Mental Models for Producers"All our ideas and concepts are only internal pictures".
Ludwig Boltzmann (1899)
Theories of mental representations in general, and mental models in particular, deal with form and function of individual knowledge. The central question is how human beings represent information mentally, and how they use that information to interact with the world in adaptive ways. Users knowledge about computer systems are a specific type of mental representations. Mental representations have been investigated by researchers in philosophy, cognitive psychology and more recently cognitive science.
One of the most influential theories to be formulated in cognitive psychology in recent years is Johnson-Lairds (1983) theory of mental models. The theory seeks to provide a general explanation of human thought; at its core is the assertion that humans represent the world they are interacting with through mental models. Johnson-Laird credits Craik (1943) with the original statement of this idea. In order to understand a real-world phenomenon, a person has to hold a what Johnson-Laird (1983) describes as a working model of the phenomenon in his or her mind. Mental models are not imitations of real-world phenomena, they are simpler. They do not correspond completely to what they model Johnson-Laird argues that adding information beyond a certain level does not increase its usefulness. A mental model which explains all aspects of the phenomenon that a person interacts with is an appropriate one. In order to provide explanation, it has to have a similar structure to the phenomenon it represents; it is this similarity in structure which enables the holder of the model to make mental inferences about the phenomenon which hold true in the real world. Since the choice of structure is not arbitrary, but analogous to that of the phenomenon, the mapping relationship between mental models and the phenomena they represent is a referentially isomorphic one.
The theory of mental models demolished an assumption which was until then prevalent in psychological theories of reasoning: that humans employ a kind of mental logic, which is similar to the propositional logic employed by logicians, when making inferences about the world.
Most peoples reasoning is primarily influenced by the content-relatedness and form of the information presented. People are more likely to solve a problem correctly when they have relevant background knowledge which can be employed. They are more likely to relate relevant existing knowledge to the problem presented if the structure of the information presented is compatible with the structure of existing knowledge. Relevance and compatibility are defined in terms of meaning (i.e. semantic content) rather than logic (i.e. syntactic structure).
Johnson-Laird (1983) proposes that reasoning about a problem is facilitated if a person utilises a mental model that represents the relevant information in an appropriate fashion for the problem to be solved.
According to Johnson-Laird (1983), the theory provides a general explanation of human thought; however, its empirical support stems from experiments involving short reasoning tasks. Is it really applicable?
Following this theory, users ability to interact with a computer system depends on whether they have an appropriate mental model of the system. An appropriate model does not have to be complete and correct in every detail; all it has to do is explain the functions and behaviour of the system which are relevant to the user. The cueing and construction of such a model can be supported by the way in which information is presented to a user: form and content of information determine which existing models are cued, and how new information is mapped onto existing or new models through the mechanism of procedural semantics. Applied to HCI, this means that designers would have to identify suitable existing knowledge to be cued, and present relevant information about the system in the context and form which directs the model-building process towards the intended mental model.
More practicalIf I tell you that I recently ordered a steak at a restaurant, you might assume that I was met at the door by a host or hostess, seated, and presented with a menu. You assume these details, and others, that I never actually mentioned because they have a mental model of how restaurants operate. To illustrate the consequences of having a mismatched mental model, I describe a person who goes into a buffet restaurant and waits for someone to take their order. The person's mental model of how that restaurant operates doesn't match the actual situation, and he would experience confusion and frustration until he modified his original model to include buffets.
All mental models have a few key characteristics:
- Mental models include what a person thinks is true, not necessarily what is actually true.
- Mental models are similar in structure to the thing or concept they represent.
- Mental models allow a person to predict the results of his actions.
- Mental models are simpler than the thing or concept they represent. They include only enough information to allow accurate predictions.
Its important to distinguish between the conceptual model a description of what the application, site or service does and a mental model a description of how the application, site, or service is structured.
As the most abstract level of the interface, the purpose of the conceptual model is to leverage the users experience from the physical world to enable them to form accurate and useful expectations about what type of functionality or content is available. It helps them answer the question, is this thing a store, a brochure, a newspaper, a reporting system, or what?
Despite their abstract nature however, conceptual models invariably represent real world objects and experiences. For example, blogs are a like a diary, iTunes is like a jukebox, Microsoft Word is like a typewriter, and an ATM is like a bank teller. Although none of these models tell the user how something is likely to be organized or structured, they do tell them what types of transactions, features, objects, and capabilities are likely to be present.
By contrast, a mental model describes how a user expects a particular system or service to be organized. It helps them say, Given that this thing is a store, I expect there to be a place dedicated to product X, a space for product Y, and a place to complete my transaction. Of course, mental models are intensely individual things, varying from one user to the next. Therefore, a significant challenge is to discover the various mental models and then find consistent and predictable ways of reconciling and expressing them as a single, coherent information architecture.
We can portray mental models using several key parts:
- An image (needed if the mental model is of a physical thing)
- A script (needed if the mental model has a process)
- A set of related mental models
- A controlled vocabulary
- A set of assumptions
Reductionist Approach to Developing User Mental ModelsLook for similarities in the conceptual groups across user groups
Align conceptual groups into larger groups (mental spaces) based on:
Steps the users described
Similarity of conceptual groups
Together these larger groups form the mental model
.css file based on the work of Jeffrey Zeldman
Kelake is written by Clark MacLeod.
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