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An evaluation of tactile symbols in public environment for the visually impaired
Applied Ergonomics 75 (2019) 193–200
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An evaluation of tactile symbols in public environment for the visually impaired
T
Cheng-Lung Lee Department of Industrial Engineering and Management, Chaoyang University of Technology, No. 168, Jifeng E. Rd, Wufeng District, Taichung, 41349, Taiwan, ROC
ARTICLE INFO
ABSTRACT
Keywords: Tactile symbol Visually impaired Confusion matrix
This study evaluated the identification performance of a set of tactile symbols used in public environments for the visually impaired. A questionnaire survey was carried out to investigate the public environment needs from 60 visually impaired associations. A two-stage experiment with a matching test was then conducted to explore the identification efficiency of graphic tactile public information symbols. Eighty-one students were recruited as participants from a school for the visually impaired. The survey results show that fourteen public buildings were frequently visited and ten architectural elements were mostly needed by the visually impaired. The experimental results showed the correct response of graphic symbols tested in both two-stage experiments could meet the identification criterion of 90% and even better except for the escalator/elevator with 87.0% in the second stage. Relevant confusion among the graphic symbols tested was found. Some suggestions were made in the study.
1. Introduction Tactile maps with raised-line pictures can be applied to convey spatial information to people with visual impairment and are frequently used to construct a cognitive map of a new environment (Brock et al., 2013; Gual et al., 2015; McCallum et al., 2005). The visually impaired can explore and learn about an unknown area before actually travelling and during the route through a tactile map (Gual et al., 2015). Three types of morphological elements used in tactile map design are point, linear and areal elements (Barth, 1982; Edman, 1992; Gual et al., 2015; Lederman and Kinch, 1979; Nolan and Morris, 1971). Point symbols are used to identify locations, linear symbols to identify boundaries or to connect points, and areal symbols are used to differentiate areas (Nolan and Morris, 1971). Symbol discrimination and identification are needed at the beginning of map reading (Perkins, 2002 cited in Lawrence and Lobben, 2011). Confusion regarding the tactile symbols may result in recognition error and low efficiency. The usage of Braille in tactile maps is critical (Brock et al., 2013). However, Braille text requires a lot of space and does not adapt to changes in orientation, inter-cell spacing and font properties (Tatham, 1991). Symbol design for tactile maps might help poor Braille readers to understand more easily. Jacobson (1996) argued that the use of separate legends in Braille might potentially introduce interpretation problems as referencing is disrupted during map reading. Symbol representation could be better than Braille for most people with visual impairment, implying that tactile map symbols could play an important
role. Tactile map symbols have been evaluated in many studies. Nolan and Morris (1971) summarized their five previous studies concerning the quality improvement of tactual symbols for the blind. They concluded that tactual perception, symbol legibility, map design and map user training played critical roles in tactual map use for the blind. In addition, several past symbol legibility literature were reviewed in their report. Symbol characteristics for legibility performance for the visually impaired were studied in the literature such as symbol size in Leung and Li (2002); symbol elevation (relief) in Barth (1982), and Jehoel et al. (2009); symbol texture in Bauer (1952), Heath (1958), Lederman and Kinch (1979), and Stellwagen and Culbert (1963); symbol meaningfulness in Lambert and Lederman (1989). Different production methods for representing tactile symbols (e.g., thermoforming, swell paper, embroidery, and 3D printing) could affect symbol readability (Gual et al., 2015; McCallum et al., 2005; Ramsamy-Iranah et al., 2016). Some studies recently developed multimodal interactive maps (Baker et al., 2016; Brock et al., 2013; Ducasse et al., 2018; Papadopoulos et al., 2017) through the use of technological devices such as audio-tactile maps. However, 3D printed tactile maps are rigid and not portable (Gual et al., 2015) and most interactive map prototypes are immobile for assisting with the preparation of itineraries at home before travelling (Brock et al., 2013). The choice and tactual representation of cartographic features may constitute the main challenge in designing a tactile map (Edman, 1992 cited in Schneider and Strothotte, 2000). Confusion for the map reader
E-mail address: [email protected]. https://doi.org/10.1016/j.apergo.2018.10.003 Received 6 August 2017; Received in revised form 12 September 2018; Accepted 13 October 2018 0003-6870/ © 2018 Elsevier Ltd. All rights reserved.
Applied Ergonomics 75 (2019) 193–200
C.-L. Lee
could result from the frequent arbitrary assignment of feature symbols, making it difficult to remember the meaning, requiring additional time spent referring to a legend (Lambert and Lederman, 1989). Most point symbols used to represent particular locations in tactile maps in the literature were chosen or drawn with geometric shapes such as circles, triangles, squares, pentagon, or combined figures (Brock et al., 2013; Lambert and Lederman, 1989; Ng and Chan, 2014; Nolan and Morris, 1971; Rowell and Ungar, 2003). Schiff (1966) explored the legibility of embossed upper-case English alphabet letters for use as tactile point symbols and found that most letter forms had high potential for symbolic tactual use. Little research has attempted to distinguish symbols based on meaningfulness. Symbols, including tactile ones, have not always been ascribed meanings that are obvious. Other than the few symbols that have iconic status, the nature of symbol representation is largely arbitrary (Rowell and Ungar, 2003). To read a tactile map effectively, a user must be able to discriminate and organize the symbols into a meaningful spatial data representation (Lawrence and Lobben, 2011). That is, in addition to being legible, tactile symbols should also be meaningful (Lambert and Lederman, 1989). A study was conducted to evaluate the legibility and meaningfulness of a series of point and linear symbols for potential use on tactual maps representing a building interior by Lambert and Lederman (1989). Their study results indicated that a symbol is easier to remember if it is meaningful to the participant. The miniature telephone receiver as the symbol for telephone yielded high accuracy scores, gained the lowest reaction times, scored high in meaningfulness, and was most preferred. Several participants recognized it correctly without being told. They addressed that both the pictographic features and the conceptual ideas were valuable in conveying meaning from participants’ test performance and subjective comments. This implies that the meaningfulness of tactile symbols with miniature shape might be one important factor in choosing symbols. Graphic symbols presented in public environments or on visual maps are used to indicate the public facilities or the direction of facilities and are generally provided to sighted people. These graphic symbols might be considered visually meaningful and some of them are miniature symbols for designated referents represented. However, such visual graphic symbols are not designed originally for the visually impaired. An attempt of this study was to examine whether the graphic symbols found on visual maps or in public environments would be legible and easily identified by the visually impaired. The study hypothesized that different graphic symbols used in public facilities would alter identification performance and the relevant confusion among graphic symbols would exist for the visually impaired. In addition a questionnaire survey was performed to determine the needs of the visually impaired in public environments in the study.
part asked for architectural element information that they needed first to know about large public buildings before visiting. Respondents were asked to select the first six architectural elements for each public facility. Scores were assigned with 6 points to 1 point from the first to the sixth element selected, respectively. Several discussions were held with two teachers, who were blind and teaching in the school, to modify the questionnaire before it was mailed. The response rate was 76.7% of delivered surveys and all were valid questionnaires. 2.2. Tactile symbol test 2.2.1. Experiment 1 A two-stage experiment was conducted using a tactile symbol matching test in this study. Experiment one was concerned with identifying the best symbol for each of the 10 selected referents which were obtained from the questionnaire results. This was done by collecting 5 potential symbols for each referent. These visual symbols were searched in real environments and domestic publications in Taiwan, e.g., the public symbols reference guideline of National Development Council (NDC, 2015). Additionally, some symbol examples were reviewed from the literature such as AIGA (2017), ISO 7001 (2007); Lambert and Lederman (1989), and Zwaga and Boersema (1983). For each referent, the participant was given a choice test board with the 5 symbols on. They were then shown each of the five symbols in turn on each a target board and the time they took to match the target symbol with the choice test symbols was measured. The order of choice test boards and target symbols presented to participants in the experiment was randomized. Choice test boards and target boards were made with thermoform paper which raised figures (i.e., symbols) appeared on it after printout from a heat-sensitive dimensional image copier and were then glued onto acrylic sheets. This swell paper method is a common way of producing tactile symbols and maps for visually impaired people (McCallum et al., 2005; Ramsamy-Iranah et al., 2016). The graphic symbol dimensions were 20 × 20 mm with elevation about 1 mm. All symbols were black figures on a white background. Fig. 1 shows choice test boards and target boards for the experiment. Eighty-one junior and senior high-school students were recruited from a school for the visually impaired in Central Taiwan. The experimental time data of two participants were missing and thus were eliminated from the study. A total of 79 valid participants included 22 junior high school students (aged 13–15) and 57 senior high school students (aged 16–18); 50 males and 29 females. Table 1 shows the participant characteristics. Participants were recruited after their class for the test. The testing sites were the participants’ classrooms. Each participant was tested individually. The participant was instructed to sit down in a chair and his/her personal data (shown in Table 1) were recorded by researchers before the experiment. A clear explanation of the experimental objectives and procedures was given to ensure no difficulties were experienced with the experiment by the participants. A brief training period was provided for the participant to ensure familiarity with the experiment before actual data were collected. An oral consent was obtained from each participant. Participants were given the opportunity to ask questions about the study with the option to withdraw at any time during the experiment. The response time and the symbols indicated by the participant on the choice test board were recorded during the experiment. No time limit was imposed for the matching test. There was no knowledge of the results provided to the participants during the experiment. Between the tests, a break of 10 s was taken for a short rest. Participants with low vision were blindfolded during the test. Fig. 2 shows the experiment for the first and second stages. Response time (RT) was defined as the time elapsed to complete a matching test when the participant thought and indicated a certain symbol on the choice board which was the same as the target symbol
2. Method 2.1. Survey of public facilities A questionnaire survey was conducted to obtain the daily life needs of the visually impaired in the public environment. Sixty visually impaired associations in Taiwan were selected based on their representative and geographic locations. They were asked by telephone for help in answering a questionnaire that they would soon receive by postal mail. In the questionnaire, a note was made to ask respondents to stand in for the visually impaired person while answering the questions. A second phone call was made to those who had not yet responded approximately three weeks after the questionnaire was mailed. The first part of the questionnaire contained the association's name, respondent's name and his/her job title, and the association location. The second part asked for public buildings that the visually impaired usually visited when they went out. Fourteen public buildings were presented in the questionnaire and a space was open for respondents to write in other public facilities that they might usually visit. The third 194
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Fig. 1. Choice test board and target board. (a) 5 stair graphic symbols for experiment 1; (b) 10 graphic symbols for experiment 2.
