Different Constraints in Design

In continuing my series on interface design I want to talk about chapter four of The Design of Everyday Things. Now this book isn’t strictly about designing web interfaces like the other book I am reading is, however this talks about design in general and gives the reader a lot of interesting things to think about.
One of the recent topics that I read about was design constraints and how they are used to prevent people from making mistakes with various objects. Here are some of the different types of restraints that are built into objects:

Physical Constraints-

Physical limitations constrain possible operations. Thus, a large peg can’t fit into a small round hole.

Semantic Constraints-

Semantic constraints rely upon the meaning of the situation to control the set of possible actions.

A good example would be when you are putting together a piece of furniture and know that while the knobs to a drawer could be screwed on in the inside they logically go on the front.

Cultural Constraints-

Some constraints rely upon accepted cultural conventions, even if they do not affect the physical or semantic operation of the device.

Logical Constraints-

Natural mappings work by providing logical constraints. There are no physical or cultural principles here: rather there is a logical relationship between the spatial or functional layout of components and the things that they affect or are affected by.

Ever since I read this section I have applied to do how items function and look at them to see what constraints are there. In fact it has consumed me a little, I was actually talking to a date about the design of a door. (Like they do in this chapter). And that the way it set up didn’t make sense and didn’t give the user any hints on how it operated.

Design is involved in everything we do.