The Human–ComputerDialogue in LearningEnvironmentsJEAN-CLAUDE TARBY

Laboratoire Trigone, Institut CUEEP, Universite Lille 1, 59655 Villeneuve d’Ascq, France

Received 28 September 1994; accepted 8 February 1996

ABSTRACT: Among learning environment design tasks, this paper is specifically inter-ested in the student–computer dialogue specification and management. We show that itis possible to define decisional latitude intervals in which the student may work. Thespecification of dialogue is made through a design method called Diane/ that allowssimulation of the evolution of the student’s level and evaluation a priori of the designedsoftware. q 1997 John Wiley & Sons, Inc. Comput Appl Eng Educ 5: 29–39, 1997

INTRODUCTION must be used together. The work which is presentedhere concerns the last two aspects. It studies moreprecisely the human–computer dialogue. (DialogueThe design of an intelligent tutorial system (ITS)

includes four main elements: is defined here as the set of possible student interac-tions in the application and as the visible feedbackproduced by the application.) Two problems stillj The design of the expert module. The role of

this module is to analyze the student’s results exist today in this domain. First is the design of thisdialogue, and second is the implementation and theand transmit them to the teacher module.management of the dialogue.j The design of the student model module, which

Designing an ITS poses problems such asis the computing representation of the student.It contains the student’s knowledge, beliefs,

j What the student can do?etc.j What are the possible ways for the student to

j The design of the teacher module. This moduleobtain a result?is the computing representation of the teacher.

j How should the ITS be built? What are theOne of its roles is management of the lessontopics that students must learn and what are thesequences.topics that they can discard?

j The design of the user interface (UI) . The UIis very important because it is the obligatory

After design, it is necessary to implement the dia-way for the student to use the ITS.logue. Once more, some problems appear:

These four elements require several competen-j How should the constraints of lesson chaining

cies (psychology, linguistics, pedagogy, etc.) thatbe represented?

j How can the student be helped when he needsq 1997 John Wiley & Sons, Inc. CCC 1061-3773/97/010029-11 help?

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j How can one be sure that the student does only show the OPAC data model that we use withDiane/. The last part shows how Diane/ allowswhat it is permitted for him to do?us automatically to manage the dialogue and contex-tual help through the UI.This article shows what kind of solution can be

found.This work is based on a design method called

Diane/ [1,2] . The method is based on thinking THE DIANE/ METHODabout the interactive user-driven applications. Itallows us to specify The Diane/ method [1,2] specifies human–com-

puter dialogue for interactive user-driven applica-tions with variable-in-time decisional latitude.j the human–computer dialogue,Diane/ is based on task decomposition in relation

j the distribution of the tasks between the humanto the types of users and associated goals (hierarchi-and the machine,cal planning [3]) . It specifies the task distribution

j and the decisional latitude of the user into theat all levels (from goals to processes) and offersapplication. (The decisional latitude is the stu-the possibility to implement dialogues according todent freedom of action within the application,the user’s ability by integrating implicitly some useri.e., the set of possible actions during a workcharacteristics (knowledge level, frequency use,session.)etc.) in these decompositions. The dialogue is speci-fied through three main concepts: operations (i.e.,

Diane/ covers the entire cycle of the applications set of processes) , precedences (i.e., temporal links( from design to implementation and automatic between operations) and procedures (i.e., detailedmanagement ) . It is based on the decomposition task descriptions with the possible sequences of op-of tasks into goals, subgoals, etc., and it integrates erations within the tasks) . These three concepts aresome characteristics of users. It can be applied to represented through a formalism [2] and includemany domains such as the learning environments attributes which can handle very complex dialogues.presented here through a lecture apprenticeship We chose Diane/ because it takes both the pro-example. cess and data points of view into account, while

Management of the dialogue is difficult, because including the user’s characteristics in the design.the student must work with a large decisional lati- Diane/ provides great compactness of the dialoguetude while not transgressing the dialogue’s con- specifications, and the possibility of seeing the ap-straints. For example, the student can choose an plications through different abstraction levels.exercise to learn a word, but he must not start a These characteristics do not exist together in thelesson if his level is insufficient. following:

