The necessity for building a sophisticated human-machine interface for our Intelligent Tutoring System, called CIRCSIM-Tutor, has motivated us to explore natural language text understanding and generation. One complex task for the generator is crafting a response to student initiatives. A student initiative occurs when a student takes control of the tutoring session temporarily by saying something that forces the tutor to change the course of action and respond to the new situation. A question asked by the student in itself is considered to be one kind of initiative. We have analyzed tutor responses to student initiatives and developed twelve classes of tutor responses to be used in CIRCSIM-Tutor.
K4-st-84-1: I don't think I understand the question.indicates that this sentence comes from the fourth keyboard session, that the student is typing, that this is the 84th turn, and that it is the first sentence in that turn. In this case, the initiative belongs to the category which corresponds to features including when student does not understand something in the instruction from the tutor.
The session starts by describing a clinical scenario, in which some kind of perturbation disturbs the blood pressure. For example a mechanical heart pacemaker all of a sudden stops working properly and the heart rate is increased to 90 beats/ minute. The student is asked to make predictions about the changes experienced by four physical (haemodynamic) variables and three neurally controlled variables. The student is supposed to complete the predictions in three phases: Direct-Response (DR), Reflex-Response (RR) and Steady-State (SS). The DR phase includes the direct physical effects of the perturbation before the reflex begins to counteract the effect. The RR phase encompasses the changes brought by the reflex system to neutralize the effect. The SS phase shows the net effect of changes due to the direct effect of the perturbation and the changes made due to negative feedback.
Analysis of our transcripts shows that the tutor responses to student initiatives can be classified as follows:
We discuss these classes one by one with the aid of examples. The examples are extracted from different transcripts. We have expanded some of the abbreviations used by the tutor and the student in order to make the examples easier for our readers to understand.
1.a. Convey Information Hint (CI-Hint) 1.b. Point to Information Hint (PT-Hint)The CI-Hints directly convey information to the student. For example:
EX. 1.a. K25-st-161-1: Yes... so then you're saying that because reflex responses, for instance in map, are different than in the Direct Response that all/some/only that/ variable in Steady State reflect that in the Direct Response? K25-tu-162-1: For any parameter that you look at across the three columns, ss almost always follows Direct Response (when Direct Response and Reflex Response are changing in different directions).
The PT-Hints point to pertinent information but do not explicitly convey information to the student. How the tutor points to a piece of information can be seen in the following example:
EX. 1.b. K12-st-36-1: Yes I guess I am not sure then what happens to Total Peripheral Resistance K12-tu-37-1: What is the primary mechanism of control of Total Peripheral Resistance?
EX. 2. K13-st-48-1: If Stroke Volume decreases every time, Heart Rate increases, how can Cardiac Output ever increase K13-tu-49-1: What are the two parameters that determine Cardiac Output?. K13-st-50-1: Stroke Volume and Heart Rate K13-tu-51-1: Can you write the simple equation that relates Cardiac Output, Stroke Volume and Heart Rate? K13-st-52-1: Stroke Volume times Heart Rate = Cardiac Output K13-tu-53-1: Good. K13-tu-53-2: Then if Cardiac Output is up and Stroke Volume is down what must have happened? K13-st-54-1: Heart Rate increases more than Stroke Volume decreases K13-tu-55-1: Right, that's exactly what happens.
EX. 3. K6-st-60-1: Does the direct affect steady state more than the reflexes? K6-tu-61-1: Yes.
EX. 4. K4-st-48-1: How about the RAP, which may have an effect on how much blood is reaching the ventricle. K4-tu-49-1: Definitely, RAP affects ventricular filling.
EX. 5. K13-st-56-3: I am not sure if 120bpm is fast enough to cause that. K13-tu-57-1: Probably not. K13-tu-57-2: But more to the point, both tpr and cc change only when the reflex alters the activity in the ans (autonomic nervous system). K13-tu-57-3: And since dr is BEFORE the reflex can act, both must be 0 in dr. K13-tu-57-4: Let's go on to the next column.
EX. 6. K13-st-24-1: Cc increases maybe K13-tu-25-1: No maybe's allowed.
EX. 7. K12-st-46-1: Does the rate of blood removal from the central veins mean that blood entering the right atrium, if so i think venous return does go up immed. K12-tu-47-1: We need to get our terminology straight
EX. 8. K12-st-62-2: I'm just hesitant to say what comes first. K12-st-62-3: I'll go with tpr i to slow blood flow back to heart (i don't really like this idea) K12-tu-63-1: Well let's see if we can get at the first question I asked and then we'll come back to TPR.
EX. 9. K5-st-102-2: But I'll bet that's not right. K5-tu-103-1: Well you're right in your bet. K5-tu-103-2: Stroke Volume decreases because Cardiac Contractility decreases. K5-tu-103-3: That doesn't mean that RAP has to be decreased! K5-tu-103-4: Let me remind you again of the vascular function curve. K5-tu-103-5: Does that help? K5-st-104-1: RAP I. K5-tu-105-1: Would you explain. K5-tu-105-2: You're right but I just want to hear what you'r thinking.
EX. 10. K5-st-45-1: I don big pause here K5-ti-46-1: Need help?
EX. 11. K12-st-100-4: But I am confused with the role of decreased Toatal Peripheral Resistance and Right Atrial Pressure. K12-tu-101-1: I think that you haDr. Michael. K12-tu-101-2: I think that I have kept you long enough. K12-tu-101-3: Thanks very much for your help.
EX. 12. K5-tu-87-1: So? K5-st-88-1: I don't understand. K5-tu-89-1: How does CC D affect CO?
Figure: Response Length (content) by Initiative Categories.
Where 1d, 2a, 2b, and 3a are the categories coming out of Sanders' classification of student initiatives: 1. student asks a question, 2. student finds it hard to understand, 3. student requests repair, 4. student does repair, 5. student hedges, 6. student makes an explicit backward reference, 7. student takes initiative with respect to hardware/ software environment, 8. student asks administrivia type questions and the response length is calculated in terms of the number of sentences.
In this paper we have tried to analyze different transcripts to extract certain information regarding the tutor's attitude and tutoring style, especially when the tutor is engaged in responding to the student initiatives. We undertook this study in order to design responses to student initiatives. We have developed twelve classes of tutor responses. Most of them are based on intuitive criterion. The next question is what factors are responsible for producing conceptually different responses.
Li, J., Seu, J. H., Evens, M. W., Michael, J. A., and Rovick, A. A. (1992). Computer Dialogue System (CDS): A System for Capturing Computer-Mediated Dialogue. Behavior Research Methods, Instruments, and Computers, vol. 24, no. 4, pp. 535-540.
Sanders, G. A., Evens, M. W., Hume, G. D., Rovick, A. A., and Michael, J. A. (1992). An Analysis of How Students Take the Initiative in Keyboard-to-keyboard Tutorial Dialogues in a Fixed Domain. Proceedings of the Fourteenth Annual Meeting of the Cognitive Science Society. Indiana: Lawrence Erlbaum Associates, pp. 1086-1091.
1This work was supported by the Cognitive Science Program, Office of Naval Research under Grant No. N00014-94-1-0338, to Illinois Institute of Technology. The content does not reflect the position or policy of the government and no official endorsement should be inferred. Back to text