(CR) was the ratio of total correct matches to the total number of matching tests.
Table 1 Participant characteristics for both experiments. Variable Gender male female Grade level senior high junior high Visual status blind low vision Blindness condition congenitala acquireda Braille use yes no IQb superior average Memory skillc Yes no
Experiment 1 (n = 79)
Experiment 2 (n = 77)
50 (63.3%) 29 (36.7%)
49 (63.6%) 28 (36.4%)
57 (72.2%) 22 (27.8%)
55 (71.4%) 22 (28.6%)
36 (45.6%) 43 (54.4%)
38 (49.4%) 39 (50.6%)
52 (65.8%) 27 (34.2%)
51 (66.2%) 26 (33.8%)
54 (68.4%) 25 (31.6%)
55 (71.4%) 22 (28.6%)
16 (20.2%) 63 (79.8%)
15 (19.5%) 62 (80.5%)
34 (43.0%) 45 (57.0%)
35 (45.5%) 42 (54.5%)
2.2.2. Experiment 2 The same participants as experiment 1 were recruited but 4 students requested a leave of absence and thus 77 participants were tested. They were 22 junior high school students and 55 senior high school students; 49 males and 28 females. Table 1 shows the participant characteristics. Once the best symbol for each referent had been determined, experiment two was concerned with determining if the participants could distinguish each symbol easily from the other nine by being given a choice test board with the 10 symbols on and each of the symbols one at a time on a target board. This gave a measure of the effectiveness of the whole symbol set. The experimental procedure were the same as experiment 1. The order of target symbols presented to participants was randomized. This study (including a survey and a tactile symbol matching test) was approved by the Institutional Review Board for Ergonomic Experiments at Chaoyang University of Technology. 2.2.3. Data analysis A criterion was applied to determine the best matching symbol for each referent. A symbol with both the largest CR and the shortest MCRT was considered as the best matching symbol. A normalization procedure was taken to obtain the best matching symbol when the symbol had the largest CR but the MCRT was not the shortest. The symbol with largest CR was used as base symbol and the other symbols with shorter MCRT than the base symbol were considered together to normalize their CR and MCRT values and then to compare maximum difference ranges. The best symbol was the base symbol when CR maximum difference range was larger than the MCRT maximum difference range, indicating CR was the dominant factor. On the other hand, the best symbol was the symbol with the shortest MCRT, representing the dominant factor, when the maximum difference MCRT range was larger than that of CR. A final check for the chosen best symbol had to meet the identification criterion of 90% (Morris and Nolan, 1961 cited in
a Congenital status is defined as having no visual ability by the age of 5 and acquired status includes both low vision and having become blind. b IQ indicates intelligence quotient. The IQ classification of the participants was provided by the school supervisor according to the participants' performance in the school. c Memory skill was observed and determined subjectively by the researchers when participants performed the experiment.
given at the beginning. Correct response time (CRT) was the time considered only when the symbols were correctly matched on both test boards. Mean correct response time (MCRT) was the ratio of total correct response time to the total correct matches. Correct response 195
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Fig. 2. Matching tests for (a) experiment 1 and (b) experiment 2.
Lederman and Kinch, 1979). Such ten graphic symbols obtained were used as the test samples for experiment 2. Confusion matrix analysis is a useful measure of inter-figure similarity. The matching test in the study formed a 5 × 5 confusion matrix for each referent in experiment 1 and a 10 × 10 confusion matrix in experiment 2. The main diagonal gives the total correct matches of each target symbol with its symbol on choice test board indicated by the participants. The mismatches or confusion between the target symbol and the other 4 symbols on test board are given in the off-diagonal. Relevant confusion was defined as all entries of 16 and 8 or higher in a cell for both experiments, respectively. The number of 16 calculated, for instance, was the total number of participants (79) divided by the total number of tested symbols (5) in experiment 1. The criterion of relevant confusion applied was adopted from Zwaga and Boersema (1983). The relevant confusion produced by these matrices was examined in this study. The participant identification performance was represented as the total correct matches, examined with the analysis of variance (ANOVA) using SPSS 10.0 for Windows to explore the statistical significance (α = 0.05) for the experimental parameters.
3. Results 3.1. Public facility survey Fig. 3 shows the visit frequencies for 14 public buildings from 46 questionnaires replied to by the visually impaired associations. Other public facilities written in the free space in the questionnaire were audio library (8.6%), airport (4.3%), restaurant (4.3%), taxi stop (4.3%), traditional market (4.3%). A total of 25 architectural elements needed first to know by the visually impaired was scored in the range of 6-932. Table 2 shows the scores and the ranking of 10 architectural elements needed mostly in large public environments. Parking lot is also shown in Table 2 even its score was lower and ranked at the 19th but it usually exists in public environments. Parking lot was scored low because visually impaired people, as non-drivers, were unlikely to think about parking spaces. 3.2. Symbol test Ten referents representing the public architectural elements and buildings, each having 5 selected graphic symbols, were used for
Fig. 3. Visit frequencies for public buildings for the visually impaired (n = 46). MRT indicates mass rapid transit. 196
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Table 2 Scores and ranking of architectural elements needed by the visually impaired for selected large public facilities in the questionnaire survey. Architectural element
Railway station
Hospital
Government unit
Department store
School
Park
Others
Total Score
Ranking
1.Service center 2.Gateway 3.Guidepath 4.Toilet 5.Escalator/Elevator 6.Stairs 7.Bus stop 8.Phone booth 9.Registration office 10.Ticket office 11.Parking lot
164 159 134 87 39 28 – 25 – 150 –
154 117 122 60 28 16 – 21 169 – 6
207 182 134 86 96 54 – 28 – – –
156 175 104 81 51 21 – 23 – – 23
127 156 133 84 24 43 82 38 – – 3
– – 150 142 – 54 127 38 – – 13
124 109 107 72 33 23 – 34 – – 12
932 898 884 612 271 239 209 207 169 150 57
1 2 3 4 5 6 7 8 9 10 19
- not available for the public facility in the questionnaire.
tested symbols in experiment 2. The CRs of graphic symbols tested all met the identification criterion of 90% and better except for escalator/ elevator with 87.0%. No relevant confusion was found among the graphic symbols in experiment 2. The identification performance statistical analysis results in terms of total correct matches with significant differences for the visually impaired participants are shown in Table 7. The identification performance varied significantly across the groups in IQ (F = 4.071, p = .047) or memory skills (F = 4.206, p = .044) in experiment 1 and in Braille use (F = 4.442, p = .038), IQ (F = 4.677, p = .034), or memory skill (F = 9.221, p = .003) in experiment 2. No significant difference was detected between the groups in gender, grade, visual status, or blindness condition in both two-stage experiments. In addition, no significant difference in Braille use was found in experiment 1.
