Reprinted by permission from lEEE TRANSACTIONS ON MAN-MACHINE SYSTEMS Vol. MMS-11, No. 4, December 1970 Copyright© 1970, by the Institute of Electrical and Electronics Engineers, Inc. PRINTED IN THE U.S.A. AI in CAI: An Artificial-Intelligence Approach to Computer-Assisted Instruction JAIME R. CARBONELL, member, ieee Abstract The main purpose of the research reported here is to powerful than existing ones, to prove that it is feasible, show that —a new and more powerful type of computer-assisted and to demonstrate by example some of its major capa- instruction (CAI), based on extensive application of artificial- bilities. In the course of this investigation, a set of com- intelligence (AI) techniques, is feasible, and to demonstrate some puter programs, system was written. of its major capabilities. A set of computer programs was written the scholar [I], and given the name scholar. Due to its complexity, only the scholar is capable of reviewing the knowledge of a stu- conception and educational aspects of this system (including an dent in a given context (e.g., geography of South Amer- actual on-line protocol) are presented in this paper. ica) by maintaining a mixed-initiative dialogue with him (AFO) In what may be called conventional ad /ioc-frame-oriented in a rather comfortable subset of English. Fig. 1 presents the data base consists of many "frames" of specific pieces CAI, fragment of text, questions, and anticipated answers entered in advance by a of a protocol taken on-line, demonstrating the teacher. By contrast, an information-structure-oriented (ISO) some of the basic capabilities of scholar. In this proto- CAI system is based on the utilization of an information network col, scholar starts typing after being called. The stu- of facts, concepts, and procedures; it can generate text, questions, dent's turn comes each time an asterisk is printed. He and corresponding answers. Because an ISO CAI system can also may respond to a question by scholar, direct a question utilize information network answer questions formulated by its to or such the student, a mixed-initiative dialogue between student and to scholar, state a command as halting, or computer is possible with questions and answers from both sides. changing the mode of the interaction. The student re- turns control to scholar by typing another asterisk and a carriage I. Introduction and Overview return. scholar can prompt the student, indicate when it does HE MAIN purpose of the research reported in this not understand him, detect misspellings, and answer the document is to introduce a new type of computer- student's question using acceptable English, scholar (CAI), many respects more assisted instruction in can also generate questions and evaluate the student's answers, deciding when these are correct, wrong, or only Manuscript received July 20. 1970. This work was supported in approximately or partially correct, and then take some part by the Office of Naval Research under Contract NOOOl4- It -69-C-6223. by the Air Force Electronics Systems Division under conditional actions. keeps track of content and changes Contract Ki9628-69-C-0298. and by the Advanced Research it on the basis of relevancy and time considerations. Agency F19625-C-0125. Project under Contract scholar does all this without specific and detailed direc- J. R. Carbonell is with Bolt Beranck and Newman, Inc.. Cam- bridge. Mass. 02138. tions, but rather by applying general criteria and pro- oarbonell: ARTII'IOI.U.-INTELUOKNCE approach to CAI 191 cedures to a body of "knowledge" about the subject be- from the student, thus using its semantic network for ing discussed. question-answering purposes. This explains why mixed- Conventional tutorial CAI systems depend for their initiative dialogues between man and computer are now operation on the utilization of ad hoc blocks of material, possible. The use of a semantic network' also facilitates usually called frames, entered in advance by the teacher. the two-way communication in a rather large and free The material in the frames usually includes paragraphs subset of English. of English text to be presented, specific questions with The research leading into the development of scholar their expected correct answers, perhaps some expected can also be considered as an investigation on an aspect incorrect answers, keywords, and anticipated branching of man-computer interaction, namely, the possibility of for a limited closed set of predictable alternatives for having mixed-initiative man-computer discourse. This each student's answer. Questions are more often than not mode of interaction is of interest for areas of application of the multiple-choice type. The student has no initiative other than CAL and can ask no questions. We like to call the CAI sys- The subject matter, geography of a given region, was tems based on detailed frames ad hoc- frame-oriented selected as being representative of verbally oriented sub- (AFO) CAI systems. jects with comparatively little inherent