Our work simultaneously uses an object-orientedapproach and sequencing rules (not detailed in this

j Human–computer dialogue formalisms, sucharticle) that represent the temporal sequences be-

as state diagrams and Petri nets. With thesetween the processes. These rules are issued from

formalisms, specification complexity increasesthe Diane/ specifications and are managed by the

exponentially with the number of states. Thus,dialogue controller. The OPAC data model [2] pro-

it is very difficult to write comprehensive speci-vides data capable of management through their ex-

fications.ternal and internal representations at a basic level.

j Object-oriented design methods which ‘‘di-The Diane/ method connects these data by associ-lute’’ the processes through the objects (anyating them to processes (operations) that areglobal vision of the application’s behavior; forgrouped in sets (procedures) taking the goals andexample, when a process uses several differentthe level of the user into account (beginner, ad-objects) .vanced, security clearance, etc.) . With the OPAC

j ‘‘Classic’’ design methods (not object-ori-data model and the object-oriented implementationented ) which are often dedicated to particu-of the Diane/method, we can directly obtain opera-lar types of application (management, fortional user interfaces from the specifications.example ) .In the first part, we present briefly the Diane/

method; in the second part, we discuss the problemof the human–computer dialogue specification Diane/ is one of the few current methods which

allows one to evaluate the decisional latitude ofthrough the teacher module. In the third part we

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an application. This evaluation is not formal, but which is present in the minimal procedure. Thus,we are sure that the student can only do whateverDiane/ diagrams highlight dialogue distribution.

The designer can see immediately if the user can we permit him to do.use an operation or what operations can be enabledafter one of the user’s actions. Another reason for

Operationsour choice is that Diane/ does not impose any par-ticular formalism for implementation. We chose an An operation is an elementary process or a processobject-oriented approach to implement our tool, that can be possibly decomposed into suboperations.since it respects software engineering criteria and it In addition to its contents and name, a Diane/ oper-is also widely used in the HCI domain. ation possesses conceptual attributes [Each opera-

tion also possesses classic attributes such as pre- orpostconditions, current operation’s status (locked,

Procedures running, etc.) , interruptability (Y/N), etc.] :

A procedure is the formal and detailed descriptionj A mode that indicates if the operation is inter-of a task which describes the sequencing of the

active (the computer requires data from theoperations of this task [1] . Thus, a procedure is auser to execute the operation) or not (automaticset of operations (see below) which may be linkedmode—only the computer controls the opera-by precedences (see below). Diane/ uses threetion).kinds of procedures: minimal, foreseen, and effec-

j A type: an operation must be either requiredtive. It associates one minimal procedure, one fore-( the operation must be executed to reach theseen procedure, and several effective procedures forgoal) or optional ( the operation may or mayeach task. Foreseen procedures reflect a coherentnot be executed without interfering with reach-use of available operations to reach a goal. Theying the goal) .are used for learning and help. Effective procedures

reflect real activity in situ or during simulations. j A trigger that is either the user or the computer.Minimal procedures are the central core of the hu- In the case of a user-trigger, the operation mayman–computer dialogue. They are extracted from be executed as many times as the user wantsforeseen and effective procedures, and they contain (on the condition that the operation is not lim-both the set of necessary or possibly usable opera- ited in the number of execution).tions to reach a goal, and minimal control of theuser by the computer. Operation Constraints The operations may submit

Minimal procedures contain both minimal and two kinds of constraints:maximal decisional latitude:

j Constraints on the number of triggerings.j Minimal decisional latitude: Minimal proce-

j Constraints on the suboperations. This con-dures contain all the controls that must be straint only concerns the optional suboper-checked by the machine for the task to end ations, because the required operations must bewell. The student is obliged to respect the as- executed. For example: If the student triggerssigned controls. Those correspond first, to op- the exercise operation (Fig.1) , he can chooseerations and sequences which must be exe- only a form of answer ([1,1] constraint in an-cuted, and second, to validations of constraints swer operation Å only one). After choosing aon the operations. form of answer, the other optional suboper-

j Maximal decisional latitude: Besides the as- ations (in the answer operation) become disa-signed controls, the student can do whatever bled until the next triggering of the answer op-he wants. He is his own manager during the eration (which number of triggering is limitedwork sessions. He possesses a maximal latitude to 3).in the limit of the possibilities authorized bythe minimal procedure.