Table 3 Ten referents (each having 5 point symbols selected) selected for experiment 1.
4. Discussion Public environments visited and needed mostly by the visually impaired were surveyed in this study. Some architectural elements obtained lower scores due to the primary service of the public environments, such as ticket office at railway station, categories list at department store, and arbor at the park. No questions about access difficulties were asked in the present study. Several public buildings and architectural elements surveyed, such as businesses and physicians’ office, restaurant, food store, parking lot, building entrance, restroom and stair, were reported to have access barriers in the study of Thapar et al. (2004). Effective wayfinding and safe navigation in public environment should be the most predominant issues for the visually impaired. Hence, constructing a spatial map before a visit is needed and public facility access should be enhanced for the visually impaired. A set of visual graphic symbols used in public environments was tested in the study. This is an attempt to observe if the visual graphic symbols could be identified by the visually impaired. The study results indicated that most of the best symbols for each referent obtained in experiment 1 and all the best symbols tested in experiment 2 showed high identification performance, implying that such visual symbols chosen could be effectively identified by people with visual impairment. There is no systematic convention about the graphic symbols on a tactile map in Taiwan but symbol choice usually depends on the manufacturer or the customer. A specific referent sometimes may have several different symbols to be applied. Providing the visually impaired with a suitable symbol system could increase the legibility and effectiveness of map reading. Symbol matching was the method applied to examine the legibility of the graphic symbols in this study. Indeed, the study results provided experimentally the correct response and relevant confusion data of visual graphic symbols selected from public environments with the method applied. Several studies indicated that symbol standardization is important and desirable for tactile map design (Nolan and Morris, 1971; Rowell and Ungar, 2005), but an
experiment 1 as shown in Table 3. Nine referents (male and female toilets considered separately) were determined from the questionnaire survey results as shown in Table 2. The guide path used for establishing walking direction and the registration office, ticket office and the other architectural elements with low scores (not shown in Table 2) appeared at specific buildings were excluded. A hospital was included because it was the most popular facility to visit as shown in Fig. 3. Table 4 shows the CR and MCRT results and confusion matrices for ten referents determined in experiment 1. Table 5 shows the ten best matching graphic symbols obtained using the criterion procedure described. The bus stop, gateway and female toilet (i.e., the referents 2, 4, and 6) were determined as the best matching symbols using the normalization criterion. Relevant confusions among graphic symbols existed in experiment 1. Of the ten tested referents, four produced relevant confusions as shown in Table 4. These included symbols 1 and 5 for the hospital (i.e., referent 1) produced symmetrical confusion, symbols 4 and 5 for the gateway (referent 4) produced a symmetrically weak confusion effect, symbols 3 and 4 produced symmetrical confusion and symbols 3 and 5 produced asymmetrical confusion for the phone booth (referent 9), symbols 1 and 3 produced a symmetrically weak confusion effect for the parking lot (referent 10). Table 6 shows the CR and MCRT results and confusion matrix of 197
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Table 4 CR and MCRT results and confusion matrices for ten referents in experiment 1. Referent
1.Hospital
2.Bus stop
3.Service center
4.Gateway
5.Male toilet
6.Female toilet
7.Escalator/Elevator
8.Stairs
9.Phone booth
10.Parking lot
a
Symbol
CR (%)
MCRT (sec)
Table 5 Ten best graphic symbols obtained in experiment 1.
Symbol indicateda 1
2
3 6 4 70
4
1 2 3 4 5
57.8 78.3 84.3 92.8 56.6
11.5 12.9 11.0 8.1 14.1
48 1 3 16
5 65 4 1 8
1 2 3 4 5
84.8 81.0 93.7 92.4 91.1
14.3 17.8 12.4 11.8 10.1
67 11 1 4 4
7 64 3 1 2
1 2 74
1 2 3 4 5
91.1 87.3 79.7 83.5 91.1
8.4 10.5 15.5 16.5 10.8
72 3 4 3 1
2 69 7 3 2
2 3 63 4 4
2 3 3 66
1 2 3 4 5
94.9 98.7 92.4 77.2 65.8
13.2 9.1 8.0 13.0 13.4
75
2
5 1 2
78 1 1 1
2 1 73 2 2
1 2 3 4 5
78.5 91.1 86.1 82.3 88.6
17.3 10.8 13.4 18.3 12.0
62 4 3 3 2
5 72 1 1 1
1 2 3 4 5
79.7 87.3 92.4 70.9 89.9
13.0 14.2 13.2 17.3 14.5
63 8 2 4 1
9 69 1 9 3
1 2 3 4 5
89.9 82.3 81.0 84.8 78.5
12.7 17.5 15.7 16.7 12.9
71 4 2
7 65 11 3 2
1 2 3 4 5
94.9 84.8 91.1 89.9 82.3
7.0 12.1 15.9 16.0 18.0
75 1
1 2 3 4 5
98.7 91.1 64.6 49.4 69.6
8.1 10.5 15.5 22.1 19.6
78 2
1 2 3 4 5
67.1 91.1 78.5 84.8 88.6
16.8 11.1 13.9 12.8 18.3
53 3 14 2 1
8
77 1 73 1
5 20 9 2 1 47
14 52
3 1 68 7 2
8
1 2 1 3 70
2
3
73 7
3 56 4
4
72 4 2
1 4 3 71 3
7 4 2 65
72 6 2
3 51 24 19
1 1 17 39 5
1 5 14 55
2 72 1 10 3
17
2 9
62 2
4 4 1 67 3
CR (%)
MCRT (sec)
Choice symbol 1a
1 2 3 4 5 6 7 8 9 10 a
94.8 96.1 93.5 92.2 94.8 94.8 87.0 98.7 94.8 96.1
9.9 12.6 10.6 10.8 12.7 11.0 20.1 8.1 12.3 12.0
73 1 2
2
3
74 2
1 72 2 1
1 1
2
2 1
4
5
6
3 2 71 2
1
1 73 3
8
9
73 1
67 1
10
1
3
2
1
7
1 76 1
2 73
1 1 1 74
A blank in the table indicates no entry in the cell.
Table 7 Significant analysis of variance (ANOVA) results for both experiments. Experiment/Variable
3 71 2 1 9 62
3 67
Symbol
2 2
1 4 1 67 11
4 64
Table 6 CR and MCRT results and confusion matrix of graphic symbols in experiment 2.
1 1 2 3 72
61 22
6 65 4
Note: The best matching graphic symbol was determined using the largest CR and the shortest MCRT indicated by ∗ and with the normalization criterion indicated by ∗∗.
3 2 1 1 72
Experiment 1 IQ Memory skill Experiment 2 Braille use IQ Memory skill
Mean
SD
Effect
superior average yes no
44.81 41.08 43.59 40.51
4.34 7.05 5.24 7.46
superior > average
yes no superior average yes no
9.58 9.05 9.93 9.31 9.8 9.12
0.88 1.29 0.26 1.11 0.63 1.19
yes > no
yes > no
superior > average yes > no
Significance p < .05.
shapes or some other simple forms were commonly used for point symbols to represent specific locations in many studies. Such geometric shapes with arbitrary assignment of symbols to feature might result in the increase of perceptual loads and confusion among symbols during map reading. Lee (2017) conducted a survey on current tactile map problems and concluded that the shape of tactile symbol itself is difficult to come up with the actual meaning of the symbol. The symbol's physical properties can help to suggest the feature represented when the symbol is meaningful. The selected graphic symbols are meaningful to sighted people and most of them are miniature in this study. It is evident miniature symbols or the symbols that are meaningful could obtain high correct response, which was consistent with the study of Lambert and Lederman (1989). Ojala et al. (2017) stated that a tactile map cannot be a translation of visual information into tactual form as the tactile sense cannot provide the same resolution as the eye. Such visual graphic symbols thus should be further optimised to reduce the visual symbol complexity for the visually impaired but the readability of such symbols for sighted people could still be kept. A test should be conducted to observe both the visual and tactile effects on symbol
3 1 70
A blank in the table indicates no entry in the cell.
