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Memory (2) 1 Three points for today 1. We distinguish between two types of knowledge – Procedural and Declarative. 2. Knowledge comes in several unit sizes, from small (concept) to big (schema), with units at one level connecting to form next level. 3. How these units are processed, especially how connections among units are formed, influences learning. Memory (2) 2 1. Types of Knowledge Memory (2) Two Types of Knowledge Declarative Knowledge • Knowledge that you know you have and that you can report (“declare”) Procedural Knowledge • Knowledge of how to do things (e.g., tie your shoes, do arithmetic). 3 Memory (2) 4 2. Knowledge Units (a) Sizes Memory (2) Declarative Knowledge Units Concept • Smallest unit of knowledge (not of meaning) • A concept is a mental representation of a category of things in the world (e.g. DOG) • Concept allows you to decide whether a stimulus is a member of the category • Issue: nature of the representation – prototype? Set of exemplars? Feature list? 5 Memory (2) Declarative Knowledge Units Proposition • Smallest unit of meaning that has a truth value • A proposition asserts some quality or behaviour of some entity • Basically, Subject, Verb, Object or Quality • e.g., The dog barked; The dog is brown; The dog wore sneakers 6 Memory (2) Declarative Knowledge Units Schema • Stored knowledge structure that influences perception and comprehension • Capture important information about people, situations and events • What usually happens? What is usually present? When does an event usually occur? • Acquired slowly; difficult to modify 7 Memory (2) Procedural Knowledge Units Production • If CONDITION holds, then perform ACTION • Anderson argues that all behaviour can be modeled as sequences of productions • A sequence of productions can become automatic. This is proceduralization. 8 Memory (2) Procedural Knowledge Units Script • due primarily to work of Roger Schank in artificial intelligence. • a script is like a schema for a process • detailed, because computer programs won’t run unless you specify everything necessary • more recent versions allow scripts to be created as needed from stored components (episodes, actors, settings) 9 Memory (2) 10 2. Knowledge Units (b) Connections Memory (2) Network Models of Knowledge Two basic types of models: Local Representation • nodes in the network represent concepts Distributed Representation • nodes don’t represent anything; concepts are represented in patterns of activation 11 Memory (2) Local Representation Models Quillian & Collins (1969) TLC • Teachable Language Comprehender • Hierarchical organization • Nodes are empty. They are placeholders in the network. • All links the same length. • ISA links and property links 12 Memory (2) 13 Local Representation Models Collins & Loftus (1975) • less hierarchical version of TLC • structure of network reflects person’s experience rather than objective scientific information • explained typicality effects • introduced very important concept of spreading activation for retrieval of information • explained priming effects Memory (2) Distibuted Representation Models Parallel Distributed Processing (PDP) • ‘neural network’ or ‘connectionist’ models • models have units (neurons) and weighted connections (axons/synapses) • concepts are represented as patterns of activation across many units • each unit participates in many patterns; no unit represents any one concept • knowledge is stored in weights on connections 14 Memory (2) 15 Parallel Distributed Processing Models • Models start out not knowing anything – weights on connections are random. • Weights are adjusted during learning so input pattern becomes more likely to cause activation of appropriate output pattern • One set of weights works for all concepts • PDP models are very good at handling problems in which multiple constraints have to be satisfied at the same time Memory (2) 16 READ What are the last two letters in this stimulus? SHOO Memory (2) 17 3. Type of Processing Memory (2) Types of Processing In early 70’s, cognitive psychologists began to be • less interested in structural questions (e.g., what is the capacity of STM?) • more interested in process questions (e.g., what is the best way to encode information for later retrieval?). 18 Memory (2) Types of Processing Rehearsal • Maintenance rehearsal • Simple repetition of stimulus • Elaborative rehearsal • Drawing connections between stimulus and what you already know 19 Memory (2) Types of Processing Levels of Processing (Craik & Lockhart) • processing types vary on a depth dimension • semantic processing is deep; form processing (e.g., colour, shape) is shallow • deeper processing facilitates retrieval • Bransford: what matters is match between codes generated at encoding and type of retrieval cues 20 Memory (2) Problems with levels of processing theory: Baddeley has argued that LoP theory • is circular • is an empirical failure under some conditions (doesn’t work with recognition) • Still,it is a useful heuristic: How you encode matters 21 Memory (2) How you encode matters • Deeper processing requires elaboration • Elaboration builds connections between new information and old • Elaboration makes new information more distinctive • But how you retrieve also matters… 22 Memory (2) How you retrieve matters, too: • Tulving and encoding specificity • Recognition vs. Recall • Bartlett and reconstruction • Relearning 23 Memory (2) Tulving’s encoding specificity idea: • Remembering is best when conditions at retrieval match conditions at learning • paired-associates • type of code generated • mental and physical state • context (e.g., Smith, 1986; Godden & Baddeley, 1975) 24 Memory (2) Recognition vs. Recall Recall • retrieve learned materials with no further cues Recognition • identify learned materials when presented or distinguish learned from unlearned 25 Memory (2) Reconstruction • originally suggested by Bartlett (1932) • remembering involves computing ‘what must have happened,’ on basis of: Some encoded material Some knowledge of the world at concept, proposition, and script levels. 26 Memory (2) 27 Relearning First observed by Ebbinghaus (1885) • When you re-learn some material, you acquire it faster than when you learned it the first time • Reduction in effort or time required = savings • Holds even over very long intervals (years) • Very sensitive measure of memory Memory (2) 28 Implications for instruction: Encourage deeper processing Encourage elaboration Encourage use of mnemonics and other strategies Reconstruction is going to happen – don’t try to resist, try to guide it Memory (2) 29 Implications for instruction Make information retrieval more effective by • Matching encoding and retrieval conditions This includes context and student’s state • Providing relevant cues at retrieval • Using prior knowledge to reconstruct missing information Memory (2) Title 30