BHS Memory and Amnesia Semantic Long-Term Memory

Semantic Memory Semantic memory is general knowledge of the world. Are dogs safe? What happens in a restaurant? Generalizations that can apply to a variety of situations – built from previous experiences.

Semantic Priming Priming – thinking about one concept brings related memories closer to awareness. People respond faster to a concept after it has been primed. The prime comes first, then the target (associated item), and response times (RTs) are measured.

Memory Structure Semantic memory is structured based on shared meaning, not prior associations. Similar concepts in terms of meaning are stored closer to each other. Semantic “closeness” is metaphoric, based on response times. Activation spreads to related items. A great deal of repeated use moves items from episodic to semantic memory.

Controlled Priming In general, priming is automatic (does not require conscious effort). Conscious expectations can change priming (Neely). In the Category Shift Expected condition, the prime signaled the appearance of a different category which was then primed. It took a while for the different expectation to develop so priming occurs after several trials.

Mediated Priming How far does activation spread during priming? Lion  Tiger  Stripes Does activation spread to Stripes via Tiger? This phenomenon is called mediated priming – smaller than regular priming. The further you go from the original prime, the smaller the activation and less likely the priming.

Semantic Interconnectivity No fan effect in semantic memory – more associations speed up, not slow down retrieval. Direct and indirect connections provide more ways to retrieve info, making it more reliable. As with episodic memory, inhibition occurs, but mostly during active retrieval, not when passively reading.

Semantic Memory is Embodied In addition to capturing abstract relationships among words, storage reflects how we relate to the world. Concrete nouns tend to activate the sensory cortex because they are things we see and feel – perceptual effort. Verbs tend to activate the motor cortex because they are things we do.

Categorization Similarity-based grouping in which two or more entities are treated as equivalent. Concept – a mental construct that contains information associated with an idea (a dog). Category – a class of concepts to which a set of assertions applies (a dog has four legs, may bite). Categories are generalized from repeated instances of concepts.

Properties of Categories Levels of categorization: Basic, subordinate (detailed), superordinate. We operate on the basic level most often – items on that level retrieved better & faster. Central tendency – there is an averaged ideal or best member of the category. Graded membership – some members are better than others (robin vs penguin)

Definition of the Category Categories are defined in different ways: Rules – things that are used at the beach, numbers divided by 2, kinship (bachelor). Shared features or family resemblance – birds, furniture. Categories defined by rules or specific features are called classical categories. Classical theories don’t explain graded membership and typicality effects.

Prototype Theory Categories based on similarity or shared features may arise inductively from unconscious mental statistics. The typical member may be a statistical average of all category members, called a prototype. This theory does not explain how categories change over time or how we know their extent. Caricatures emphasizing distinctive features are better for comparing across categories.

Exemplar Theory Rather than reasoning from a derived prototype, we use all category members to make decisions. Explains sensitivity to context effects (priming of pony mane greater than lion’s mane). Circularity is a problem How can members define a category if the category is needed to identify the members?

Explanation-Based Theory When a category is formed, people try to explain why its members go together. Why do wings and feathers go together? Feathers help creatures to fly. Ad hoc categories – explanations created for a group of objects (e.g., things that stink). Psychological essentialism – the items grouped form natural kinds based on their nature, pragmatics, or causality (purpose).

Stereotypes & Prejudice Stereotypes are categories for various groups of people. When use of a stereotype causes someone to treat an individual inappropriately that is prejudice. Use of stereotypes is natural and part of normal thinking, but we must monitor our use of them for fairness.

Ordered Relations Semantic Distance Effect – the time it takes to make a judgment is proportionate to their distance. Semantic Congruity Effect – items are easier to judge when they are similar with respect to some dimension. Serial Position Effect – items at either end are easier to judge than the middle.

Schemas & Scripts Commonly experienced aspects of life form schemas – these make it easier to understand new situations. What happens at a birthday party? What happens at a restaurant? Scripts are schemas with a sequence of events that occur in a stereotyped fashion. Organized in time, like a script for a play or TV show.

5 Primary Schema Processes Selection – which components are important and which are peripheral. Knowing what schema to apply to a situation tells you what to pay attention to (Droodles). Ambiguous passages are clarified by schemas (washing clothes). Abstraction – the surface form is converted to an abstract meaning. Drawings change in the direction of meaning.

Schema Processes (Cont.) Interpretation – We infer missing info during reading or movies based on the schema (e.g., on/off airplane, infer flight) Integration – When we receive info piecemeal, the schema lets us put it all together (e.g., mysteries). Reconstruction – fill in gaps at recall from schema (War of the Ghosts).

Scripts Temporally ordered schemas structured by the main components of the event. Preference for going in the forward order. It takes longer to read a script when the next step is further along in sequence. People scan the steps in the script. Even when parts are presented in random order they are remembered in proper order.

Limits on Schema Use Schemas are not always used. Causes may be inferred from schemas but not necessarily effects because a number of outcomes may be possible. When a schema is discredited, people will ignore it. Escaped convict/deer hunter schema changed when subjects were told the title was wrong – fewer schema-related intrusions.

Semantic Illusions How many animals of each kind did Moses take on the ark? 81% of UCSD students got this wrong. What was the famous line uttered by Louis Armstrong on the moon? 3 explanations: (1) general focus; (2) partial assessment; (3) similar language components giving illusion it is known.

Naïve Physics A semantic illusion of nonverbal memory. Mental models of how the world works do not conform to real life physics. Similar to Medieval theories of motion. Less likely to occur with moving models, more likely with static drawings. People set thermostat higher so it will heat the house faster – temperature accelerator. Vision involves emissions from eyes.