inventory of the greater numbers of legible symbols must be accumulated first. The results of this study might contribute to the evaluation of tactile symbol legibility for the visually impaired. Some concerns should be taken into account for tactile graphic symbol improvement in further study. Some visual graphic symbols tested in the study were likely more complex than those tested in the literature. Symbol complexity might increase readability difficulty for the visually impaired in distinguishing individual figures. Geometric 198
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modification obtained by the sighted and the visually impaired, respectively. The graphic symbols for 10 referents showed high CRs and no relevant confusions among them were found, indicating that these symbols selected were mostly accepted by the visually impaired participants. However, the service center and gateway symbols appeared similar shapes and the male and female toilet symbols showed different styles. Further improvement could be achieved by experimenting with alternatives to one of these similar symbols to make them more visually distinct. Additionally, the male and female symbols are functionally similar. The toilet symbols could be further adapted to be similar in visual style but still distinct from each other tactilely. At referent 7 in Table 3, symbol 1 is the escalator and the other 4 symbols are the elevator (lift). In actual practice, people in Taiwan sometimes use either the terms “elevator” or “escalator” to represent a device that can lift or lower people or things to different floors or levels even though they are different in definition. Symbol 1 (escalator) was determined as the best matching symbol since the CR was the highest and the MCRT was the shortest. The reason might be the shape of symbol 1 which was different from the other symbols (elevator). This did not appear to be the case, however, for parking lot (referent 10) in Table 3. The first 4 symbols selected were the figure containing a character P and the fifth one had an automobile shape. The best matching symbol for this referent was symbol 2 with both the most accurate and fastest response rate. The performance of symbol 5 presented more accurate but the slowest response. This implies that figure shape might not be the only important influence factor for the visually impaired in determining the accuracy or speed of symbol identification performance. No significant differences in identification performance detected between the groups in gender, grade level, visual status, or blindness condition. But significant differences between the groups in IQ, memory skill or Braille use were shown in the study. Most of the study results were consistent with the results obtained in the literature. Leo et al. (2017) did not detect statistical differences in performance enhancements between the groups in visual status in the tactile symbol recognition test. Ramsamy-Iranah et al. (2016) conducted a study to compare the effectiveness of different processes for manufacturing tactile symbols. As part of this work, they found that the relationship between age and color symbol recognition time was weak (r2 = 0.13) and no significant differences were observed between the groups in visual status or gender in their study. Ng and Chan (2014) found that the gender factor had no significant influence on tactual discrimination of different geometrical shapes. Brock et al. (2013) obtained a high level of user satisfaction with interactive maps for the visually impaired regardless of the users’ age, previous visual experience or Braille experience. Barth (1982) showed no difference attributable to grade grouping for tactile symbols tested. Nolan and Morris (1963) stated that no gender and grade level differences were found in the ability of students to discriminate point symbols. Morris and Nolan (1961) tested the relative legibility of areal symbols and found the ability to discriminate was not related to gender, grade level, or age but appeared to have a slight positive relation to mental ability (IQ) (Lederman and Kinch, 1979). The limitations of this study were that the survey was answered by the visually impaired association, the participants in the experiment were young and their travel environment was restricted mostly to a school campus or several limited sites that they frequently visited. Future study must interview with visually impaired individuals to obtain more detail needs information and collect larger samples with a wide range of ages and visual impairment on tactile test for further statistical analysis.
was tested through a questionnaire survey and a symbol identification experiment in this study. Correct response and response time were used to examine the accuracy and speed of symbol identification. Different graphic symbols for each referent presented various identification performance and the relevant confusion among graphic symbols existed in some referents. The hypothesis of current study proposed could then be proven. Even high correct responses were showed, modification of such graphic symbols should be further made and tested to enhance tactile map readability based on the simple form of tactile symbols which are needed by the people with visual impairment. The graphic symbol results obtained could be provided to the visual map producers for map symbol use and to the visually impaired schools for graphic symbol teaching in the class. Acknowledgements The author wish to thank the National Taichung Special Education School for the Visually Impaired and the visually impaired associations for their support and the participants for their time and patience in completing the questionnaire survey and tactile symbol matching tests. The author would like to thank Yun-Yen Lu for the help for data collection and statistic analysis. This work was supported by the National Science Council, Taiwan, ROC (NSC91-2614-E-324-001). References American Institute of Graphic Arts (AIGA), 2017, Available from: https://www.aiga.org/ symbol-signs. Baker, C.M., Milne, L.R., Drapeau, R., Scofield, J., Bennett, C.L., Ladner, R.E., 2016. Tactile graphics with a voice. ACM Transactions on Accessible Computing (TACCESS) 8 (1), 3. Barth, J.L., 1982. The development and evaluation of a tactile graphics kit. J. Vis. Impair. Blind. (JVIB) 76 (7), 269–273. Bauer, H.J., 1952. Discrimination of tactual stimuli. J. Exp. Psychol. Gen. 44 (6), 455–459. Brock, A., Oriola, B., Truillet, P., Jouffrais, C., Picard, D., 2013. Map design for visually impaired people: past, present, and future research. Médiation et Information. 36, 117–129. Ducasse, J., Brock, A.M., Jouffrais, C., 2018. Accessible interactive maps for visually impaired users. In: Mobility of Visually Impaired People, vols. 537–584 Springer, Cham. Edman, P.K., 1992. Tactile Graphics. American Foundation for the Blind (AFB), New York. Gual, J., Puyuelo, M., Lloveras, J., 2015. The effect of volumetric (3D) tactile symbols within inclusive tactile maps. Appl. Ergon. 48, 1–10. Heath, W.R., 1958. Maps and Graphics for the Blind: Some Aspects of the Discriminability of Textural Surfaces for Use in Areal Differentiation. University of Washington Doctoral dissertation. ISO 7001, 2007. Graphical Symbols – Public Information Symbols. International Standards Organization, Geneva, Switzerland. Jacobson, R.D., 1996. Talking tactile maps and environmental audio beacons: an orientation and mobility development tool for visually impaired people. In: Proceedings of the ICA Commission on Maps and Graphics for Blind and Visually Impaired People, vol. 96. pp. 1–22. Jehoel, S., Sowden, P.T., Ungar, S., Sterr, A., 2009. Tactile elevation perception in blind and sighted participants and its implications for tactile map creation. Hum. Factors 51 (2), 208–223. Lambert, L.M., Lederman, S.J., 1989. An evaluation of the legibility and meaningfulness of potential map symbols. J. Vis. Impair. Blind. (JVIB) 83 (8), 397–403. Lawrence, M.M., Lobben, A.K., 2011. The design of tactile thematic symbols. J. Vis. Impair. Blind. (JVIB) 105 (10), 681–691. Lederman, S.J., Kinch, D.H., 1979. Texture in tactual maps and graphics for the visually handicapped. J. Vis. Impair. Blind. (JVIB) 73 (6), 217–227. Lee, M., 2017, July. A SmarTactile map designed for the visually impaired to improve spatial cognition. In: International Conference on Applied Human Factors and Ergonomics. Springer, Cham, pp. 27–38. Leo, F., Cocchi, E., Brayda, L., 2017. The effect of programmable tactile displays on spatial learning skills in children and adolescents of different visual disability. IEEE Trans. Neural Syst. Rehabil. Eng. 25 (7), 861–872. Leung, L.F., Li, Z., 2002. Experimental evaluation of the effectiveness of graphic symbols on tourist maps. Cartography 31 (1), 11–20. McCallum, D., Ahmed, K., Jehoel, S., Dinar, S., Sheldon, D., 2005. The design and manufacture of tactile maps using an inkjet process. J. Eng. Des. 16 (6), 525–544. Morris, J.E., Nolan, C.Y., 1961. Discriminability of tactual patterns. Int. J. Educ. Blind. 11, 50–54. National Development Council (NDC), Taiwan, 2015. Public Symbols Reference Guideline. Ng, A.W., Chan, A.H., 2014. Tactile symbol matching of different shape patterns:
5. Conclusions A set of visual graphic symbols selected for the visually impaired 199
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C.-L. Lee implications for shape coding of control devices. In: Proceedings of the International MultiConference of Engineers and Computer Scientists, vol. 2. Nolan, C.Y., Morris, J.E., 1963. Tactual Symbols for the Blind: Final Report. American Printing House for the Blind, Louisville, KY, USA. Nolan, C.Y., Morris, J.E., 1971. Improvement of Tactual Symbols for Blind Children: Final Report. American Printing House for the Blind, Louisville, KY, USA. Ojala, S., Lahtinen, R., Hirn, H., 2017. Tactile maps–Finnish O&M instructors' experiences on usability and accessibility. Finn. J. eHealth eWelfare 9 (4), 313–321. Papadopoulos, K., Koustriava, E., Koukourikos, P., 2017. Orientation and mobility aids for individuals with blindness: verbal description vs. audio-tactile map. Assist. Technol. 1–10. Perkins, C., 2002. Cartography: progress in tactual mapping. Prog. Hum. Geogr. 26 (4), 521–530. Ramsamy-Iranah, S., Maguire, M., Gardner, J., Rosunee, S., Kistamah, N., 2016. A comparison of three materials used for tactile symbols to communicate colour to children and young people with visual impairments. Br. J. Vis. Impair. 34 (1), 54–71. Rowell, J., Ungar, S., 2003. A taxonomy for tactile symbols: creating a useable database for tactile map designers. Cartogr. J. 40 (3), 273–276.
