology. She worked in the
Boston area for her whole professional life beginning in the
1950s at Boston University's School of Medicine, the Boston
Veterans Administration Hospital, and Suffolk University. She
was widely consulted on a variety of cases, e.g., when John
Hinckley attempted to assassinate President Reagan in March of
1981, Kaplan was asked to do a full neuropsychological
assessment of the defendant (he was found not guilty by reason
of insanity for his crime, but spent over 30 years in public
hospital settings before being released in 2016). Considered
the "mother of clinical neuropsychology, the irrepressible
Edith Kaplan died at age 85 (Delis, 2010). 
Cookie
Thief Story from Boston Diagnostic Aphasia Exam
(BDAE)
Tinkertoy Test (Lezak,
1982). Subject is given a standard 50-piece collection of
Tinkertoy objects and told to build whatever they want. They
have a minimum of 5 minutes (with no upper time limit). Upon
completion, they are asked to describe what they built.
The Stroop
Color and Word Test (SCWT) = “In the most common
version of the SCWT, which was originally proposed by Stroop
in the 1935, subjects are required to read three different
tables as fast as possible. Two of them represent the
“congruous condition” in which participants are required to
read names of colors (henceforth referred to as color words)
printed in black ink (W) and name different color patches
(C).