A Pilot Study Evaluating the Comprehensibility of Graphical Symbol: Potential Impact on Aging Population and Its Implication
Xin Feng
User Experience R&D, Lexmark International
ABSTRACT
Graphical Symbols are widely used on consumer products today. With the upcoming aging trend in our society, there is a strong need to validate whether these symbols can be well comprehended by the aging people. A pilot study was deployed online to evaluate four graphical symbols. The study includes 140 subjects, with 26 of them over 65 years old. The study aims to understand how the age of subjects may influence their comprehension of graphical symbols. It follows the judgment test procedure specified in ISO (International Standard Organization) 9186 standard. The results show that for all graphical symbols with different comprehensibility level, the subjects of age group 65+’s comprehension level is always the lowest. This finding confirms that the aging population has lower comprehension level on graphical symbols. It suggests that the evaluation/usage of graphical symbols should pay particular attention to the aging people and people with special needs. A large-scale study including more symbols should be conducted to generalize the conclusion from this study.
KEYWORDS
Ergonomics, graphical symbols, accessibility, aging population, standard
BACKGROUND
Well-designed graphic symbols can be ideal visual interface components which use little space but communicate sufficient information independent of language [1]. Compared to text, symbols can be more distinctive, more efficient and easier to recognize, and more accessible to people with special needs due to limited vision, illiteracy, or inadequate knowledge of the language used by the text. Because of these advantages, graphical symbols have been widely used in Information and Communication Technology (ICT) for both consumer and professional products [2].
In spite of these features of graphical symbols, it is recognized that text describing a function in the user’s native language is generally understood more reliably than a graphical symbol [3]. The advantages of symbols listed above can only be achieved when the concept being represented by the symbol is well understood, concrete and including a small amount of details. Prior research studies also showed that while some symbols were highly comprehensible, others were poorly accepted [4]. The challenge of implementing generically comprehensible symbols may impose access barrier for end-users, particularly for certain population such as aging people. With the background of aging trend in main industrialized countries, for example, one out of every eight Americans are 65 years or older [5], it emphasizes the importance to evaluate the comprehensibility of graphical symbols with particular attention to age factor, to further understand the potential impact of graphical symbols’ usage on aging population.
Several test protocols including judgment test, comprehension test and multiple-choice test, which are setup to evaluate the comprehensibility of graphical symbols, have been standardized by national/international standards [6, 7] and validated by numerous research studies [8]. Of these protocols, the judgment test involves showing respondents the graphical symbols together with the intended meaning and the context in which the symbol might be used, and asking them to estimate for each symbol what percentage of the general population would understand it correctly. It is simpler to administer and easier to score comparing to other protocols.
In summary, there is a strong need to evaluate the comprehensibility of graphic symbols, particularly by the aging people, to better understand the usability/accessibility implication of using graphical symbols. The findings from this research study may gain more insight of general principles for the design and evaluation of generically accepted, meaningful graphical symbols.
METHOD
Objectives
This study seeks to evaluate how age of subjects may impact their comprehension of graphical symbols, with the specific aim being:
Specific aim 1:
Evaluate the comprehensibility of different graphical symbols;
Specific aim 2:
Evaluate the influence of users’ age on their comprehension of different graphical symbols with various comprehensibility levels.
Participants
As shown in Table I, 140 U.S. subjects participated in this pilot study in four age groups, with 26 out of them over 65 years old. Each group of subjects was matched with their genre and education level. All subjects were healthy, experienced office equipment users who never took similar graphical symbol research study previously, which ensured that their estimate would not be biased by their previous experience.
Total Subjects |
Age Group |
Genre |
||||
18-30 |
31-50 |
51-65 |
65+ |
Female |
Male |
|
140 |
14% |
33% |
34% |
19% |
41% |
59% |
Test Protocol and Data Analysis
Fig. 1: Tested Graphical Symbols (Click for larger view) Four graphical symbols representing “Fax”, shown in Fig. 1, were used in this pilot study as the testing symbols. The study, following the judgment test procedure specified by ISO 9186: 2007, was conducted in the form of a web-based survey. The study started with an instruction page with a completed test example, followed by demographics page which collected the demographics information such as the subjects’ age, genre, education level and so on; at the end, the test page showed the four graphical symbols with the intended meaning (“fax”) and the usage context (“which is often shown on an office equipment or computer program”), and then asked the subjects to give an estimate for each symbol what percentage of the general population can understand the symbol meaning “fax”.