Rowell, J., Ungar, S., 2005. Feeling our way: tactile map user requirements-a survey. In: International Cartographic Conference, La Coruna. Schiff, W., 1966. Raised Line Drawing Research Project: Final Report. Recording for the Blind, New York. Schneider, J., Strothotte, T., 2000. Constructive exploration of spatial information by blind users. In: Proceedings of the Fourth International ACM Conference on Assistive Technologies. ACM, pp. 188–192. Stellwagen, W.T., Culbert, S.S., 1963. Comparison of blind and sighted subjects in the discrimination of texture. Percept. Mot. Skills 17 (1), 61–62. Tatham, A.F., 1991. The design of tactile maps: theoretical and practical considerations. In: Rybaczak, K., Blakemore, M. (Eds.), Proceedings of International Cartographic Association: Mapping the Nations. ICA, London, UK, pp. 157–166. Thapar, N., Warner, G., Drainoni, M.L., Williams, S.R., Ditchfield, H., Wierbicky, J., Nesathurai, S., 2004. A pilot study of functional access to public buildings and facilities for persons with impairments. Disabil. Rehabil. 26 (5), 280–289. Zwaga, H.J., Boersema, T., 1983. Evaluation of a set of graphic symbols. Appl. Ergon. 14 (1), 43–54.
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An evaluation of tactile symbols in public environment for the visually impaired
T
Cheng-Lung Lee Department of Industrial Engineering and Management, Chaoyang University of Technology, No. 168, Jifeng E. Rd, Wufeng District, Taichung, 41349, Taiwan, ROC
ARTICLE INFO
ABSTRACT
Keywords: Tactile symbol Visually impaired Confusion matrix
This study evaluated the identification performance of a set of tactile symbols used in public environments for the visually impaired. A questionnaire survey was carried out to investigate the public environment needs from 60 visually impaired associations. A two-stage experiment with a matching test was then conducted to explore the identification efficiency of graphic tactile public information symbols. Eighty-one students were recruited as participants from a school for the visually impaired. The survey results show that fourteen public buildings were frequently visited and ten architectural elements were mostly needed by the visually impaired. The experimental results showed the correct response of graphic symbols tested in both two-stage experiments could meet the identification criterion of 90% and even better except for the escalator/elevator with 87.0% in the second stage. Relevant confusion among the graphic symbols tested was found. Some suggestions were made in the study.
1. Introduction Tactile maps with raised-line pictures can be applied to convey spatial information to people with visual impairment and are frequently used to construct a cognitive map of a new environment (Brock et al., 2013; Gual et al., 2015; McCallum et al., 2005). The visually impaired can explore and learn about an unknown area before actually travelling and during the route through a tactile map (Gual et al., 2015). Three types of morphological elements used in tactile map design are point, linear and areal elements (Barth, 1982; Edman, 1992; Gual et al., 2015; Lederman and Kinch, 1979; Nolan and Morris, 1971). Point symbols are used to identify locations, linear symbols to identify boundaries or to connect points, and areal symbols are used to differentiate areas (Nolan and Morris, 1971). Symbol discrimination and identification are needed at the beginning of map reading (Perkins, 2002 cited in Lawrence and Lobben, 2011). Confusion regarding the tactile symbols may result in recognition error and low efficiency. The usage of Braille in tactile maps is critical (Brock et al., 2013). However, Braille text requires a lot of space and does not adapt to changes in orientation, inter-cell spacing and font properties (Tatham, 1991). Symbol design for tactile maps might help poor Braille readers to understand more easily. Jacobson (1996) argued that the use of separate legends in Braille might potentially introduce interpretation problems as referencing is disrupted during map reading. Symbol representation could be better than Braille for most people with visual impairment, implying that tactile map symbols could play an important
role. Tactile map symbols have been evaluated in many studies. Nolan and Morris (1971) summarized their five previous studies concerning the quality improvement of tactual symbols for the blind. They concluded that tactual perception, symbol legibility, map design and map user training played critical roles in tactual map use for the blind. In addition, several past symbol legibility literature were reviewed in their report. Symbol characteristics for legibility performance for the visually impaired were studied in the literature such as symbol size in Leung and Li (2002); symbol elevation (relief) in Barth (1982), and Jehoel et al. (2009); symbol texture in Bauer (1952), Heath (1958), Lederman and Kinch (1979), and Stellwagen and Culbert (1963); symbol meaningfulness in Lambert and Lederman (1989). Different production methods for representing tactile symbols (e.g., thermoforming, swell paper, embroidery, and 3D printing) could affect symbol readability (Gual et al., 2015; McCallum et al., 2005; Ramsamy-Iranah et al., 2016). Some studies recently developed multimodal interactive maps (Baker et al., 2016; Brock et al., 2013; Ducasse et al., 2018; Papadopoulos et al., 2017) through the use of technological devices such as audio-tactile maps. However, 3D printed tactile maps are rigid and not portable (Gual et al., 2015) and most interactive map prototypes are immobile for assisting with the preparation of itineraries at home before travelling (Brock et al., 2013). The choice and tactual representation of cartographic features may constitute the main challenge in designing a tactile map (Edman, 1992 cited in Schneider and Strothotte, 2000). Confusion for the map reader
E-mail address: [email protected]. https://doi.org/10.1016/j.apergo.2018.10.003 Received 6 August 2017; Received in revised form 12 September 2018; Accepted 13 October 2018 0003-6870/ © 2018 Elsevier Ltd. All rights reserved.
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could result from the frequent arbitrary assignment of feature symbols, making it difficult to remember the meaning, requiring additional time spent referring to a legend (Lambert and Lederman, 1989). Most point symbols used to represent particular locations in tactile maps in the literature were chosen or drawn with geometric shapes such as circles, triangles, squares, pentagon, or combined figures (Brock et al., 2013; Lambert and Lederman, 1989; Ng and Chan, 2014; Nolan and Morris, 1971; Rowell and Ungar, 2003). Schiff (1966) explored the legibility of embossed upper-case English alphabet letters for use as tactile point symbols and found that most letter forms had high potential for symbolic tactual use. Little research has attempted to distinguish symbols based on meaningfulness. Symbols, including tactile ones, have not always been ascribed meanings that are obvious. Other than the few symbols that have iconic status, the nature of symbol representation is largely arbitrary (Rowell and Ungar, 2003). To read a tactile map effectively, a user must be able to discriminate and organize the symbols into a meaningful spatial data representation (Lawrence and Lobben, 2011). That is, in addition to being legible, tactile symbols should also be meaningful (Lambert and Lederman, 1989). A study was conducted to evaluate the legibility and meaningfulness of a series of point and linear symbols for potential use on tactual maps representing a building interior by Lambert and Lederman (1989). Their study results indicated that a symbol is easier to remember if it is meaningful to the participant. The miniature telephone receiver as the symbol for telephone yielded high accuracy scores, gained the lowest reaction times, scored high in meaningfulness, and was most preferred. Several participants recognized it correctly without being told. They addressed that both the pictographic features and the conceptual ideas were valuable in conveying meaning from participants’ test performance and subjective comments. This implies that the meaningfulness of tactile symbols with miniature shape might be one important factor in choosing symbols. Graphic symbols presented in public environments or on visual maps are used to indicate the public facilities or the direction of facilities and are generally provided to sighted people. These graphic symbols might be considered visually meaningful and some of them are miniature symbols for designated referents represented. However, such visual graphic symbols are not designed originally for the visually impaired. An attempt of this study was to examine whether the graphic symbols found on visual maps or in public environments would be legible and easily identified by the visually impaired. The study hypothesized that different graphic symbols used in public facilities would alter identification performance and the relevant confusion among graphic symbols would exist for the visually impaired. In addition a questionnaire survey was performed to determine the needs of the visually impaired in public environments in the study.
