There are premeditated interactions, unconscious interactions, reactive interactions and spark points. Different initiators can benefit from different interfaces.
Premeditated interactions cover the ones where the user knows what he or she wants to do before doing it. This would include opening a document, scrolling to a section, applying an effect.
Reactive and Flow
Reactive interactions happen in response to using the system where the user more or less follows the needs of the system, such as clicking a OK/Cancel button or further refines a search.
Spark points cover moments where the user wants to do something which may or may not be part of the system and which may or may not have been “sparked” by the system or reading text on the screen. The most system-inclusive type of spark point interaction is where the user reads something and wants to know more about it by looking it up in an online reference work. It can be systematically unrelated such as where what sparks the user is a movie and the user would like to see it in the theater that day.
There are also external sparks which may prompt the user to do something else on the computer entirely or leave the computer and come back later. Such sparks need to be catered for by having the system be welcoming on return. This can be by remembering location and presenting context to help the user ‘get into” where he or she was with minimum of wasted time or thought.
Spark point examples include: What is this? Who is this? What is this in £/Celsius or other unit I understand? What is this in my language? What was this again – it was introduced earlier in the text… When was this? – They are things the author or editor could necessarily have anticipated.