1. Long Liu, Uvo Hoelscher Muenster University of Applied Sciences
Evaluation of Graphical Symbols Used in ICU Comprehension among Users in Germany and in China
Long Liu, Uvo Hoelscher
Muenster University of Applied Sciences

2. Muenster University of Applied Sciences
students
12 faculties
Faculty of Engineering Physics
Biomedical Engineering Group
Centre of Ergonomics and Process Design in Healthcare
Use-Lab GmbH
Affiliated institutes
USA
China
Japan
Cooperations Projects

3. Motivation of the project
Symbols are widely used due to their advantages:
They transfer information without language barrier
They occupy less space on devices
They provide information more quickly and direct than text
Problems with symbol application:
Too many symbols may cause confusion
Some symbols may be difficult to learn, remember or understand
Even standardized symbols may be misunderstood
How are symbols validated before use
Medical personnel complains about symbols
Misunderstanding of safety-related symbols may result in additional risk

4. Symbol application on medical devices
According to ISO and EN , all use-related risks should be analyzed and controlled
Although many efforts (e.g. standardization) have been exerted to improve symbol application on medical devices, there are examples where users obviously are confused and add descriptions

5. Purpose of the study
Comprehension of some frequently used IEC symbols
Influencing factors on symbol comprehension
Intercultural aspects on symbol comprehension, e.g. China, Germany and Canada / USA
Evaluation method (e.g. influence of context information, etc.)

6. Criteria for effective symbol application
Noticeability
If a symbols can be noticed by target users
Legibility
If a symbol is legible (under all context conditions, for all target users)
Comprehensibility
If a symbol can be comprehended correctly by target users
Learnability
If a symbol can be learnt easily

7. Methods to evaluate symbol comprehension
Typical tasks that the participants conduct:
Matching a symbol to a specified meaning (matching test)
Choosing a correct meaning of a symbol (multiple choice)
Freely guessing the meaning of a symbol (open-ended free “definition”)
Presentation ways:
Symbol presentation using electrical media or on paper
Symbol presentation with or without time limit
Symbol presentation without any context, or with context in form of text, drawn picture, photos, etc.
Evaluation criteria:
The correct responses and the incorrect responses of the participants
Execution time
Subjective valuation like response certainty or user satisfaction

8. Methods suggested by ISO 9186:2001
The comprehensibility judgment test is NOT a test to evaluate the comprehension of the symbols but a test to evaluate the judged comprehensibility of the symbols. In the test a concept and a symbol are presented to the participants. They are asked to judge the percentage of the target population which would understand the meaning of the given symbol without problems.
The comprehension test is a test to evaluate the comprehension rate of the participants of the symbols. In the test the participants are presented with some symbols and are required to express the meaning (the response) of these symbols.

9. Method used in the study
Open-ended comprehension test
Free answer while global context is presented by photo. Global context shows the general workplace where a device with the symbol is typically used
Free answer while global and fine context are presented by photo. Fine context shows a device with the symbol

10. Evaluation criteria (ISO 9186: 2001)
Each response is assigned into one of 7 categories:
Correct understanding of the symbol is certain (estimated probability of correct understanding over 80%)
Correct understanding of the symbol is very probable (estimated probability of correct understanding between 66% and 80%)
Correct understanding of the symbol is probable (estimated probability of correct understanding between 50% and 65%)
The stated meaning is the opposite to the assigned
Any other response except: “Don’t know”
Response: “Don’t know”
No response

11. Evaluation criteria: scoring
Method suggested by ISO 9186:2001
Final score for the comprehensibility of a symbol:
100 % of category 1 (correct understanding certain)
+ 75 % of category 2 (correct understanding very probable)
+ 50 % of category 3 (correct understanding probable)
- 100 % of category 4 (stated meaning opposite)
= Final Score

12. Test
Symbols tested
13 from IEC 60878
3 from frequently used medical products
Participants were doctors or nurses. Participants had extensive experience with medical devices being marked with the such symbols.
Test has been conducted in their working locations
Participants in Germany
20 from intensive care department / OR
Participants in China
13 from intensive care department / OR

13. Selected symbols
Symbols with * are from manufacturers, the others are from IEC 60878

14. Category of symbols
Pictorial Abstract
ICU/OR General

15. Test material - Symbol with context
Global context
Fine context
answer: Global context
answer: Fine context

16. Results – ICU / OR (Germany)
Mean (with global context) = 42,7%
Mean (with fine context) = 52,3%

17. Results – ICU / OR (China)
Mean (with global context) = 32,2%
Mean (with fine context) = 48,2%

18. Conclusions - 1
Average comprehension of symbols is poor in both countries
RISK ASSESSMENT for symbols used to establish an ESSENTIAL REQUIREMENT is recommended
Some symbols may be evident for designers but may not evident for users
Fine context is essential for comprehension of those symbols that have lower comprehensibility

19. Results - Germany vs. China (ICU)
General symbols
Specialized symbols
Germany
China
Global context
Fine context

20. Results - Germany vs. China (ICU)
Abstract symbols
Pictorial symbols
Germany
China
Global context
Fine context

21. Conclusions - 2
Differences in comprehension performance in Germany and China are not significant
Work experience has more influence on comprehension performance than cultural difference (general symbols are more frequently used, so they are better comprehended)
Pictorial symbols are much better comprehended than abstract symbols

22. Symbol evaluation by ISO 9186:2001
Rather subjective;
Difficulties to exactly assign responses to category 1-3;
The assignment between category 3 and 5 is not always clear;
The formula for the final scores should consider category 5
The formula for the final scores should checked
Evaluation process is not efficient.