part asked for architectural element information that they needed first to know about large public buildings before visiting. Respondents were asked to select the first six architectural elements for each public facility. Scores were assigned with 6 points to 1 point from the first to the sixth element selected, respectively. Several discussions were held with two teachers, who were blind and teaching in the school, to modify the questionnaire before it was mailed. The response rate was 76.7% of delivered surveys and all were valid questionnaires. 2.2. Tactile symbol test 2.2.1. Experiment 1 A two-stage experiment was conducted using a tactile symbol matching test in this study. Experiment one was concerned with identifying the best symbol for each of the 10 selected referents which were obtained from the questionnaire results. This was done by collecting 5 potential symbols for each referent. These visual symbols were searched in real environments and domestic publications in Taiwan, e.g., the public symbols reference guideline of National Development Council (NDC, 2015). Additionally, some symbol examples were reviewed from the literature such as AIGA (2017), ISO 7001 (2007); Lambert and Lederman (1989), and Zwaga and Boersema (1983). For each referent, the participant was given a choice test board with the 5 symbols on. They were then shown each of the five symbols in turn on each a target board and the time they took to match the target symbol with the choice test symbols was measured. The order of choice test boards and target symbols presented to participants in the experiment was randomized. Choice test boards and target boards were made with thermoform paper which raised figures (i.e., symbols) appeared on it after printout from a heat-sensitive dimensional image copier and were then glued onto acrylic sheets. This swell paper method is a common way of producing tactile symbols and maps for visually impaired people (McCallum et al., 2005; Ramsamy-Iranah et al., 2016). The graphic symbol dimensions were 20 × 20 mm with elevation about 1 mm. All symbols were black figures on a white background. Fig. 1 shows choice test boards and target boards for the experiment. Eighty-one junior and senior high-school students were recruited from a school for the visually impaired in Central Taiwan. The experimental time data of two participants were missing and thus were eliminated from the study. A total of 79 valid participants included 22 junior high school students (aged 13–15) and 57 senior high school students (aged 16–18); 50 males and 29 females. Table 1 shows the participant characteristics. Participants were recruited after their class for the test. The testing sites were the participants’ classrooms. Each participant was tested individually. The participant was instructed to sit down in a chair and his/her personal data (shown in Table 1) were recorded by researchers before the experiment. A clear explanation of the experimental objectives and procedures was given to ensure no difficulties were experienced with the experiment by the participants. A brief training period was provided for the participant to ensure familiarity with the experiment before actual data were collected. An oral consent was obtained from each participant. Participants were given the opportunity to ask questions about the study with the option to withdraw at any time during the experiment. The response time and the symbols indicated by the participant on the choice test board were recorded during the experiment. No time limit was imposed for the matching test. There was no knowledge of the results provided to the participants during the experiment. Between the tests, a break of 10 s was taken for a short rest. Participants with low vision were blindfolded during the test. Fig. 2 shows the experiment for the first and second stages. Response time (RT) was defined as the time elapsed to complete a matching test when the participant thought and indicated a certain symbol on the choice board which was the same as the target symbol
2. Method 2.1. Survey of public facilities A questionnaire survey was conducted to obtain the daily life needs of the visually impaired in the public environment. Sixty visually impaired associations in Taiwan were selected based on their representative and geographic locations. They were asked by telephone for help in answering a questionnaire that they would soon receive by postal mail. In the questionnaire, a note was made to ask respondents to stand in for the visually impaired person while answering the questions. A second phone call was made to those who had not yet responded approximately three weeks after the questionnaire was mailed. The first part of the questionnaire contained the association's name, respondent's name and his/her job title, and the association location. The second part asked for public buildings that the visually impaired usually visited when they went out. Fourteen public buildings were presented in the questionnaire and a space was open for respondents to write in other public facilities that they might usually visit. The third 194
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Fig. 1. Choice test board and target board. (a) 5 stair graphic symbols for experiment 1; (b) 10 graphic symbols for experiment 2.
(CR) was the ratio of total correct matches to the total number of matching tests.
Table 1 Participant characteristics for both experiments. Variable Gender male female Grade level senior high junior high Visual status blind low vision Blindness condition congenitala acquireda Braille use yes no IQb superior average Memory skillc Yes no
Experiment 1 (n = 79)
Experiment 2 (n = 77)
50 (63.3%) 29 (36.7%)
49 (63.6%) 28 (36.4%)
57 (72.2%) 22 (27.8%)
55 (71.4%) 22 (28.6%)
36 (45.6%) 43 (54.4%)
38 (49.4%) 39 (50.6%)
52 (65.8%) 27 (34.2%)
51 (66.2%) 26 (33.8%)
54 (68.4%) 25 (31.6%)
55 (71.4%) 22 (28.6%)
16 (20.2%) 63 (79.8%)
15 (19.5%) 62 (80.5%)
34 (43.0%) 45 (57.0%)
35 (45.5%) 42 (54.5%)
2.2.2. Experiment 2 The same participants as experiment 1 were recruited but 4 students requested a leave of absence and thus 77 participants were tested. They were 22 junior high school students and 55 senior high school students; 49 males and 28 females. Table 1 shows the participant characteristics. Once the best symbol for each referent had been determined, experiment two was concerned with determining if the participants could distinguish each symbol easily from the other nine by being given a choice test board with the 10 symbols on and each of the symbols one at a time on a target board. This gave a measure of the effectiveness of the whole symbol set. The experimental procedure were the same as experiment 1. The order of target symbols presented to participants was randomized. This study (including a survey and a tactile symbol matching test) was approved by the Institutional Review Board for Ergonomic Experiments at Chaoyang University of Technology. 2.2.3. Data analysis A criterion was applied to determine the best matching symbol for each referent. A symbol with both the largest CR and the shortest MCRT was considered as the best matching symbol. A normalization procedure was taken to obtain the best matching symbol when the symbol had the largest CR but the MCRT was not the shortest. The symbol with largest CR was used as base symbol and the other symbols with shorter MCRT than the base symbol were considered together to normalize their CR and MCRT values and then to compare maximum difference ranges. The best symbol was the base symbol when CR maximum difference range was larger than the MCRT maximum difference range, indicating CR was the dominant factor. On the other hand, the best symbol was the symbol with the shortest MCRT, representing the dominant factor, when the maximum difference MCRT range was larger than that of CR. A final check for the chosen best symbol had to meet the identification criterion of 90% (Morris and Nolan, 1961 cited in
a Congenital status is defined as having no visual ability by the age of 5 and acquired status includes both low vision and having become blind. b IQ indicates intelligence quotient. The IQ classification of the participants was provided by the school supervisor according to the participants' performance in the school. c Memory skill was observed and determined subjectively by the researchers when participants performed the experiment.
given at the beginning. Correct response time (CRT) was the time considered only when the symbols were correctly matched on both test boards. Mean correct response time (MCRT) was the ratio of total correct response time to the total correct matches. Correct response 195
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Fig. 2. Matching tests for (a) experiment 1 and (b) experiment 2.
Lederman and Kinch, 1979). Such ten graphic symbols obtained were used as the test samples for experiment 2. Confusion matrix analysis is a useful measure of inter-figure similarity. The matching test in the study formed a 5 × 5 confusion matrix for each referent in experiment 1 and a 10 × 10 confusion matrix in experiment 2. The main diagonal gives the total correct matches of each target symbol with its symbol on choice test board indicated by the participants. The mismatches or confusion between the target symbol and the other 4 symbols on test board are given in the off-diagonal. Relevant confusion was defined as all entries of 16 and 8 or higher in a cell for both experiments, respectively. The number of 16 calculated, for instance, was the total number of participants (79) divided by the total number of tested symbols (5) in experiment 1. The criterion of relevant confusion applied was adopted from Zwaga and Boersema (1983). The relevant confusion produced by these matrices was examined in this study. The participant identification performance was represented as the total correct matches, examined with the analysis of variance (ANOVA) using SPSS 10.0 for Windows to explore the statistical significance (α = 0.05) for the experimental parameters.
3. Results 3.1. Public facility survey Fig. 3 shows the visit frequencies for 14 public buildings from 46 questionnaires replied to by the visually impaired associations. Other public facilities written in the free space in the questionnaire were audio library (8.6%), airport (4.3%), restaurant (4.3%), taxi stop (4.3%), traditional market (4.3%). A total of 25 architectural elements needed first to know by the visually impaired was scored in the range of 6-932. Table 2 shows the scores and the ranking of 10 architectural elements needed mostly in large public environments. Parking lot is also shown in Table 2 even its score was lower and ranked at the 19th but it usually exists in public environments. Parking lot was scored low because visually impaired people, as non-drivers, were unlikely to think about parking spaces. 3.2. Symbol test Ten referents representing the public architectural elements and buildings, each having 5 selected graphic symbols, were used for
Fig. 3. Visit frequencies for public buildings for the visually impaired (n = 46). MRT indicates mass rapid transit. 196
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Table 2 Scores and ranking of architectural elements needed by the visually impaired for selected large public facilities in the questionnaire survey. Architectural element
Railway station
Hospital
Government unit
Department store
School
Park
Others
Total Score
Ranking
1.Service center 2.Gateway 3.Guidepath 4.Toilet 5.Escalator/Elevator 6.Stairs 7.Bus stop 8.Phone booth 9.Registration office 10.Ticket office 11.Parking lot
164 159 134 87 39 28 – 25 – 150 –
154 117 122 60 28 16 – 21 169 – 6
207 182 134 86 96 54 – 28 – – –
156 175 104 81 51 21 – 23 – – 23
127 156 133 84 24 43 82 38 – – 3
– – 150 142 – 54 127 38 – – 13
124 109 107 72 33 23 – 34 – – 12
932 898 884 612 271 239 209 207 169 150 57
1 2 3 4 5 6 7 8 9 10 19
- not available for the public facility in the questionnaire.
tested symbols in experiment 2. The CRs of graphic symbols tested all met the identification criterion of 90% and better except for escalator/ elevator with 87.0%. No relevant confusion was found among the graphic symbols in experiment 2. The identification performance statistical analysis results in terms of total correct matches with significant differences for the visually impaired participants are shown in Table 7. The identification performance varied significantly across the groups in IQ (F = 4.071, p = .047) or memory skills (F = 4.206, p = .044) in experiment 1 and in Braille use (F = 4.442, p = .038), IQ (F = 4.677, p = .034), or memory skill (F = 9.221, p = .003) in experiment 2. No significant difference was detected between the groups in gender, grade, visual status, or blindness condition in both two-stage experiments. In addition, no significant difference in Braille use was found in experiment 1.
