There was an interesting piece in Nature this week
(1,2) about cognitive biases in complex problem solving. The research psychologists asked subjects to
solve problems of varying complexity and structure from the perspective of
whether additional structures or steps were necessary or whether an optimal
solution could be obtained by subtracting structures or steps. I will briefly
describe each of the problems in the table below (pending permission to use one
of their graphics).
|
Task |
Description |
|
Abstract grid task |
Transform a grid
pattern to make it symmetrical |
|
Suggested changes to
a large public university |
Changes to improve
the sense of community, enable student learning, and prepare students for a
lifetime of service |
|
Lego block structure |
Improve the 8 or 10
block structure |
|
Lego block structures |
3 possible structures
built from 12 blocks of a pool of 24 blocks on a 6” x 8” base. |
|
Lego block structure |
Revision of original
structures made from a possible 20 blocks to make a 10 block structure |
|
Lego block structure |
Modify a Lego
structure so that it can hold a brick over the head of an action figure in
the structure |
|
Read and summarize an
article |
Make a 6-8 sentence
summary and then edit it to a shorter version |
|
Read and summarize an
article |
Edit someone else’s
summary and edit it to “omit needless words” |
|
Day trip to
Washington DC |
Inspect a trip
itinerary and suggest changes to improve it |
|
Make a grilled cheese
sandwich |
Make a grilled cheese
from 27 ingredients - |
|
Modify a soup recipe |
From 5, 10, and 15
ingredient soup recipes – modify from a list of ingredients and modify to
improves the soup. |
|
|
|
Inspection shows that the cognitive tasks cover many
domains ranging from 2D and 3D visuospatial tasks, language tasks, and more theoretical
tasks that involve speculative rather than confirmed outcomes. The authors suggest
an all-encompassing definition: “the cognitive science of problem solving
describes iterative processes to imagining and evaluating actions and outcomes
to determine if they would produce an improved state.”(p. 258). They define subtractive transformations as
fewer components than the original and additive transformations as more
components than the original. The
authors noted a bias in anecdotal literature to making conscious subtractive
transformations and that suggested to them that strategy may be less common or undervalued.
Across all experiments, the tendency toward subtractive
strategies with the general instruction were lower but probabilistic. For example, across all experiments,
subtractions ranged from 21-41%. A
second set of conditions with subtle subtraction cues increased the rate of
subtractive transformations to 43-61% across the same experiments. At one point the researchers added a cognitive
load task that was basically a distractor to use more attentional resources. In
these conditions cognitive shortcuts are less accessible. Under those
conditions subjects failed to identify a subtractive solution more frequently. The authors also studied subjects form Germany
and Japan suggesting that there is cultural generalizability of the additive
over subtractive strategies.
The authors consider that the differences could be
accounted for by generating a number of additive and subtractive ideas and selecting
the additive or they simply default to the additive. They elected to look at the default to the
additive mode. They describe heuristic memory searches allowing for the timely
access of relevant information. They
suggest a number of reasons what additive strategies may be favored including –
the processing may be easier, semantic biases such as more being better,
cognitive biases may favor the status quo or less change, and it may be more
probable that additive rather than subtractive changes offer a better outcome.
This is an interesting paper from a number of perspectives. First, it presents a cognitive psychology
approach with no purported biological mechanisms. There are no functional
imaging studies or brain systems described. The theories and design of experiments depends
on a psychological model of cognitive function. Second, the model is probabilistic. Although the title suggests systematic
overlooking of subtractive strategies, it turns out that many don’t and this bias
can be modified by experimental conditions such as subtraction cues. Third, the
effect of increased cognitive load can be demonstrated to increase the likelihood
of additive rather than subtractive biases. Fourth, the biases extend across a
number of domains including physical, social, and intellectual. Fifth, the
authors suggest that there may be a number of “cognitive, cultural, and
socioecological reasons for favoring the additive bias over the subtractive one. Sixth, although the additive transformation
was more likely to occur that does not mean it offers the best solution to the
problem. It may simply be the most
commonly used solution.
Real world experience illustrates how the additive
transformations can be reinforced.
Advertising is a common one. The goal of advertising is basically to sell
someone something that they don’t need or change their preferences for
something that they do need to a different product. If it works, it is an additive strategy on
top of additive behavior. If the product
being sold affects other learning centers in the brain like reward-based
learning that can lead to further additive effects. The photo at the top of
this post illustrates another example. This
kitchen drawer for spoons and spatulas is a solution to the cooking problem of
how many are needed to accomplish what the cook in this case needs to
accomplish. The drawer is packed to the point where it barely closes and at
that point, the cook is forced to reassess and decide about cleaning the drawer
out and starting over. Homeowners often
forced to make similar downsizing or subtractive decisions after 20-30 years of
additive ones and being forced with either space constraints or a smaller family.
What about medical and psychiatric treatment? I don’t think there is any doubt that additive transformations are operating. Most treatments that involve medication have a step approach with the addition of medications for symptoms that do not respond or partially respond to the initial treatment. This occurs after an explicit subtractive bias or at least a bias to maintain the status quo 20 years ago. At that time, hospitals and clinics were reviewed based on criteria to limit the amount of polypharmacy defined as more than one drug from the same class. Today, polypharmacy is common. Reference 3 below gives an example of polypharmacy defined as 5 or more medications taken concomitantly and hyper-polypharmacy was defined as 10 or more medications taken concomitantly in a 3-month sample of 404 geriatric patients with cardiovascular disease admitted to a hospital during 3-month period. They found the prevalence of polypharmacy was 95%. The prevalence of hyper-polypharmacy was 60%. Most patients (77.5%) also had a potential drug-drug interaction. Their suggestion be vigilant is a strategy discussed as being potentially successful in containing the additive strategies (2).
