1、1 ECHNICAL - REPORT ETR 261-4 October 1996 Source: ETSI TC-HF Reference: DTWHF-01028-4 ICs: 33.020 Key words: Keypad, MMI, supplementary service Human Factors (HF); Assessment and definition of a harmonized minimum man-machine interface (MMI) for accessing and controlling public network based supple
2、mentary services; Part 4: Experimental comparison of the effect of categorized and non-categorized formats within user instructions European Telecommunications Standards Institute ETSI Secretariat Postal address: F-O6921 Sophia Antipolis CEDEX - FRANCE office address: 650 Route des Lucioles - Sophia
3、 Antipolis - Valbonne - FRANCE X.40: c=fr, a=atlas, p=etsi, ssecretariat - Internet: secretariat etsi.fr Tel.: +33 4 92 94 42 O0 - Fax: +33 4 93 65 47 16 Copyright Notification: No pari may be reproduced except as authorized by written permission. The copyright and the foregoing restriction extend t
4、o reproduction in all media. Q European Telecommunications Standards Institute 1996. All rights reserved. - - ETSI ETR*263-4 96 = 3400855 0343742 Oh3 Page 2 flR 261-4: October 1996 Whilst every care has been taken in the preparation and publication of this document, errors in content, typographical
5、or otherwise, may occur. if you have comments concerning its accuracy, please write to “ETSI Editing and Committee Support Dept.“ at the address shown on the title page. ETSI ETR*ZbL-4 96 = 3400855 0141743 TTT Page 3 ETR 261-4: October 1996 Contents Foreword . 7 Introduction 7 1 Scope 9 2 References
6、 9 3 Definitions. symbols and abbreviations . 11 4.2.2 4 Theoretical Background 11 Usability of Existing Features and Functions . 11 4.1 4.1.1 Summary . 12 4.2 Mental models 13 4.2.1 Mental models of supplementary services 13 4.2.1.1 Mental representations of telephony 13 4.2.1.2 Mental representati
7、ons of supplementary services . 14 4.2.1.3 Remembering the commands . 15 4.2.1.4 Presentation: how to communicate the conceptual model to the user 17 4.2.2.1 The (designers) intended conceptual model, the (manuals) transmitted conceptual model and the (users) actual conceptual model 18 4.2.2.2 The i
8、nformation retrieval model . 19 4.3 Elderly users 19 4.3.1 Elderly peoples models of devices . 20 4.4 Hypothesis, expectations and research questions 20 4.4.1 Research questions . 20 4.4.2 Hypothesis . 21 Information presented by the system 17 5 Two different conceptual models 21 5.1 The categories
9、manual 21 5.1 . 1 A narrow two layer hierarchical model . 22 5.1.1 . 1 Six categories 22 5.1 . 1 . 2 Services within categories . 22 5.1 . 1.3 Syntax 22 5.1.2 Table of Services . 22 5.1.3 User Manual 23 The No Categories manual 23 5.2.1 A flat and broad model 24 5.2.2 Table of Services . 24 5.2.3 Us
10、er Manual 24 5.2 6 An enhanced minimal phone based interface for ISDN supplementary services . 25 6.1 Design 25 6.1.1 Visually displayed menus: parallel presentation of information is impossible . 26 6.1.2 Auditory Instructions 26 6.1.3 Recognition and aided recall vs . plain recall . 26 6.1.4 Use o
11、f shortcuts 27 6.1.5 The final prototype . 27 6.2 Simulation 28 6.3 Differences between the CAT and the NoCAT User Interface 29 7 Method 29 7.1 Experimental Task . 29 ETSI ETR*2bl1-4 76 3400855 Ol14L744 936 Page 4 ETR 261-4: October 1996 7.2 7.3 7.4 7.5 7.6 7.7 7.8 Experimental Design and Independen
12、t Variables . 30 7.2.1 Supplementary services and scenarios 30 7.2.2 Type of conceptual model - CAT vs . NoCAT 31 7.2.3 Age . 31 7.2.4 Subjects 31 Data registration 31 7.3.1 Performance measures 31 7.3.1.1 Video-registration 31 7.3.1.2 Observations . 32 7.3.1.3 Logging of subjects actions 32 7.3.1.4
13、 “Model test“ . 32 7.3.1.5 “Repeated model test“ 32 Personal background data 32 7.3.2.1 Structured interview 32 7.3.2.2 Standard progressive matrices . 32 7.3.3 Subjective measures 33 7.3.3.1 Subjective mental effort 33 7.3.3.2 Acceptance questionnaire . 33 Definition of dependent variables 33 7.4.1
14、 Duration of scenario 33 7.4.2 Duration of manual consultation(s) . 33 7.4.3 Errors 34 7.4.4 Level of “abstract intelligence 34 7.4.5 Model test scores 34 7.4.6 Treatment of missing data 34 Procedure 35 7.5.1 Time limit 35 Pilot study 36 Hypothesis . 36 Statistical Analyses . 37 7.3.2 8 9 Results 37
15、 8.1 Descriptive statistics with regard to the elderly . 37 8.2 Effects of different types of transmitted conceptual model and effects of practice . 39 8.2.1 Duration of manual consultations and duration of scenarios will decrease with time/scenario . 39 8.2.2 Subjective mental effort ratings for th
16、e first part of the experiment will be less than for the second part 40 8.2.3 Total duration of task completion. total duration of manual consultations and total number of errors will be less in the CAT condition than in the NoCAT condition . 40 The decrease in duration of scenarios and duration of
17、manual consultations as well as the decrease in subjective mental effort will be stronger in the CAT condition than in the NoCAT condition . 42 There will be a negative relation between SPM score and total duration of manual consultations. SPM score and total duration of all scenarios together and f
