How does knowing the real reasons influence the error definition?

11 March 2019

Katarzyna Jezierska-Krupa

Senior UX Designer
Katarzyna Jezierska-Krupa
How does knowing the real reasons influence the error definition?

In what way do we interpret reality? How do we make decisions? What are the factors affecting the final product or service experience? As designers, we want to create reality, have influence on it, interact either through a project or product. Designing new products or improving existing ones has to response to some shortage or fulfill the need which has not been satisfied so far. What do we need to know to define such a deficit aptly and make our projects meet a whole range of requirements and acknowledge numerous limitations?

Looking for the answer to the above questions, I will use a device which affects a very delicate movement system in our bodies despite being quite simple in its operation. I am taking about a three-surface table for spine traction.


The idea of the device operation is trivial: to stretch a patient’s spine and eliminate tensions or pain in this way. We can do it in the cervical or lumbar section or in three axes. The three-surface table for the spine traction is used in several dozen settings in Poland, in clinics, private surgeries and rehabilitations centres. The device directly influences patient’s quality of life. However, it is imperfect (as everything in this world). I decided to find its weaknesses and define the requirements a new version of it has to fulfill in order to be safer.


Looking for mistakes I had to get to know the way the table should be used and compare it to the real state of affairs. Conducting 8 context and 4 deepened interviews helped me.

The procedure is relatively simple: a patient lies down on the bed and they are tied to it with belts (at the height of a pelvis and chest – if we stretch the cervical section also at the height of a head). Then, a physiotherapist starts the programme using a touchscreen. The patient is stretched depending the force used by the physiotherapist. After finishing the procedure, patients lay down still for about 15 minutes so that no loosened structures could be dislocated.

The physiotherapeutic device works as an element of the system which shall be understood as a group of elements, interactions and dependencies among them. The elements can be organisms, technical objects, utensils. They can also be people.

In case of a three-surface table for the spine traction the system has 3 elements. They include: a patient, a device and physiotherapist and the interactions among them – everything which takes place between a patient and device, between a physiotherapist and patient and between a device and physiotherapist.


A physiotherapist says something to a patient – the interaction takes place. A patient corrects their position on a device – another interaction. A physiotherapist ties a patient with belts – interaction again.


In order to recognise which error takes place in the system I had to examine the way the elements interact and compare these observations with a model, ideal procedure.

The mistakes I was able to recognise are numerous. They include some of these examples:

  • the programme is wrongly recorded,
  • the interface is illegible,
  • the recommendations concerning the procedure were wrongly passed
  • the belts were incorrectly fastened,
  • the patient was moving too much.

Among these incidental mistakes the designer is sensitive to, there were also intended ones, having different reasons. Each of these mistakes should be investigated separately. I would like to focus on one of them: the procedure was ended too early.

It turns out that the procedure is frequently finished too quickly and the requirement of 15 minutes of the patient’s laying still is not respected.

Why does it happen?

‘I make a mistake and I want to make it’

Two reasons of finishing the procedure too early can be mentioned:

  • while the physiotherapist is absent, patients themselves decide to stand up knowing that the active part of the procedure came to an end,
  • a physiotherapist consciously decides about finishing the procedure.

The second reason is definitely more frequent and somehow more intriguing. Why does the therapist being responsible for the patient’s health take the risk of causing their harm? Can that be justified? Can it be repaired?

Cause and solution

Let’s approach the problem and search for the solutions in an ordered way. Firstly: we need to define the mistake cause. In this case, the reason could be determined unambiguously as the physiotherapist’s wrong decision.

Being aware of the reason for the mistake we can define the requirement which the product needs to fulfill in order to avoid the error. Since a physiotherapist makes the wrong decision consciously, the project challenge which has to be placed before our product would be to make finishing the procedure too early impossible. Therefore, there is one step only to achieve the solution.

As designers we have to make it impossible to finish the procedure too quickly, influencing the system through the device. We can block the device in such a way that the procedure cannot be ended: via the mechanical blockade or programme. We can add some kind of an alarm or monitoring. As a matter of fact, the solution seems banal. The problem is it will not work.

Making it impossible for people to act according to their will, we sentence ourselves to the situation when nobody chooses our solution. Is there anything we can do, then? Or maybe we are in the tragic situation without any good solutions?

Getting to know

In our system the key elements are people who are subject to different factors not belonging to the physiotherapeutic system: they are affected by colleagues, weather, sleepless night, a delayed train etc. People do not always act in the same way and they have different motives. It is easy to assess their decisions hastily.

If we can affect our system elements, then it is worth understanding how each of them works, what motives they have and understand the context of their actions. It is the context in which the system operates and the influence of the system higher levels on its work which is the basis of eliminating its mistakes. Therefore, we have to analyse the interactions of our system elements with external systems. If we look at the problem with the same limitations all the time, we will not notice anything new.

Reasons need to be sought outside the system

If a physiotherapist makes a mistake, let’s consider the reason for it. Why does he do it? Each system is the element of a higher-level system. The physio-therapeutical system is the element of the system constituted by the unit where the procedure is conducted. The institution in turn belongs to such systems as the National Health Service, legal or political ones. A patient is not only the element of the physio-therapeutical system but also family, social, work team or road traffic ones. Depending on the context, the systems can be multiplied and interactions investigated endlessly.

New definition of the project problem

Let’s consider what directly affects a physiotherapist since it is their actions we want to exert the influence on using our product. We need to understand why they undertake such decisions and no other ones. In order to do it, we have to analyse what has an impact on their actions. Our research results can be surprising!

It can turn out that: ‘I know, I make a mistake and I want to make it’ will turn into: ‘I know I make a mistake but I have no other choice’.

What was found in this case? The physiotherapist had to perform the procedure within 15 minutes because of a large number of patients and workload. After that time, they had another patient. If a given physiotherapist has to serve 4 patients within 1 hour, then the process is shortened wherever it is possible.

Having this knowledge, let’s get back to our definition of the project problem. An initial definition of the project requirement – ‘making finishing the procedure earlier impossible’ – will not work here. A new problem has to be defined as ‘making it possible to start another procedure after 15 minutes’.

How to solve it? I have got my own idea but I will give you some space for creativity 😉


To sum up, I would like to leave you with the answers to two very important questions.

What can we affect as designers?

We communicate with each other through what we create. Everything which interacts, direct contact with our project is what we are able to create.

What should we get to know while designing?

Apart from what we can have influence on, we have to get to know other forms of impact on our system elements (especially those invisible at first sight) – only this will let us understand what we really deal with and which needs and problems our project answers to.