The subject’s judgment, given in the percentage form, was used as an estimate of his/her comprehension level of that symbol. A mixed-measure Analysis of Variance (ANOVA) test was used to test the difference between different graphical symbols (within subjects) and between different age group (between subjects), with Tukey’s test used for the post-hoc analysis. A significance threshold level of p < 0.05 was used for interpretation.
RESULTS AND DISCUSSION
The mean and standard deviation of overall responses grouped by each symbol and by each age group are shown in Table 2. Mixed-measure ANOVA with Tukey’s test (4 symbols X 4 age) showed that the estimated comprehensibility level of each graphical symbol is significantly different from each other; for age factor, the comprehension level of age 65+ group is significantly lower than age 31-50 group.
Symbol ID |
Graphical symbols |
Comprehension (Mean ± SD) |
Age group (Mean ± SD) |
|||
|---|---|---|---|---|---|---|
18-30 |
31-50 |
51-65 |
65+ |
|||
D |
|
23%±22% |
24%±21% |
23%±24% |
24±19% |
21%±25% |
A |
|
42%±26% |
40%±18% |
44%±27% |
42%±28% |
41%±26% |
B |
|
53%±27% |
56%±28% |
67%±22% |
45%±27% |
42%±25% |
C |
|
63%±27% |
65%±28% |
71%±23% |
58%±28% |
57±28% |
The results confirm our hypothesis that aging population has a lower comprehension level with graphical symbols. International standard symbols, tested by the procedures specified by ISO 9186 standard [7], collect data from three age groups: 18-30, 31-50 and 50+. A graphical symbol may meet the acceptance level specified by the ISO standard; however, it can still be difficult for aging population. Other studies also indicate that older people are more sensitive about the usability design issues [9]. Both suggest that to ensure the graphical symbol’s generic comprehensibility/usability, the test protocol should explicitly include a group of subjects who are 65 years or older.
A large-scale study including various symbols representing different meanings should be conducted in different culture to generalize the conclusion here. Future studies will also help to identify the influence of other demographics factors (e.g. culture, education level, occupation) besides age on the subjects’ comprehension on graphical symbols.
REFERENCES
- Wolff JS, Wogalter MS (1998). Comprehension of pictorial symbols: Effects of context and test method. Human Factors, 40(2):173-186.
- Brigham F (2001). Graphical symbols for consumer products in an international context. Information Design Journal, 10(2): 115-123.
- Piamonte DPT (2000). Using multiple performance parameters in testing small graphical symbols. Doctoral Dissertation, Lulea Tekniska University, Sweden.
- Brelsford JW, Wogalter MS, Scoggins JA (1997). Comprehension and retention of safety pictorials. Ergonomics, 40(5): 531-542.
- AoA (Administration on Aging) (2006). Administration on aging statistics on the aging population. See also: http://www.aoa.gov/prof/Statistics/statistics.asp
- ANSI (2002). ANSI Z535.3: Criteria for Safety Symbols.
- ISO (2006). ISO 9186-1: Graphical symbols: Procedures for comprehension testing.
- Foster JJ, Afzalnia MR (2005). International assessment of judged symbol comprehensibility. International Journal of Psychology, 40 (3), 169–175.
- Stephens EC, Carswell CM, Schumacher MM (2006). Evidence for an elders' advantage in the naive product usability judgments of older and younger adults. Human Factors, 48(3): 422-33.
ACKNOWLEDGMENTS
We thank Mr. Scott Kendall, Ms. Tina Reed and Mr. Daniel Jarvis for providing the graphical symbols and revising the survey used in this pilot study.
Correspondence Author Contact:
Xin Feng, Ph.D., Lexmark International, 740 West New Circle Road, Lexington, KY 40509, Phone: (859)-232-7832 Email: xinfeng@lexmark.com