mental models in cognitive science

Engineering Psychology User Interface Lab.

P. N. Johnson-LairdUniv. of Sussex

Cognitive Science 4, pp.71-115., 1980

조성식


Introduction Inference and Mental Models Meaning and Mental Models Images, Propositions, and Mental Models Levels of Desciption Experiments on Mental Models and Propositional

Representations Conclusions

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Cognitive science needs theories that both cohere and correspond to the facts.

Three questions : The mental processes that underlie ordinary reasoning and the question of

what rules of inference they embody the representation of the meanings of words and the question of whether

they depend on a decompositional dictionary or a set of meaning postulates the form of mental representations and the questions of whether images

differ from sets of propositions

☞ Their answers all implicate the notion of a mental model

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Syllogism : Aristotle All A are B, All B are C, then All A are C

Figure effect

Atmosphere effect negative → negative or affirmative, particular → particular or universial

Three theories in the last few years Ericson : Euler circles

All A are B ↔ All B are A , Some A are not B ↔ Some B are not A

a1 → B b1 → A a2 → B b2 → -A

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Criteria for evaluating theories of syllogistic inference account for the systematic mistakes and many valid inferences should be readily extendable provide an account of how children acquire the ability to make inferences should be at least compatible with the development of formal logic☞ three theories fare pooly on these criteria → a different approach needed

Syllogistic inference as the manipulation of mental models

An evaluation of the mental model theory of inference it provides an account of both the figural effect and the systematic errors can be generated so as to represent all sorts of quantified assertions illuminates the way in which children learn to make inferences entirely compatible with the development of formal logic

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Meaning postulate stipulates the semantic relations between words the notion that lexical items (words) can be defined in terms of relations

with other lexical items

Propositional representation we store concepts in a non-language form of propositions. we can bring the concept into our working memory to put it into

language.

Two problems for meaning postulates

Procedures for manipulating mental models FUNCT(%0, 1%) DX, DY

Luke

MarkMatt.

B A

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Propositional representations People store concepts in a non-language form of proposition. A proposition is a complete statement. It can be true or false. a dog -> object, “ That dog looks like my dog” -> proposition “The boy was having a birthday party, and the girl had no present to give

him.” P1 : ( HAVE boy birthday party ) P2 : ( POSESS girl present ) P3 : ( NEGATIVE P2) P4 : ( GIVE girl present boy)

Image A mental image is an experience that resembles the experience of perceiving

some object, event, or scene when the relevant object, event, or scene is not actually present to the senses.

Owing to the fundamentally subjective nature of the phenomenon, there is little evidence either for or against this view.

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Images versus Propositional representations An image is distinct from a mere representation of propositions

Mental processes for images are similar to the perception of an object or a picture a coherent and integrated representation amenable to mental transformations Represent objects

An image is epiphenomenal and propositional in form Mental processes for P.R. are similar to the perception of an object or a picture When propositions are represented in the form of a semantic network, then the

representation is coherent and integrated. A P.R. is discrete and digital rather than continuous, but can represent continuous. Propositons are true or false of objects. The critics of imagery : An image does not introduce any new information, it merely makes the stored

desciption more accesible and easier to manipulate. Image and P.R. differ on the function served by representation ( 4th characteristics) but share many properties They are similar and transformed into one another => controversy is neither fundamental nor resolvable.

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Anderson’s theorem on “Mimicry” A propositional theory can mimic an imagery theory.

Imaginal theory : A stimulus is encoded as an image. Propositional theory : A stimulus is encoded as a set of proposition. propositions → propositional encoding inversely → original stimulus → imaginal

encoding → image → rotate image → rotated image → imaginal encoding inversely → (rotated) stimulus → propositional encoding → the set of propositions(rotated)

the set of propositions(rotated) → propositional encoding inversely → rotated image (rotated) stimulus → imaginal encoding → rotated image

=> There is no guarantee that a direct method can always be found for two theories. ( indeterminate state -> a single P.R. , many different M.M. )

=> A theory of P.R. does not yield the same equivalence class of representations as the class yielded by the theory of mental models. There is difference between them.

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The characteristics of propositional representations A proposition can be treated as a function from the set of possible worlds onto

the set of truth values. Grasping a proposition is analogous to compling a function, whereas verifying

a proposition is analogous to evaluating a function. Arbitrary syntactic structure : K(α,β) , (αKβ) , or (α,β)K The propositional description of a complicated state of affairs may consist of a

large number of propositions. => In a semantic network, propositions about the same entity are gathered

together.

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The charateristics of mental models Propositional representation is a desciption. (true or false w.r.t. the world) Human being do not apprehend the world directly but possess internal

representations of it. P. R. is true or false with respect to a mental model of the world. ( This functional difference could be only distinction between P.R. and M.M.) A model represents a state of affairs in the world. Its structure is not arbitrary. A single P.R. will suffice, but many alternative models will be needed for the

discourse. Images correspond to the components of models that are directly perceptible in

the equivalent real-world objects. Model may underlie thought processes without necessarily emerging into

concious-ness in the form of images. Images and models are not necessarily equivalent to sets of propositions?

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The reconstruction of a theory at a lower level of description- A psychological description should be a functional one.- Whole of the original theory of spatial inference can be reconstructed in

way of program formulae. ( A is on the right of B -> AT(A,1,6), AT(B,1,2) )

Any psychological theory can be based (vacuously) on propositional representations- Any plausible theory of any psychological phenomenon is propositional.

How to give the notion of a “Propositional representations” an emperical content

- A propositional representation is based on symbols that correspond in a one-to-

one fashion with the lexical items of natuaral language. - The same advantage in programming language is obtained from high level procedures for manipulating both models and propositional

representations.

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Hypothesis There appear to be different levels of representation (differ in kind)

superficial understanding : propositional representation profound understanding : mental model

Experiments continuous vs discontinuous : continuous were better recalled

Determinate vs indeterminate determinate premises were better recalled If subject remembers the original meaning, they can remember it verbatim.

Assumtional results Mental models are constructed from propositional representations. Amount of processing : mental model > P.R. P.R. : not easy to recall, but if recalled, it can be recalled verbatim M.M. : easy to recall, but no guarantee to be recalled verbatim

69% correct 42% correct 60% correct

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First, there are indeed distictions to be drawn between P.R. and

M.M..

Second, there are likewise distinctions to be drawn between a

decompositional semantics and a set of meaning postultes.

Third, it is possible to account for the psychological principles

underlying deductive reasoning.

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mental models in cognitive science

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