18、inally SPM score and total number of errors 44 Performance on model test I will be better in the CAT condition; performance differences between CAT and NoCAT will be larger on model test II than on model test I . 44 Types of error 45 0.2.4 8.2.5 8.2.6 0.3 Discussion 51 9.1 Discussion of the Experime
19、ntal Method 51 9.1.1 Use of scenarios . 51 9.1.2 “Framing“ 51 9.1.3 Scenario button . 52 9.1.4 Written information . 52 9.1.5 External validity of the learning environment 52 9.1.6 3PTY descriptions in the Table of Services 52 9.1.7 Implementation . 52 9.1.8 The user interface . 53 9.1.9 Use of * an
20、d # . 53 ETSI ETR*ZhL-4 96 3400855 014L45 872 Page 5 ETR 261 -4: October i996 9.2 Discussion of Results 53 9.2.1 Subjects who did not finish the experiment . 53 9.2.2 . Effect of practice . 54 9.2.3 Effects of transmitted conceptual model . 54 9.2.4 Relation between SPM score and performance 55 9.2.
21、5 Remembering the service commands 55 9.2.6 Understanding the functionality of a service 55 9.2.7 Types of error 55 1 O Conclusions and Recommendations . 56 10.1 Conclusions . 56 10.2 10.2.1 Account for subgroups 56 10.2.2 CLIP/CLIR . 57 10.2.3 Three party calling . 57 10.2.4 Auditory feedback 57 10
22、.2.5 10.2.6 10.2.7 10.2.8 Recommendations and Further Study . 56 Conceptual models of the functionality of services . 57 Avoid written scenario descriptions . 57 Future research on age-related differences 57 Research on conceptual models . 57 History 58 Page 6 ETSI ETR*261-4 96 3400855 0141746 709 E
23、TR 2614: October 1996 Blank page ETSI ETR*Zb1-4 9b m 3400855 0141747 b45 m Page 7 ETR 261 -4: October 1996 Foreword This ETSI Technical Report (ETR) has been produced by the Human Factors (HF) Technical Committee of the European Telecommunications Standards Institute (ETSI). ETRs are informative doc
24、uments resulting from ETSI studies which are not appropriate for European Telecommunication Standard (ETS) or Interim European Telecommunication Standard (LETS) status. An ETR may be used to publish material which is either of an informative nature, relating to the use or the application of ETSs or
25、I-ETSs, or which is immature and not yet suitable for formal adoption as an ETS or an LETS. Introduction The Technical Committee for Human Factors has prepared this ETSI Technical Report to report publicly its work on the assessment and definition of a harmonized minimum man-machine interface for th
26、e access and control of public network based supplementary services. It is intended to complement ETS 300 738 8. This ETR constitutes part 4 of a multi-part ETR (“Assessment and definition of a harmonized minimum Man-Machine Interface (MMI) for accessing and controlling public network based suppleme
27、ntary services“), whose parts have the following titles: Part 1: “General approach and summary of findings“; Part 2: “Literature review - Memory and related issues for dialling supplementary services using number codes“; Part 3: “Experimental comparison of two MMls - Simulated UPT access and prototy
28、pe ISDN supplementary services“; Part 4: “Experimental comparison of the effect of categorized and non-categorized formats within user instructions“; Part 5: Part 6: “Experimental comparison of the CEPT and GSM codes schemes“; “Survey of existing PSTN, ISDN and mobile networks, and a user survey of
29、supplementary service use within Centrex and PBX environments“; Patt 7: “Experimental evaluation of draft ETS 300 738. Page 8 ETSI ETR*261-4 Yb 3400855 0141748 581 = ETR 261-4: October 1996 Blank page ETSI ETRM261-4 1 Scope This multi-Dart ETSI Technical 96 m 3400855 0141747 Y18 W Page 9 ETR 261-4:
30、October 1996 Report (ETR) presents the results of the research work conducted to develop a European Telecommunication Standard (ETS) defining a harmonized minimum man-machine interface (MMI) for the access and control of public network based telecommunications services, and in particular supplementa
31、ry services. This part 4 of the ETR describes the experimental comparison of two forms of user instruction manual, a categorized form and a non-categorized form. The experiment considered user Performance and preferences within the basic user procedures provided to access a sample set of supplementa
32、ry services. The experiment explored differences between a user manual structured to support and reflect a user model of supplementary services (categorized) and a user manual which is structured to reflect the necessary user procedures (non-categorized). The experiment also allowed a comparison bet
33、ween the performance of younger and older subjects. 2 References For the purposes of this ETR, the following references apply: 131 141 Bennett RW Man Machine interface (MMI) of the mobile station (MS) (GSM 02.30)“. ETS 300 738: “Human Factors (HF); Minimum Man Machine Interface (MMI) to public netwo