From psychiatry, I am including a common problem that I encountered
as a tertiary consultant. That problem
is what to do about a person with a depression that has not responded to high
dose venlafaxine. There are geographic areas in the US, where very high dose
venlafaxine is used with and without pharmacogenomic testing. From the options listed in the diagram it is
apparent that there are 4 additive (black arrows) strategies and 2 subtractive
(red arrows). There is a robust literature on the additive strategies and not
so much with the subtractive. As a result, it is common these days to encounter
patients who have tried numerous combinations right up to and including “California
Rocket Fuel” (4) of the combination of an SNRI like venlafaxine with
mirtazapine. The ways to analyze this
situation, especially if there has not been any improvement are significant and
depend a lot on patient preferences and side effects in addition to the lack of
response. I have found that very high dose venlafaxine, can be sedating to a
significant number of people and that they feel better when it is tapered. I have also seen many people far along the
augmentation strategies when tapering or discontinuing the venlafaxine was
never considered. In some of these cases, the patient reports that venlafaxine
is historically the only antidepressant that has worked for them in the past.
That brings up the issue of additive versus subtractive
biases on the part of the patient. We have all been bombarded by pharmaceutical
commercials suggesting the best way to mood stabilization is adding another
medication – typically aripiprazole or brexpiprazole. In fact, those
commercials speak directly to additive biases. It is often very difficult to
convince a person to discontinue or reduce a medication that they have talked
for years – even when careful review suggests it has been ineffective or
creates significant side effects.
Could a discussion of additive versus subtractive
transformations be useful in those situations? There is currently no empirical
guidance, but these might be additional experiments to consider for both prescribing
physicians and the patients they are seeing. Certainly the expectations that
they patient has for any given treatment needs to be discussed and whether that
expectation is reasonable given their personal experience and the objective
evidence. On the side of prescribing physicians, it is fairly easy to flag
medication combinations that are problematic either from the perspectives of
too many medications being used at once, physical and side effects not being
analyzed closely enough, or medications being changed too frequently. Would
discussing additive and subtractive strategies be useful in that setting? Would a discussion of basic rules to address additive biases such as discontinuing a medication when it is replaced be useful?
Remaining vigilant that there are subtractive strategies
out there is a useful lesson from this paper. Physicians are aware of the concept
of parsimony and how that can be applied to medical care. Given the fact that
the additive strategies are probabilistic and modifiable with conscious strategies
– that should still prove to useful in containing polypharmacy.
George Dawson, MD, DFAPA
Supplementary:
Another common additive strategy that I have encountered in
the past 10 years is performance enhancement. The patient presents not so much for
treatment of a psychiatric problem but because they believe that adding a
medication or two or three will improve their overall ability to function. Common
examples would include:
1. Presenting for
treatment of ADHD (with a stimulant medication) not because of an attentional
problem but because the stimulant creates increased energy and the feeling of
enhanced productivity.
2. Presenting for
treatment of insomnia in the context of drinking excessive amounts of caffeine
in the daytime and the caffeine is viewed as necessary to enhance energy at
work or in the gym. In some cases,
stimulants are taken in the daytime and the idea is that the medication for
insomnia would counter the effect of stimulants or caffeine taken late into the
day.
3. Taking anabolic
androgenic steroids (AAS) and expecting to treat the side effects of mood disturbances,
insomnia, anger, and irritability in order to keep taking the AAS. Many AAS users also take other medications
for this purpose as well as various vitamins, supplements, and stimulants to enhance
work outs.
4. Taking excessive
numbers of supplements with no proven value and seeking to use medications for
nondescript symptoms associated with the supplement use. In many cases,
patients with psychiatric disorders are sold on elaborate mixtures of minerals
and supplements with the promise that they address their symptoms. In many cases it is difficult to determine if
the associated vitamins and supplements interact with the indicated medical
treatment or not.
All of these are additive strategies with no proven
value that I have seen in the outpatient settings. It is obviously important to know if the
patient being treated is using these strategies. There are often competing considerations –
for example does the patient have a substance use disorder and are substance
use disorders another predisposing condition to additive biases (I suspect they
strongly are).
References:
1: Meyvis T, Yoon H. Adding is favoured over
subtracting in problem solving. Nature. 2021 Apr;592(7853):189-190. doi:
10.1038/d41586-021-00592-0. PMID: 33828311.
2: Adams GS, Converse BA, Hales AH, Klotz LE. People
systematically overlook subtractive changes. Nature. 2021
Apr;592(7853):258-261. doi: 10.1038/s41586-021-03380-y. Epub 2021 Apr 7. PMID:
33828317.
3: Sheikh-Taha M, Asmar M. Polypharmacy and
severe potential drug-drug interactions among older adults with cardiovascular
disease in the United States. BMC Geriatr. 2021 Apr 7;21(1):233. doi:
10.1186/s12877-021-02183-0. PMID: 33827442; PMCID: PMC8028718.
4: Stahl, SM .
Essential psychopharmacology: neuroscientific basis and practical
applications. Cambridge University Press, Cambridge 2000. p. 363.