Table 3 Ten referents (each having 5 point symbols selected) selected for experiment 1.
4. Discussion Public environments visited and needed mostly by the visually impaired were surveyed in this study. Some architectural elements obtained lower scores due to the primary service of the public environments, such as ticket office at railway station, categories list at department store, and arbor at the park. No questions about access difficulties were asked in the present study. Several public buildings and architectural elements surveyed, such as businesses and physicians’ office, restaurant, food store, parking lot, building entrance, restroom and stair, were reported to have access barriers in the study of Thapar et al. (2004). Effective wayfinding and safe navigation in public environment should be the most predominant issues for the visually impaired. Hence, constructing a spatial map before a visit is needed and public facility access should be enhanced for the visually impaired. A set of visual graphic symbols used in public environments was tested in the study. This is an attempt to observe if the visual graphic symbols could be identified by the visually impaired. The study results indicated that most of the best symbols for each referent obtained in experiment 1 and all the best symbols tested in experiment 2 showed high identification performance, implying that such visual symbols chosen could be effectively identified by people with visual impairment. There is no systematic convention about the graphic symbols on a tactile map in Taiwan but symbol choice usually depends on the manufacturer or the customer. A specific referent sometimes may have several different symbols to be applied. Providing the visually impaired with a suitable symbol system could increase the legibility and effectiveness of map reading. Symbol matching was the method applied to examine the legibility of the graphic symbols in this study. Indeed, the study results provided experimentally the correct response and relevant confusion data of visual graphic symbols selected from public environments with the method applied. Several studies indicated that symbol standardization is important and desirable for tactile map design (Nolan and Morris, 1971; Rowell and Ungar, 2005), but an
experiment 1 as shown in Table 3. Nine referents (male and female toilets considered separately) were determined from the questionnaire survey results as shown in Table 2. The guide path used for establishing walking direction and the registration office, ticket office and the other architectural elements with low scores (not shown in Table 2) appeared at specific buildings were excluded. A hospital was included because it was the most popular facility to visit as shown in Fig. 3. Table 4 shows the CR and MCRT results and confusion matrices for ten referents determined in experiment 1. Table 5 shows the ten best matching graphic symbols obtained using the criterion procedure described. The bus stop, gateway and female toilet (i.e., the referents 2, 4, and 6) were determined as the best matching symbols using the normalization criterion. Relevant confusions among graphic symbols existed in experiment 1. Of the ten tested referents, four produced relevant confusions as shown in Table 4. These included symbols 1 and 5 for the hospital (i.e., referent 1) produced symmetrical confusion, symbols 4 and 5 for the gateway (referent 4) produced a symmetrically weak confusion effect, symbols 3 and 4 produced symmetrical confusion and symbols 3 and 5 produced asymmetrical confusion for the phone booth (referent 9), symbols 1 and 3 produced a symmetrically weak confusion effect for the parking lot (referent 10). Table 6 shows the CR and MCRT results and confusion matrix of 197
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Table 4 CR and MCRT results and confusion matrices for ten referents in experiment 1. Referent
1.Hospital
2.Bus stop
3.Service center
4.Gateway
5.Male toilet
6.Female toilet
7.Escalator/Elevator
8.Stairs
9.Phone booth
10.Parking lot
a
Symbol
CR (%)
MCRT (sec)
Table 5 Ten best graphic symbols obtained in experiment 1.
Symbol indicateda 1
2
3 6 4 70
4
1 2 3 4 5
57.8 78.3 84.3 92.8 56.6
11.5 12.9 11.0 8.1 14.1
48 1 3 16
5 65 4 1 8
1 2 3 4 5
84.8 81.0 93.7 92.4 91.1
14.3 17.8 12.4 11.8 10.1
67 11 1 4 4
7 64 3 1 2
1 2 74
1 2 3 4 5
91.1 87.3 79.7 83.5 91.1
8.4 10.5 15.5 16.5 10.8
72 3 4 3 1
2 69 7 3 2
2 3 63 4 4
2 3 3 66
1 2 3 4 5
94.9 98.7 92.4 77.2 65.8
13.2 9.1 8.0 13.0 13.4
75
2
5 1 2
78 1 1 1
2 1 73 2 2
1 2 3 4 5
78.5 91.1 86.1 82.3 88.6
17.3 10.8 13.4 18.3 12.0
62 4 3 3 2
5 72 1 1 1
1 2 3 4 5
79.7 87.3 92.4 70.9 89.9
13.0 14.2 13.2 17.3 14.5
63 8 2 4 1
9 69 1 9 3
1 2 3 4 5
89.9 82.3 81.0 84.8 78.5
12.7 17.5 15.7 16.7 12.9
71 4 2
7 65 11 3 2
1 2 3 4 5
94.9 84.8 91.1 89.9 82.3
7.0 12.1 15.9 16.0 18.0
75 1
1 2 3 4 5
98.7 91.1 64.6 49.4 69.6
8.1 10.5 15.5 22.1 19.6
78 2
1 2 3 4 5
67.1 91.1 78.5 84.8 88.6
16.8 11.1 13.9 12.8 18.3
53 3 14 2 1
8
77 1 73 1
5 20 9 2 1 47
14 52
3 1 68 7 2
8
1 2 1 3 70
2
3
73 7
3 56 4
4
72 4 2
1 4 3 71 3
7 4 2 65
72 6 2
3 51 24 19
1 1 17 39 5
1 5 14 55
2 72 1 10 3
17
2 9
62 2
4 4 1 67 3
CR (%)
MCRT (sec)
Choice symbol 1a
1 2 3 4 5 6 7 8 9 10 a
94.8 96.1 93.5 92.2 94.8 94.8 87.0 98.7 94.8 96.1
9.9 12.6 10.6 10.8 12.7 11.0 20.1 8.1 12.3 12.0
73 1 2
2
3
74 2
1 72 2 1
1 1
2
2 1
4
5
6
3 2 71 2
1
1 73 3
8
9
73 1
67 1
10
1
3
2
1
7
1 76 1
2 73
1 1 1 74
A blank in the table indicates no entry in the cell.
Table 7 Significant analysis of variance (ANOVA) results for both experiments. Experiment/Variable
3 71 2 1 9 62
3 67
Symbol
2 2
1 4 1 67 11
4 64
Table 6 CR and MCRT results and confusion matrix of graphic symbols in experiment 2.
1 1 2 3 72
61 22
6 65 4
Note: The best matching graphic symbol was determined using the largest CR and the shortest MCRT indicated by ∗ and with the normalization criterion indicated by ∗∗.