Precedences

Because a task is a set of operations which areNote that all the foreseen and effective proce-dures have to remain coherent with the minimal executed over a period of time, it is necessary to

give a structure to link temporally these operations.procedures. A foreseen or effective procedure canonly restrict the maximal decisional latitude interval This type of link is called precedence.

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Figure 1 Example of operation constraint.

Precedence allows the linking two operations. for effective use of the application. The secondcase is useful to optimize tasks. For example:Diane/ distinguishes two types of precedence:If the two operations display the text and readaloud the text are not linked, and if the user

j Permanent precedence: Two operations whichexecutes them consecutively (display the textare linked by a permanent precedence (noted r)then read aloud the text) , the system recordsmust be executed in the order given by the prece-this sequence, and can propose this sequencedence. Triggering of other operations betweenby default the next time (note that this sequencethe end of the first operation and the beginningremains optional) .of the second operation remains possible.

j Indicative precedence: When two operations are Important remark: The presence of a precedencedoes not involve the triggering of operations. If Alinked by this type of precedence (noted rrrú),

it means that the user can execute these two and B are linked by a precedence (A r B), it means‘‘A must be executed for B to be enabled,’’ but notoperations in any order, but it is preferable for

him to respect the given order. These opera- ‘‘If A is finished, then trigger B.’’ Our approachis user-oriented (the user may trigger B), but nottions could already have been executed in this

order. The first case is useful for learning. A machine-oriented (the machine triggers B immedi-ately after A).beginner can thus follow the advised sequences

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HUMAN–COMPUTER DIALOGUE AND data in an elementary way, and Diane/ managesdata in the context of the application. For example,TEACHER MODULEOPAC objects can display a client number, selectcharacters in a text, or record a date. However, dateThe teacher module has many roles: lesson and ex-

ercise sequences, choice of correct exercises with validity control, with regard to the application’sdata, is processed by the Diane/ procedures andregard to the student’s level, student model updat-

ing, etc. Among these roles, we take an interest in operations.An OPAC datum is an object with three parts:the chaining representation and in the management

of the student’s decisional latitude. So, we searchhow to represent the chainings, but not why these j an abstraction, which contains the data repre-

sented by the OPAC (for example, a name ofchainings exist, which is within the competence ofthe teachers and psychologists. person, a question, a list of books, etc.);

j a presentation, which (1) proposes externalAn apprenticeship domain is generally brokendown into lessons that are associated with goals. representatives with regard to the abstraction

and links between the OPAC object and theEach goal may be decomposed into subgoals, sub-subgoals, etc. For example, lecture apprenticeship Diane/ operations and (2) manages, in an ele-

mentary way, the associated external represen-may be decomposed into ‘‘word apprenticeship,’’‘‘sentence understanding,’’ etc. The goals may sub- tation (selection, scrolling, etc.) ; and

j a control, which (1) provides a set of basicmit chaining constraints, for example ‘‘word ap-prenticeship’’ before ‘‘sentence understanding.’’ In methods (in the object context) to manage the

OPAC data (creation, suppression, display,the same way, the exercises which compose thegoals submit constraints. With Diane/, each lesson etc.) independently of the Diane/ operation

and (2) maintains consistency between the ab-(i.e., each goal) is associated to a procedure thatcorresponds to a set of exercises. An exercise is straction and the presentation.decomposed into operations with attributes that de-scribe the student’s decisional latitude. Figure 2 gives an example of compounded

OPAC data. It is compounded of several OPAC dataWe showed that Diane/ specifications giveboth the minimal and the maximal student’s deci- (name, address, phone, and title) which can be

also compounded (for example, the address OPACsional latitude. This characteristic is fundamentalin our approach. By this mean, it is possible to data) . If an operation uses a subabstraction (for

example, the phone number) , it must get it fromcontrol precisely the student’s interactions. Thefreedom interval may be modified before (adapt- the highest abstraction level OPAC data. This

