CHAPTER 12
cognitive models

EXERCISE 12.1

Recall the CCT description of the rule INSERT-SPACE-2 discussed in Section 12.2.2:

	(INSERT-SPACE-2
	IF (AND (TEST-GOAL insert space)
		(TEST-CURSOR %LINE %COL) )
	THEN (  (DO-KEYSTROKE 'I')
		(DO-KEYSTROKE SPACE)
		(DO-KEYSTROKE ESC)
		(DELETE-GOAL insert space) ))

As we discussed, this is already proceduralized, that is the rule is an expert rule. Write new 'novice' rules where the three keystrokes are not proceduralized. That is, you should have separate rules for each keystroke and suitable goals (such as GET-INTO-INSERT-MODE) to fire them.

   (INSERT-SPACE-BEGIN-SET-MODE
	IF (AND (TEST-GOAL insert space)
		(TEST-CURSOR %LINE %COL)
		(TEST-NOTE in command mode ))
	THEN (  (ADD-GOAL get into insert mode)))
	
   (INSERT-SPACE-END-SET-MODE
	IF (AND (TEST-GOAL insert space)
		(TEST-GOAL get into insert mode))
	THEN (  (DO-KEYSTROKE `I')
		(ADD-NOTE in insert mode)
		(DELETE-GOAL get into insert mode)))
	
   (INSERT-SPACE-DOIT
	IF (AND (TEST-GOAL insert space)
		(TEST-NOTE in insert mode)
		(TEST-CURSOR %LINE %COL))
	THEN (  (DO-KEYSTROKE SPACE)
		(ADD-GOAL get into command mode)))
	
   (INSERT-SPACE-CLEAN-UP
	IF (AND (TEST-GOAL insert space)
		(TEST-NOTE in insert mode)
		(TEST-GOAL get into command mode))
	THEN (  (DO-KEYSTROKE ESC)
		(DELETE-GOAL get into command mode)
		(DELETE-GOAL insert space)
		(DELETE-NOTE in insert mode)
		(ADD-NOTE in command mode)))

EXERCISE 12.2

One of the assumptions underlying the programmable user model approach is that it is possible to provide an algorithm to describe the user's behaviour in interacting with a system. Taking this position to the extreme, choose some common task with a familiar interactive system (for example, creating a column of numbers in a spreadsheet and calculating their sum, or any other task you can think of) and describe the algorithm needed by the user to accomplish this task. Write the description in pseudocode. Does this exercise suggest any improvements in the system?