While it’s hard to predict “R”, it's clear that the goal is to reduce "P" and "M". Wait for a computer to respond to input (R) - vary.Move hands to keyboard from mouse (or vice-versa) =.Point with a mouse (excluding click) (P) = 1.1 seconds.Perceptual Processor - 100 milliseconds.Follow a coherent conceptual model so that once part of the interface is learned, the same principles apply to other parts.Use words to describe the desired action (e.g., "click here" or use labels in front of perceived objects).Follow conventional usage, both in the choice of images and the allowable interactions.Or direct message like "see more", "more info", "read more", etc. For example, clickable buttons or links have distinctive visual style. In touch screens, where is no hover highlight affordance, this is even more important. If an element is clickable, for example, it must appear that way, or a user may never try clicking it. Users shouldn't have to guess or scrub the page to find out where they can click. To maximize the perceived affordance of "clickability", color and underline the link text, make buttons look like buttons. By giving people cues (mostly visual) about what they can do with a particular object, you make it more likely that they will take that action. Think about affordance cues when you design. He referred to the idea of perceived affordances: if you want people to take action on an object, whether in real life or on a computer screen, you need to make sure that they can easily perceive, figure out, and interpret what the object is and what they can and should do with it. In 1988 Don Norman modified the idea of affordances in his book The Design of Everyday Things.
He described affordances as action possibilities in the environment.
James Gibson wrote about the idea of affordance in 1979.