4. Perception: Shape

As the short test earlier showed, people associate shapes with circumstance.

Starry shape tends to indicate 'Alert, look at this!' For instance you will often see 'bargain prices' in shops using sharp shapes.

Cloudy smooth shapes tend to indicate friendly information. For instance Speech bubbles.

So use these in an appropriate way - sharp shapes for alerts, smooth shapes for information.

Some symbols have an almost universal meaning, such as

An interface that uses these symbols the other way around would be truly confusing!