OPAC data gets its subabstraction from the associ-ability ) and after (adaptativity ) the final imple-mentation. These modifications may be made ated sub-OPAC which provides the methods to pro-

cess the operation.manually or automatically and are the result of theexpert module’s and student’s interactions. With An interesting aspect of the OPAC model is the

possibility of producing different external represen-these possibilities, we can simulate the student’slevel evolution and evaluate the software a priori tations from the same specification with regard to

different students. For example, we attach an OPAC(lesson choice, exercise sequence, etc.) .for each exercise (Figs. 3 and 4). This OPAC in-cludes the question and answer for the exercise.These two components are OPACs themselves. TheTHE OPAC MODELquestion OPAC contains many representations andthe answer OPAC contains all the authorized an-Diane/ does not require a special implementation

technique for processes and data. The current ver- swers. For example: After displaying the text ofFigure 3, the teacher module asks the student tosion incorporates an object-oriented model called

OPAC [2] derived from the PAC model [4] . The name Annie’s cat. At least two question forms arepossible:OPAC model structures data into elementary or

compounded objects capable of providing and man-aging their external and internal representations. j Textual question: The teacher module writes

the question on the screen. We can suppose thatThis model also provides a set of methods (in theobject context) for their manipulation. The aim of only one textual form is sufficient: for example,

‘‘What is the name of Annie’s cat?’’ But it isthis model is to unload basic data management intothe data themselves. The OPAC model manages possible to have many forms: for example,

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Figure 2 Example of compounded OPAC.

‘‘Give me the cat’s name,’’ or ‘‘There is a cat j Sonorous question: The teacher module readsthe question aloud. In the same way, one sono-beside Annie. What is its name?’’ When the

question is going to be asked, the teacher mod- rous form may be sufficient, but it is possibleto use another: for example, the voice of theule chooses the right form with regard to the

student level based on the student model. It can teacher, of the student’s parents, of another stu-dent, etc.also choose a form at random to avoid tiring

the student with an invariant question.

In these two forms the question is fundamentallythe same. Only its external representation changes.Note that the two forms may be completed by avisual trace. With the textual form, the teacher mod-ule highlights (or underlines) the read words. Withthe sonorous form, it highlights the cat during thequestion. These two forms may be implemented asparticular question forms.

In the same way, the answer is unique. The stu-dent may choose several forms to answer:

j Entering the name with the keyboard: Supposethat the name is ‘‘Kitty.’’ The student can enter‘‘KITTY,’’ ‘‘Kitty,’’ ‘‘kitty,’’ ‘‘k i t t y,’’ etc.Only the good answers must be accepted. Thetextual answer OPAC abstraction contains‘‘kitty,’’ for example. The control transformsthe entered string in lower-case letters andcompares this string with ‘‘kitty.’’ If the stu-dent entered ‘‘k i t t y,’’ the comparison fails.The Diane/ operation, which called the exer-

Figure 3 Example of text used for exercises. cise, recovers the error and sends it to the

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Figure 4 Exercise OPAC containing different question and answer forms.

teacher module which explains, for example, plays a roll of supervisor with regard to its sub-OPACs. When control is ordered to display thethat a name does not contain spaces.text, it delivers this order to its components,j Clicking on the name of the cat in the text: Thewhich in turn deliver it to their components.hyperwords are used here. The text of the storyControl is also capable of finding what the hyp-contains many hyperwords, which are OPACs,erword is that the student clicked on.on which the student can click with the mouse

(or any other pointer) . Hypermedia techniques j The contents of the text is split into a statictext and a set of words (i.e., hyperwords) thatare used in this case. For example, if the student

clicks on the word ‘‘miaule,’’ he hears the cat’s can react to the student’s interactions. Eachhyperword is an OPAC that contains the wordmew, when during an exercise the hyperword

returns the associated OPAC for the exercise and possibly pictures, sounds, animations, etc.to extract what it needs (text, sound, picture, j A set of exercises is associated with each text.animation, etc.) . We showed that each exercise is an OPAC with

sub-OPACs that manage the question and thej Clicking on the picture of the cat’s plate: Inthe same way as the hyperword, we use a answer (Fig. 4) .hyperpicture.

