This paper presents an empirical study comparing the effectiveness of four different versions of an on-line database tutorial, each of which calls upon the student to perform a different kind of inference. The general-to-specific version presents instructions in the form of general rules, from which the students expected to infer how to apply the rule in the give context. The explanation-to-specific version supplies information about the functional organization of the database program in addition to general rules. The specific-to-specific condition gives an example of the use of a command; the student must infer how to apply the command in a slightly different context. The control version gives explicit instructions. The best performance on a post-test consisting of realistic tasks was obtained from the general-to-specific and explanation-to-specific conditions.

The effect of the graphical programming language FPL (First Programming Language) on the occurrence of conceptual bugs in programs written by novices was studied. The type and location for each bug, and the frequency for each type were all recorded following procedures developed in an earlier Yale University study of novice Pascal programming. The findings were compared with those of the earlier study, and suggest that FPL may help beginning programmers avoid some common conceptual errors in their programming.

When people learn such a complex skill as computer text editing, they are learning a set of goals and the plans for accomplishing those goals. In this experiment we examined the structure and development of simple text-editing goals and plans. Long interkeystroke times were found to be associated with plan boundaries. The longest times were found between keystrokes separating superordinate goals, whereas less significant time increases appeared between keystrokes at subgoal boundaries. Changes in the patterns of interkeystroke times showed plan restructuring with experience.

Research issues concerning human interaction with computers have become crucial because of dramatic increases in the number of computer users who have no formal mathematical, engineering, or computer science training. This review focuses on the state of the art in Software Psychology--the study of human factors in computer systems. One area of software psychology, the psychology of programming, is picked for an in-depth discussion of research results. This area was selected for its interest to the readers of the PROCEEDINGS OF THE IEEE. The review then discusses the methodological issues involved in performing experimental research in software psychology. Future trends are discussed both for the programming research reviewed here and for the whole field of software psychology. The conclusions identify multidisciplinary training and research as critical to further progress in this field.

An important part of communication is being able to point to an object without referring to its components or to the area surrounding it. How to do this is the problem of ostension. We observed many ostension errors in novices learning to use a full-screen text editor. Specifically, the novices erroneously tried to use keys that are appropriate for pointing when using a typewriter but incorrect in screen editors (e.g., space bar, backspace key, etc.), they frequently missed the location they intended by one character, they inadvertently pointed to the wrong occurrcnce of a string using a FIND command, they incorrectly specified boundaries by forgetting about “invisible” characters (e.g., formatting characters), and they mistakenly attempted to point to non-typing areas of the screen that were off-limits.

The organization of text editing behavior can be characterized by graph structures containing goals, subgoals, goal outcomes, and actions. Here we propose a model to represent the goals and plans of text editor users based on goal-fate analysis (Schank & Abelson, 1977). The representation captures relationships between a user's multiple goals and shows how errors can result from badly formed plans. We discuss some data from a psychological experiment which supports the hypothesis that text editing behavior is chunked into distinct plan units. The cognitive components of pause times between keystrokes were revealed by statistically removing the physical time required between keystrokes. Finally, we suggest how a system which builds goal-fate graphs from keystroke input might be useful in providing specific help information that is keyed to a user's intentions.

While programmers may differ in their assessment of the comprehensibility of a program, there are nonetheless some clear cut cases of programs that are truly difficult to understand. In this paper, we analyze three programs—two of which are relatively incomprehensible—using Halstead's Volume Metric, Propositional Analysis and Plan Analysis. We argue that only Plan Analysis provides a satisfactory explanation for why the programs in question differ with respect to understandability. Moreover, we suggest that a qualitative analysis, such as provided by Plan Analysis, is the desired type of evaluation: rather than simply providing a numerical ranking for programs, the qualitative analysis can pinpoint the troublesome area in the code and provide prescriptive information for correcting the difficulty.

Natural language would seem to have a strong effect on users' behavior with artificial command languages for interacting with computer systems.