Model Human Processor by Phoebe Barnett

Introduction

phoebe_mb — 2015-10-06 12:08:51 UTC

The Model Human Processor (MHP) attempts to portray the user of a computer system as a computer with memory areas and processors.

The MHP was developed by Card, Moran and Newell in their boom titled The Psychology of Human-Computer Interaction, published in 1983. The diagram below shows a very simplified version of the model.

Process

phoebe_mb — 2015-10-06 12:23:09 UTC

Information is received through the eyes and ears: this is the input. The information is then passed to the Working Memory by the Perceptual Processor. The Working Memory comprises two separate storage sections: one for visual images and one for auditory images. The Woking Memory also includes those sections of the Long-term Memory that are currently of interest to the users and those sections that are required so the current task can be completed. This process can be related to the process of loading data from a disk into RAM.

The Recognise-act Cycle of the Cognitive Processor can be related to the fetch-execute cycle. On each cycle the current contents of the Working Memory are used to trigger actions to be carried out by the Motor Processor.

The MHP draws on the appropriate information held in the Long-term Memory to enable a task or action to be completed. For example, the Working Memory could hold the information that 'a left click of the mouse is needed' but the information required to complete this process will be held in the Long-term Memory.

The Working Memory demonstrates the importance of a user's short-term memory for the successful completion of tasks. If the memory becomes full of information before a task or action can be completed then the user will have to pause or re-read supporting documentation. As a result of this the user will often breakdown a task into manageable sections. The software interface that is being used must enable this to happen. For example, menus should be hierarchically divided to ensure the user can select exactly what they are looking for.

Summary

phoebe_mb — 2015-10-06 13:22:29 UTC

The MHP draws an analogy between the processing and storage of a computer with the perceptual, cognitive, motor and memory activities of the computer user.

This is done by a visual or audible stimulus being captured by the user with the physical attributes of the stimulus being decoded. For example, a user's attention is drawn to a box on the screen. The response that is needed will then be interpreted by the user. A motor response if then initiated to satisfy the response needed, for example, the click of a mouse button.

Application

phoebe_mb — 2015-10-06 13:24:55 UTC

The model can be applied to many situations related to the use of computers. However, the application the model was developed for is that of the design of a user interface.

Examples of how the model can be applied to the design of a user interface include:

logically ordering inputs, possibly those required from the user
using an on-screen flashing cursor to show where data is to be input
using an audible stimulus (e.g. a beep sound) to indicate when an error has been made by the user.