At the moment, such a compound structure isIn these three forms the answer is the same. Only static, since its links are definitively established (ex-

the form of the answer changes. cept modifications from the designer) . A dynamicThe OPAC data model can manage compound structure, in which the exercises are not directly

information. For example, it can manage the fol- linked to the text but called by the teacher modulelowing structure for the lecture apprenticeship with regard to the student’s competences, would be(Fig. 5 ) : an interesting extension of our work.

j A set of books is used for exercises. Eachbook is composed of texts (e.g., stories ) . Pre- HUMAN–COMPUTER DIALOGUE ANDsentation of the book OPAC can display the AUTOMATIC INTERFACE MANAGEMENTcoversheet, the picture of the book, etc. Ab-straction is composed of the sum subabstrac- Complete user interfaces can be generated fromtions and other data, e.g., the book’s title, the OPAC data and dialogue specifications. Theythe author, the number of pages, the editor. can be directly executed by our tool through anControl can give information on the book inference engine which simultaneously uses(getAuthor, getNumberO f Pages, etc.) and chaining rules ( i.e., implementation of prece-keeps the consistency between abstraction dences) and Diane/ objects. (Diane/ objects areand presentation. objects which represent Diane/ concepts.) This

implementation was chosen to manage help andj A text contains different items (text, pictures,sounds, animation, etc.) . The text OPAC only modify specifications without altering the dia-

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Figure 5 Example of OPAC structure for lecture apprenticeship.

logue controller (only the sequencing rules and tions through a dedicated editor which generatesthe sequencing rules, all necessary objects (opera-the Diane/ objects are modified) . The combined

use of Diane/ objects, chaining rules, generated tion objects, procedures objects, OPAC objects,etc.) , and the user interface. Then the applicationinterfaces, and the inference engine allows us to

manage the application automatically through the is ready to run.interface. For this, the dialogue controller regu-larly inspects the sequencing rules to detect opera-tions that must modify their state (use of forward AUTOMATIC MANAGEMENT OF HELPchaining) . These operations modify their statesaccording to a predefined, individual state diagram Richard [5] defined logical use as the use of the

application by the user, and working use as use by(Fig. 6) . Every state modification is reflected inthe interface and is supported by the operation the software designer. For example, if the software

designer regroups the Create Client and the Create(which requests the state change) as well as byits representatives on the interface (which perform Article operations in one menu, it is considered to

be a working use menu. If these operations are dis-the state change) . These modifications are possi-ble because of the links created during generation tributed through the Client and Article menus, they

are logical use-oriented.of the interface. This way, an operation that hasbecome enabled for the student asks its representa- Since Diane/ is based on a decomposition in

goals and tasks with regard to the user, it respectstives to reflect this change. In the same way, ifan operation has become disabled, it causes its logical use. The help function can be managed auto-

matically in the same manner, since it depends onrepresentatives to become disabled for the student.But if the student interacts on a widget, it sends dialogue specifications [6]. As the generated se-

quencing rules give us the feasible sequences ofa message to ask the associated operation to per-form the process requested by the student. In the processing, we can obtain, by forward chaining, the

list of operations available since the last interactiontwo cases, the processes are performed withoutany designer interaction, since the links are issued occurred (‘‘working use help’’) . On the other hand,

hierarchic decomposition and backward chainingfrom the generation.The Diane/ object-oriented implementation give us the path to a desired goal (‘‘logical use

help’’) . The use of sequencing rules allows us tospares the designer from writing a new dialoguecontroller for all new applications. This is the answer questions such as, ‘‘Why is this widget disa-

bled?’’ ‘‘What is the consequence of this action?’’same inference engine whatever the applicationis. When the designer wants to realize an applica- ‘‘How can this widget be enabled?’’ ‘‘How can the

working processes be finished?’’ etc. The answerstion, he has only to write the Diane/ specifica-