logical structure In contrast to the AFO approach, the approach to CAI and contextual algorithms. This type of subject seemed presented in this document can be defined as being in- to be among the hardest to treat in a generative way, formation-structure-oriented (ISO), since it is based on since its structure isrepresented by its descriptive seman- the utilization of a complex but well-defined information tics. Algorithmically, formal subjects like algebra or structure in the form of a network of facts, concepts, and analytic geometry present considerably fewer difficulties procedures as a data base. The elements of this network in terms of both their internal representation and their are units of information defining words and events in the natural language input-output. Success in dealing with form of multilevel tree lists. The elements of those lists them would not have implied immediate translation to are other words that in turn point to their respective verbally oriented subjects [4]. units, and so on. Fig. 2 is a pictorial simplified repre- Changing the region (e.g., Africa) to which geography sentation of a portion of a network of this sort in the procedures are applied presents no problem to scholar context of geography of South America. Each rectangle since only part of the semantic network must be updated. or plane is a unit with a name (Uruguay, Argentina, Changing the application to a different subject (e.g., South America, country, latitude) and a set of symboli- anatomy of the circulatory system) would mean an al- cally coded properties. most complete revision of the content of the semantic The perspective from a given word pointing to the network, but not of the program. Shifting to a more com- corresponding unit, with the elements in the properties putational or algorithmic topic (such as aspects of Span- pointing to other units, and so on, represents the "mean- ish syntax or analytic geometry) would still require prac- ing" of that word. In this sense, the network can be said tically no changes in the program but would imply a to be a "semantic" network. Semantic networks were first semantic network much richer in procedures than that of introduced by the pioneering work of Quillian [2], [3]. more descriptive subjects and procedures, such as to Fig. 3 is a small portion of the actual internal configura- conjugate Spanish verbs or to determine an 'intersection' tion of scholar's semantic network, presenting the unit in analytic geometry. for "latitude," and fragments of the unit for "Argentina." Artificial-intelligence techniques have played a major Observe that no specific pieces of text, questions with role in the development of scholar through its natural their predicted answers, errors, or anticipated branching language processing, utilization of semantic networks, form part of this information structure, as is the case in and question-answering procedures. Existing techniques the data bases of conventional AFO CAI systems. have been combined with original procedures for question In ISO systems, an executive program, almost com- generation and for handling the problems of context and pletely independent of the subject matter to which it ap- relevancy. plies, is now capable of probing the semantic network After some extensions and refinements, we contemplate in order to generate the material to be presented and the the application of scholar to practical situations with questions to be asked of the student. As shown in Fig. 1, large data bases. Because the content-free nature of the this program is at the same time capable of generating executive program forces a precise definition of pro- the corresponding answers to its own questions and of a cedures, scholar constitutes an ideal environment to in- certain degree of branching conditional on the student's vestigate pedagogical questions. responses, while maintaining a continuity of contexts and scholar is currently implemented in the bbn-lisp subcontexts. language in an XDS-940 time-sharing computer. This Furthermore, the data base of ISO CAI systems re- environment was selected principally because of its flects basic "knowledge" about the subject under discus- rather large virtual memory obtained through paging. sion; therefore, scholar can at any time accept questions Conversion to a larger and faster Digital Equipment to to REPHRASE YOUR STATEMENT. I CAN'T UNDERSTAND IT. "800300* " INCORRECT* "SCHOLAR) YOUR ANSWER IS INCORRECT. VERY GOOD. THE CORRECT ANSWER IS: 214000. THE AREA OF PARAGUAY IS APPROX 157000 SQUARE MILES. ♦♦♦♦+ + + +++ + + ++ + + + + + + + + + + + + + + + ++ + ++++++++ + + +++ + + + + +T-++ + + + THE POPULATION IN CHILE IS APPROX 8500000. PEOPLE TRUE OR FALSE? THE LANGUAGE IN BRAZIL IS FRENCH. HELLO. MY NAME IS SCHOLAR. I WILL HELP YOU IN REVIEWING RIGHT OR WRONG? THE GEOGRAPHY OF SOUTH AMERICA. THIS IS ABC REGIONAL "TRUE* HIGH SCHOOL. TODAY IS 04/29/70. "WRONG* YOU ARE CORRECT. YOU ARE CORRECT USE ONE OF THE FOLLOWING! THE LANGUAGE IN BRAZIL IS PORTUGUESE.