Week 4: Gestalt Principles and HCI Design Principles

from Don Norman

How do the HCI design principles relate to Gestalt theory? I think they both start from the logic/psychological perception of users. When we design digital messages, we should ask ourselves “what will it be in users’ mind?” instead of “what will it be in fact?” As Norman said, “The real question is about the perceived affordance: Does the user perceive that clicking on that location is a meaningful, useful action to perform?”

In the final analysis, it is still the issue about "user-centered design."

Some important notes from the readings:

Gestalt Principles:
Figure and Ground
The terms figure and ground explain how we use elements of the scene which are similar in appearance and shape and group them together as a whole. Similar elements (figure) are contrasted with dissimilar elements (ground) to give the impression of a whole.

Similarity
The principle of similarity states that things which share visual characteristics such as shape, size, color, texture, value or orientation will be seen as belonging together.

Proximity / contiguity
The principle of proximity or contiguity states that things which are closer together will be seen as belonging together.

Continuity
The principle of continuity predicts the preference for continuous figures. We perceive the figure as two crossed lines instead of 4 lines meeting at the center.

Closure
The principle of closure applies when we tend to see complete figures even when part of the information is missing.

Area
The principle of area states that the smaller of two overlapping figures is perceived as figure while the larger is regarded as ground. We can reverse this perception by using shading to get our message across.

Symmetry
The principle of symmetry describes the instance where the whole of a figure is perceived rather than the individual parts which make up the figure.


How new users understand what to do: Four principles for screen interfaces:
1. Follow conventional usage, both in the choice of images and the allowable interactions.
2. Use words to describe the desired action (e.g., "click here" or use labels in front of perceived objects).
3. Use metaphor.
4. Follow a coherent conceptual model so that once part of the interface is learned, the same principles apply to other parts.

Human-Computer Interface Design seeks to discover the most efficient way to design understandable electronic messages.
You Should Use the Eight Golden Rules of Interface Design:

1.Strive for consistency
*consistent sequences of actions should be required in similar situations
*identical terminology should be used in prompts, menus, and help screens
*consistent color, layout, capitalization, fonts, and so on should be employed throughout.

2.Enable frequent users to use shortcuts
*to increase the pace of interaction use abbreviations, special keys, hidden commands, and macros

3.Offer informative feedback
*for every user action, the system should respond in some way (in web design, this can be accomplished by DHTML - for example, a button will make a clicking sound or change color when clicked to show the user something has happened)

4.Design dialogs to yield closure
*Sequences of actions should be organized into groups with a beginning, middle, and end. The informative feedback at the completion of a group of actions shows the user their activity has completed successfully

5.Offer error prevention and simple error handling
*design the form so that users cannot make a serious error; for example, prefer menu selection to form fill-in and do not allow alphabetic characters in numeric entry fields
*if users make an error, instructions should be written to detect the error and offer simple, constructive, and specific instructions for recovery
*segment long forms and send sections separately so that the user is not penalized by having to fill the form in again - but make sure you inform the user that multiple sections are coming up

6.Permit easy reversal of actions

7.Support internal locus of control
*Experienced users want to be in charge. Surprising system actions, tedious sequences of data entries, inability or difficulty in obtaining necessary information, and inability to produce the action desired all build anxiety and dissatisfaction

8.Reduce short-term memory load
*A famous study suggests that humans can store only 7 (plus or minus 2) pieces of information in their short term memory. You can reduce short term memory load by designing screens where options are clearly visible, or using pull-down menus and icons