Mental models are how the mind represents real, remembered, hypothetical, or imaginary situations. Models are like…

**…mental sketches.**A simple sketch doesn’t retain all the details of what it represents — consider what’s left out in a stick figure sketch of a person. Sketches are*iconic*, i.e., they they preserve the overall structure of what they represent. Similarly, sketches are*homomorphic*representations, i.e., they include only pertinent details (stick figures routinely fail to represent a person’s fingers and internal organs). Models are both*iconic*and*homomorphic.***…an architect’s blueprints.**A blueprint is a concise representation of a*possibility —*a building that could potentially occur in the real world. Blueprints are*coherent*, i.e., it’s impossible to create a blueprint of a building in which a basement is above the roof. Similarly, models represent*coherent possibilities.***…diagrams.**Diagrams are powerful because you can learn new things by*scanning*them. Hence, new insights*emerge*from diagrams. Likewise, diagrams can represent*abstract*ideas, e.g., you can use a symbol in a diagram to represent abstract ideas — such as a star in a map to represent the capital of a city. Diagrams can even represent negation using, e.g., this symbol: ?. So, models can be scanned to yield*emergent inferences*; and they can represent*abstract concepts*.**…comic strips.**Comic strips don’t represent actions and events directly; instead, they represent discrete, critical points of a sequence of events in chronological order. Similarly, models are*discrete*and*finite*: they don’t represent infinite sequences, because cognitive resources are finite.