3 2 1 1 72
Experiment 1 IQ Memory skill Experiment 2 Braille use IQ Memory skill
Mean
SD
Effect
superior average yes no
44.81 41.08 43.59 40.51
4.34 7.05 5.24 7.46
superior > average
yes no superior average yes no
9.58 9.05 9.93 9.31 9.8 9.12
0.88 1.29 0.26 1.11 0.63 1.19
yes > no
yes > no
superior > average yes > no
Significance p < .05.
shapes or some other simple forms were commonly used for point symbols to represent specific locations in many studies. Such geometric shapes with arbitrary assignment of symbols to feature might result in the increase of perceptual loads and confusion among symbols during map reading. Lee (2017) conducted a survey on current tactile map problems and concluded that the shape of tactile symbol itself is difficult to come up with the actual meaning of the symbol. The symbol's physical properties can help to suggest the feature represented when the symbol is meaningful. The selected graphic symbols are meaningful to sighted people and most of them are miniature in this study. It is evident miniature symbols or the symbols that are meaningful could obtain high correct response, which was consistent with the study of Lambert and Lederman (1989). Ojala et al. (2017) stated that a tactile map cannot be a translation of visual information into tactual form as the tactile sense cannot provide the same resolution as the eye. Such visual graphic symbols thus should be further optimised to reduce the visual symbol complexity for the visually impaired but the readability of such symbols for sighted people could still be kept. A test should be conducted to observe both the visual and tactile effects on symbol
3 1 70
A blank in the table indicates no entry in the cell.
inventory of the greater numbers of legible symbols must be accumulated first. The results of this study might contribute to the evaluation of tactile symbol legibility for the visually impaired. Some concerns should be taken into account for tactile graphic symbol improvement in further study. Some visual graphic symbols tested in the study were likely more complex than those tested in the literature. Symbol complexity might increase readability difficulty for the visually impaired in distinguishing individual figures. Geometric 198
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C.-L. Lee
modification obtained by the sighted and the visually impaired, respectively. The graphic symbols for 10 referents showed high CRs and no relevant confusions among them were found, indicating that these symbols selected were mostly accepted by the visually impaired participants. However, the service center and gateway symbols appeared similar shapes and the male and female toilet symbols showed different styles. Further improvement could be achieved by experimenting with alternatives to one of these similar symbols to make them more visually distinct. Additionally, the male and female symbols are functionally similar. The toilet symbols could be further adapted to be similar in visual style but still distinct from each other tactilely. At referent 7 in Table 3, symbol 1 is the escalator and the other 4 symbols are the elevator (lift). In actual practice, people in Taiwan sometimes use either the terms “elevator” or “escalator” to represent a device that can lift or lower people or things to different floors or levels even though they are different in definition. Symbol 1 (escalator) was determined as the best matching symbol since the CR was the highest and the MCRT was the shortest. The reason might be the shape of symbol 1 which was different from the other symbols (elevator). This did not appear to be the case, however, for parking lot (referent 10) in Table 3. The first 4 symbols selected were the figure containing a character P and the fifth one had an automobile shape. The best matching symbol for this referent was symbol 2 with both the most accurate and fastest response rate. The performance of symbol 5 presented more accurate but the slowest response. This implies that figure shape might not be the only important influence factor for the visually impaired in determining the accuracy or speed of symbol identification performance. No significant differences in identification performance detected between the groups in gender, grade level, visual status, or blindness condition. But significant differences between the groups in IQ, memory skill or Braille use were shown in the study. Most of the study results were consistent with the results obtained in the literature. Leo et al. (2017) did not detect statistical differences in performance enhancements between the groups in visual status in the tactile symbol recognition test. Ramsamy-Iranah et al. (2016) conducted a study to compare the effectiveness of different processes for manufacturing tactile symbols. As part of this work, they found that the relationship between age and color symbol recognition time was weak (r2 = 0.13) and no significant differences were observed between the groups in visual status or gender in their study. Ng and Chan (2014) found that the gender factor had no significant influence on tactual discrimination of different geometrical shapes. Brock et al. (2013) obtained a high level of user satisfaction with interactive maps for the visually impaired regardless of the users’ age, previous visual experience or Braille experience. Barth (1982) showed no difference attributable to grade grouping for tactile symbols tested. Nolan and Morris (1963) stated that no gender and grade level differences were found in the ability of students to discriminate point symbols. Morris and Nolan (1961) tested the relative legibility of areal symbols and found the ability to discriminate was not related to gender, grade level, or age but appeared to have a slight positive relation to mental ability (IQ) (Lederman and Kinch, 1979). The limitations of this study were that the survey was answered by the visually impaired association, the participants in the experiment were young and their travel environment was restricted mostly to a school campus or several limited sites that they frequently visited. Future study must interview with visually impaired individuals to obtain more detail needs information and collect larger samples with a wide range of ages and visual impairment on tactile test for further statistical analysis.
was tested through a questionnaire survey and a symbol identification experiment in this study. Correct response and response time were used to examine the accuracy and speed of symbol identification. Different graphic symbols for each referent presented various identification performance and the relevant confusion among graphic symbols existed in some referents. The hypothesis of current study proposed could then be proven. Even high correct responses were showed, modification of such graphic symbols should be further made and tested to enhance tactile map readability based on the simple form of tactile symbols which are needed by the people with visual impairment. The graphic symbol results obtained could be provided to the visual map producers for map symbol use and to the visually impaired schools for graphic symbol teaching in the class. Acknowledgements The author wish to thank the National Taichung Special Education School for the Visually Impaired and the visually impaired associations for their support and the participants for their time and patience in completing the questionnaire survey and tactile symbol matching tests. The author would like to thank Yun-Yen Lu for the help for data collection and statistic analysis. This work was supported by the National Science Council, Taiwan, ROC (NSC91-2614-E-324-001). References American Institute of Graphic Arts (AIGA), 2017, Available from: https://www.aiga.org/ symbol-signs. Baker, C.M., Milne, L.R., Drapeau, R., Scofield, J., Bennett, C.L., Ladner, R.E., 2016. Tactile graphics with a voice. ACM Transactions on Accessible Computing (TACCESS) 8 (1), 3. Barth, J.L., 1982. The development and evaluation of a tactile graphics kit. J. Vis. Impair. Blind. (JVIB) 76 (7), 269–273. Bauer, H.J., 1952. Discrimination of tactual stimuli. J. Exp. Psychol. Gen. 44 (6), 455–459. Brock, A., Oriola, B., Truillet, P., Jouffrais, C., Picard, D., 2013. Map design for visually impaired people: past, present, and future research. Médiation et Information. 36, 117–129. Ducasse, J., Brock, A.M., Jouffrais, C., 2018. Accessible interactive maps for visually impaired users. In: Mobility of Visually Impaired People, vols. 537–584 Springer, Cham. Edman, P.K., 1992. Tactile Graphics. American Foundation for the Blind (AFB), New York. Gual, J., Puyuelo, M., Lloveras, J., 2015. The effect of volumetric (3D) tactile symbols within inclusive tactile maps. Appl. Ergon. 48, 1–10. Heath, W.R., 1958. Maps and Graphics for the Blind: Some Aspects of the Discriminability of Textural Surfaces for Use in Areal Differentiation. University of Washington Doctoral dissertation. ISO 7001, 2007. Graphical Symbols – Public Information Symbols. International Standards Organization, Geneva, Switzerland. Jacobson, R.D., 1996. Talking tactile maps and environmental audio beacons: an orientation and mobility development tool for visually impaired people. In: Proceedings of the ICA Commission on Maps and Graphics for Blind and Visually Impaired People, vol. 96. pp. 1–22. Jehoel, S., Sowden, P.T., Ungar, S., Sterr, A., 2009. Tactile elevation perception in blind and sighted participants and its implications for tactile map creation. Hum. Factors 51 (2), 208–223. Lambert, L.M., Lederman, S.J., 1989. An evaluation of the legibility and meaningfulness of potential map symbols. J. Vis. Impair. Blind. (JVIB) 83 (8), 397–403. Lawrence, M.M., Lobben, A.K., 2011. The design of tactile thematic symbols. J. Vis. Impair. Blind. (JVIB) 105 (10), 681–691. Lederman, S.J., Kinch, D.H., 1979. Texture in tactual maps and graphics for the visually handicapped. J. Vis. Impair. Blind. (JVIB) 73 (6), 217–227. Lee, M., 2017, July. A SmarTactile map designed for the visually impaired to improve spatial cognition. In: International Conference on Applied Human Factors and Ergonomics. Springer, Cham, pp. 27–38. Leo, F., Cocchi, E., Brayda, L., 2017. The effect of programmable tactile displays on spatial learning skills in children and adolescents of different visual disability. IEEE Trans. Neural Syst. Rehabil. Eng. 25 (7), 861–872. Leung, L.F., Li, Z., 2002. Experimental evaluation of the effectiveness of graphic symbols on tourist maps. Cartography 31 (1), 11–20. McCallum, D., Ahmed, K., Jehoel, S., Dinar, S., Sheldon, D., 2005. The design and manufacture of tactile maps using an inkjet process. J. Eng. Des. 16 (6), 525–544. Morris, J.E., Nolan, C.Y., 1961. Discriminability of tactual patterns. Int. J. Educ. Blind. 11, 50–54. National Development Council (NDC), Taiwan, 2015. Public Symbols Reference Guideline. Ng, A.W., Chan, A.H., 2014. Tactile symbol matching of different shape patterns:
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