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HUMAN–COMPUTER DIALOGUE 37

Figure 6 State diagram of an operation.

take the context of the request into consideration, er’s view of the application (hierarchic plan-ning).i.e., the value of data and the states of the operations

at that moment. To respond to these types of ques- j Human–computer dialogue specification, whichtions, the dialogue controller inspects the states, pre- includes some user characteristics.conditions, and postconditions of the operations as

j Automatic contextual help management andwell as the value of data and the sequencing rules. automatic human-computer dialogue manage-

ment, which derive directly from the specifica-tions, i.e., the user interface and help functionare always coherent with the specifications.CONCLUSIONMoreover, even if a user or the designer mod-ifies the specifications, the interface and help

The Diane/ method allows very complex dialogue management do not need to be modified.specification. Through its implementation in ob-jects, sequencing rules and OPAC data model, A prototype has already been implemented withDiane/ provides: Smalltalk/V for Windows (Fig. 7) . At the present

time, it is able to manage automatically the interfaceand help function as presented in this article. Ourj ‘‘Logical use’’ for processes and data: This

makes the specifications coherent with the us- tool also enables the designer to

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Figure 7 General working of the tool.

j increase the level of abstraction for specifications softwares [7]. With our tool, we are certain that theas well as for the validity of the applications, student can do only what he is authorized to do.

Moreover, the student has complete freedom in thej decrease the time of implementation,

interval of decisional latitude which is given in thej adapt in a very simple manner processes ac-

specifications.cording to different user types.

In comparison with software such as Authorwareor Toolbook, Diane/ and the associated tool avoidthe need to write all of the elementary elements thatSimulation of the student’s level evolution is pos-

sible and allows one to evaluate a priori the designed are necessary with such systems. For example, with

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Authorware, the designer must write all of the ac- REFERENCEStions that the system will do with regard to the user [1] M.-F. Barthet, Interactive Software and Ergonomicsactions. With Diane/ it is not necessary, because (in French). Dunod Editions, Paris, 1988.the inference engine manages human–computer di- [2] J.-C. Tarby, ‘‘Automatic human–computer dialogue

management from conceptual specifications,’’ PhDalogue. In other words, it is possible to implementthesis ( in French), University Toulouse I, France,Diane/ specifications with systems such as Au-September 1993. Available from the author.thorware. In this case, the designer must first trans-

[3] E. D. Sacerdoti, A Structure for Plans and Behaviour.late the precedences in process sequences; and sec-Elsevier Computer Science Library, New York, 1977.

ond, translate the OPAC data in user interface ele- [4] J. Coutaz, ‘‘Human–computer interface: design andments with scripts that define their behaviour with implementation.’’ PhD thesis ( in French), Universitethe user. But in all cases, it is absolutely impossible Joseph Fourier, Grenoble, France, 1988.totally to manage logical use help with these sys- [5] J.-F. Richard, ‘‘Working use and logical use’’ ( in

French). INRIA Research Report no. 202, Inria,tems, because these systems do not allow one toFrance, April 1983.have access to their human–computer management

[6] J.-C. Tarby, ‘‘Management of the student–computermodule.dialogue in learning environments,’’ 1995 WesternTwo major areas still require further re-Multiconference on Simulation, January 15–18,

search: improvement of help (we intend to trans- 1995, Las Vegas.late our inference engine into Prolog) and devel- [7] J.-C. Tarby, ‘‘The automatic management of human–opment of the automatic generation of the user computer dialogue and contextual help,’’ EW-

CHI’94, St Petersburg, August 2–6, 1994.interface.

BIOGRAPHY

Dr. Jean-Claude Tarby received his PhDin computer science from the University ofToulouse I in 1993. Currently, Dr. Tarby isan assistant professor at the Trigone Labora-tory of University Lille 1. Dr. Tarby’s re-search program is focused on the automaticgeneration and management of user inter-faces from conceptual and functional speci-fications. His interests include hypermedia,

multimodal, human–computer dialogue, user interface designmethods, CSCW, and groupware.

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