How do we store information for the long-term in memory? Memory Storage How do we store information for the long-term in memory?

Two issues Knowledge format - How, precisely, is the information being stored? Knowledge organization - How is the information arranged in memory?

Knowledge format What format is information stored in? The issues are similar to the mental imagery debate. Propositional Hypothesis

Dual-Code theory Paivio (1971) combines elements of propositional hypothesis and Baddeley’s working memory Verbal codes - abstract, amodal codes; possibly propositions Imagistic codes - analog codes based on sensory modalities

Knowledge Organization How is knowledge organized in memory? The debate parallels the imagery debate - is it organized categorically, or based on sensory modality.

Conceptual organization Intuitively, we believe we organize information by concepts. Concepts are discrete ideas, like “apple” or “red”. We then organized related concepts into collections called categories.

Conceptual storage How do we store and identify concepts? Feature theory - Categories are represented as lists of features, such as the concept STOP SIGN being represented as “red; octogon; at street corner” etc.

Prototype theory A concept is represented as the “average” of all its members. We recognize an object as being one of a given concept by comparing it to all of our stored prototypes and picking the one that’s closest Experiments show that, when presented with arbitrary categories, people rate the prototype as more typical than individual examples. How do we recognize very bizarre members of a category? (e.g., goofy Scandanavian chair; platypus)

Exemplar theory A concept is represented by the stored exemplars of all past instances of the concept that we’ve encountered. Easily accounts for how bizarre examples get recognized. Computationally realistic?

Two syntheses Prototype with exceptions - normal categorization works according to prototype theory, but we also store exceptions that deviate too much from the prototype. Core-prototype - We represent the core of a concept as its required features, and maintain multiple prototypes of examples that contain typical combinations of other features. Think of them as necessary and sufficient features.

Conceptual organization Hierarchy - the most popular notion is that of a conceptual hierarchy, where subordinate concepts inherit properties from their superordinate categories. Network - Concepts are arranged in a loosely organized network, where connections between concepts are based on the relatedness of those concepts.

Hierarchical models Semantic Network (Collins & Quillian, 1969)

Network models Spreading Activation - Information is not organized strictly in a hierarchy. It’s more of a hodgepodge.

Unitary Content Hypothesis Information in semantic memory is stored in an abstract, amodal representation with a structure based on concepts. The theory claims that this is not just true in the mind, but in the brain as well.