Direct Manipulation
Limitations
Direct manipulation regarding technology has several limitations.
Physical constraints include inability to see text or movement on the monitor, inability to use an input device such as a mouse, and inability to hear error messages, etc.
Semantic constraints include inability to understand the text and links on a web site. Be careful to not to use catch phrases that are exclusive to your field or the region where you live.
Cultural constraints include insulting content or content exclusive to the region where you live. For example, the University of Utah’s graduate school web site would not want to use exclusive or insulting text or images. They must be aware of insulting content.
Logical constraints include links that are not grouped properly such as when links about a corporation are spread throughout a page and/or not in proximity to each other. Lack of navigation in the home page (I don’t believe splash pages should EVER be used), or navigation that does not make sense create logical constraints for your poor users.
Computer Restraints
Computers have general interface constraints in that there is exponential growth in the amount of information each individual user deals with every day, so users often get confused where to go and how to use these tremendous resources. In addition, there is a growing range of computer users with their wide variety of skills, needs, and expectations; so different users are able to use different technologies.
So how do we account for all these needs and expectations? The following are some theories from experiential cognition and interaction design that may help.
What is Experiential Cognition?
Experiential Cognition is how we become immersed when we encounter an interface. Hopefully, the interface has been designed such that we have already experienced a similar interface. For example, if we encountered a microwave with a door that opened on top rather than in front, it would cause much difficulty for many of us. It is the same for a web site; if we create a web site where all the links are strictly on the bottom of pages, then our users will not be able to proceed through the site.
Questions we ask when first encountering an interface1
- Which parts move; which are fixed?
- Where should the object be grasped? What part is to be manipulated? What is to be held? Where is the hand to be inserted? If it is speech sensitive, where does one talk?
- What kind of movement is possible: pushing, pulling, turning, rotating, touching, stroking?
- What are the relevant physical characteristics of the movements? With how great a force must the object be manipulated? How far can it be expected to move? How can success be gauged?
- What parts of the object are supporting surfaces? How much size and weight will the object support?
How can we apply these questions to hypermedia?
It’s Not About the Interface, It’s About the Interaction
Make Visible the Invisible2
- Make steps visible and understandable
- Create a good display with not too much clutter and emphasize the necessary steps
- Consider using sound for visibility and to give information about the source and action
Designing interaction rather than interfaces means that our goal is to control the quality of the interaction between user and computer: user interfaces are the means, not the end.
The challenge is to create new tools that both augment and complement human capabilities. But you must consider how much information and how many kinds of interfaces users already encounter. Be innovative but use fairly familiar interfaces.
Designing Interaction, Not Interfaces3
- No single interaction technique works best in all contexts, and the best solution is to provide a range of interaction techniques and let users decide which to use.
- Separate information from tools used to create them
- Design should focus both on the higher level of context of use and the lower level of sensory-motor phenomenon.
- A paradox of HCI is that the best interface designs are invisible: they are not noticed by users who find the interaction “natural.”
HCI is not the science of user interfaces, just as astronomy is not the science of telescopes. HCI needs interfaces to create interaction, and we should focus on describing, evaluating and generating interaction, not interfaces.
References
1 Norman, D. A. (2002). The design of everyday things. New York: Basic Books.
2 Norman, 2002
3 Beaudouin-Lafon, M. (2004). Designing interaction, not interfaces. Paper presented at the AVI ’04.