34、rk based supplementary services“. ETR 261 -2: “Human Factors (HF); Assessment and definition of a harmonized minimum man-machine interface (MMI) for accessing and controlling public network based supplementary services; Part 2: Literature review - Memory and related issues for dialling supplementary
35、 services using number codes II. Fischer G (i 991): “The importance of models in making complex systems comprehensible.“ In MJ Tauber Assessment and definition of a harmonized minimum man-machine interface (MMI) for accessing and controlling public network based supplementary services; Part 1 : Gene
36、ral approach and summary of findings“. 3 Definitions, symbols and abbreviations For the purposes of this part of the ETR, the definitions, symbols and abbreviations given in part 1 36 of the ETR apply. 4 Theoretical Background This clause consists of four subclauses. In 4.1 the usability of already
37、existing supplementary service-like features is examined. Next, a theoretical framework is presented which serves to explain some of the observed phenomena (see subclause 4.2). Thereafter, specific aspects of elderly people using supplementary services are discussed in subclause 4.3. Finally, a numb
38、er of research questions and hypothesis are formulated in subclause 4.4. It should be noted that experimental research into usability of phone based interfaces is limited and much of the work is unpublished (Schumacher, 1992) 29. For that reason the current study must be regarded as an explorative o
39、ne. 4.1 Usability of Existing Features and Functions Modern private branch exchange systems (PBX; private telephony networks) already off er many of the features soon to be covered by ISDN supplementary services. However, several authors have pointed to the fact that most subscribers do not make use
40、 of the wide-ranging functionality of their terminals (Bennett Frankhuizen, 1983 ll; Jones, 1990 17; Neumeier, 1990 22; Roberts Root Truijens, 1985 34). There are a number of possible causes for this. The most straightforward explanation is that users do not need the functions. The perceived costs o
41、f learning to use a service (too much effort reading a manual or exploring the device, loss of time) simply do not counterbalance the benefits (Dooling reduction of the number of keys; guiding the user by clear visual feedback. According to Neumeier the only solution to users infinitely searching fo
42、r the desired function is reducing the number of available functions. In addition, users might be confused by a large number of keys. Instead of “one function-one key“ there is the soft-key concept: the relation between functions and keys is context dependent. Finally, Neumeier considers small Liqui
43、d Crystal Displays (LCD) actually inappropriate to give visual feedback. A large-screen graphical interface would be preferable. There are some remarks to be made with respect to the first and last principle. Simply reducing the number of available functions is a kill or cure solution. Assuming that
44、 a large number of functions is in fact necessary, improving search strategies is another option. Moreover, constructing comprehensive texts on a small screen LCD is possible, but will require creative thinking on the part of user interface designers. Jones (1990) 17, who conducted a more rigorous a
45、nalysis, lists a number of difficulties of numeric command languages: - lack of task structuring; - lack of contextual information; - lack of perceptual cues; - demands on memory and problem solving abilities. In the field of Human Computer Interaction (HCI) the solution to the problem of memorizing
46、 commands was found through the invention of menu-based and later on graphical dialogues on the screen. This meant that the commands could be displayed semi-permanent. However, phone based interfaces provide auditory “displays“ only. Menu presentation is necessarily serial and may turn out to be len
47、gthy in the case of an appreciable number of functions. Moreover, auditorily displayed menus may place heavy demands on short term memory, thereby limiting elderly people especially. Visual displays are more appropriate for the parallel presentation of menu-items (Schumacher, 1992 29). However, even
48、 PBI+ displays are still small (less than 40 characters). So, if it is decided to use visually displayed menus, the minimal interface may in fact turn out to be not so minimal after all. Bennett and Klinger (1 990) l conducted interviews with professional and managerial employees of companies that u
49、sed several varieties of PBX. No one used an “appreciable“ number of features unless their job required that they do so. (it is not clear what Bennett from TC-HF members informal observations with PBXs, it appears to be approximately three to five out of ten to fifteen.) After provision of an instruction booklet, they understood and readily followed the instructions. However, the actions they performed would always be arbitrary and mysterious to them. It appeared that most of them had little faith in their understanding of what was “really happening
