Firm foundation in the main hci principles, the book provides a working
9 3 H U M A N F AC TO RS A S HCI T H EO R I E S 3.1 Human Information Processing
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Human Computer Interaction Fundamentals
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3 H U M A N F AC TO RS A S HCI T H EO R I E S 3.1 Human Information Processing Any effort to design an effective interface for human–computer inter- action (HCI) requires two basic elements: an understanding of (a) computer factors (software/hardware) and (b) human behavior. We will look at the computer aspects of HCI design in the second part of this book. In this chapter, we take a brief look at some of the basic human factors that constrict the extent of this interaction. In Chapters 1 and 2, we studied two bodies of knowledge for HCI design, namely (a) high-level and abstract principles and (b) specific HCI guidelines. To practice user-centered design by following these principles and guidelines, the interface requirements must often be investigated, solicited, derived, and understood directly from the tar- get users through focus interviews and surveys. However, it is also possible to obtain a fairly good understanding of the target user from knowledge of human factors. As the main underlying theory for HCI, human factors can largely be divided into: (a) cognitive science, which explains the human’s capability and model of conscious processing of high-level information and (b) ergonomics, which elucidates how raw external stimulation signals are accepted by our five senses, are processed up to the preattentive level, and are later acted upon in the outer world through the motor organs. Human-factors knowledge will particularly help us design HCI in the following ways. • Task/interaction modeling: Formulate the steps for how humans might interact to solve and carry out a given task/problem and derive the interaction model. A careful HCI designer would 3 0 H U M A N – C O M P U T E R I N T E R A C T I O N not neglect to obtain this model by direct observation of the users themselves, but the designer’s knowledge in cognitive science will help greatly in developing the model. • Prediction, assessment, and evaluation of interactive behavior: Understand and predict how humans might react mentally to various information-presentation and input-solicitation methods as a basis for interface selection. Also, evaluate inter- action models and interface implementations and explain or predict their performance and usability. 3.1.1 Task Modeling and Human Problem-Solving Model The HCI principle of task/interaction modeling was helpful in under- standing the tasks required to accomplish the ultimate goal of the interactive system. For instance, a goal of a word-processing system might be to produce a nice-looking document as easily as possible. In more abstract terms, this whole process of interaction could be viewed as a human attempting to solve a “problem” and applying certain “actions” on “objects” to arrive at a final “solution.” Cognitive science has investigated the ways in which humans solve problems, and such a model can help HCI designers analyze the task and base the interac- tion model or interface structure around this innate problem-solving process. Thus for a smaller problem of “fixing the font,” the action could be a “menu item selection” applied to a “highlighted text.” There are several “human problem-solving” models that are put forth by a number of researchers, but most of them can be collectively summa- rized as depicted in Figure 3.1. This problem-solving process epito- mizes the overall information-processing model. In general, human problem-solving or information-processing efforts consist of these important parts: • Sensation, which senses external information (e.g., visual, aural, haptic), and Perception, which interprets and extracts basic meanings of the external information. (As a lower level part of the information-processing chain [more ergonomic], we take a closer look at these and how they relate to HCI in Section 3.2.) • Memory, which stores momentary and short-term infor- mation or long-term knowledge. This knowledge includes 31 H U M A N FA C T O R S A S H C I T H E O R I E S information about the external world, procedures, rules, rela- tions, schemas, candidates of actions to apply, the current objective (e.g., accomplishing the interactive task success- fully), the plan of action, etc. • Decision maker/executor, which formulates and revises a “plan,” then decides what to do based on the various knowledge in the memory, and finally acts it out by commanding the motor system (e.g., to click the mouse left button). Figure 3.1b shows the overall process in a flowchart. Once a prob- lem is defined and identified as one that needs to be solved (simply by the user’s intention), it is established as the top goal. Then a hierarchi- cal plan (Figure 3.2) is formulated by refining the goal into a number of subgoals. A number of actions or subtasks are identified in the hope of solving the individual subgoals considering the external situation. By enacting the series of these subtasks to solve the subgoals, the top goal is eventually accomplished. Note that enacting the subtasks does not guarantee their successful completion (i.e., they may fail). Thus the whole process is repeated by observing the resulting situation and revising and restoring the plan. Information Define a problem Gather knowledge Consider possible actions Create plan Execute plan Observe results (a) (b) Repeat process (problem not solved...) Problem solved (Terminate process) Sensation Perception Decision Action Short term (Working Memory) Long term Memory Download 4.23 Mb. Do'stlaringiz bilan baham: |
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