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Activity (2 pts) 1. One main claim from Pinker reading that you found provocative / insightful / useful. 2. One main claim from Pinker reading that you found confusing / problematic. X What is Cognitive Psychology? Computational Theory of Mind Five Key Features: 1. 2. 3. 4. 5. Posits a level of analysis wholly separate from the biological or neurological Faith that central to any understanding of the human mind is the computer Deliberate decision to de-emphasize certain factors that may be important but complicate things (emotion, history/culture, role of context) Faith in interdisciplinary studies (philosophy, psychology, artificial intelligence, linguistics, anthropology, neuroscience) Claim that a key ingredient in contemporary cognitive psych. is the agenda of issues which have long exercised epistemologists in the Western philosophical tradition Computational Theory of Mind & Memory Despite huge variation in human capacities, we all come equipped with same info-processing system Outline of Today’s Lecture Review fundamental aspects of human computational system Contrast humans & computers (what makes humans unique?) Connectionist models (briefly) Initial Reception of Info. Information, in form of physical energy (light, sound, pressure etc) is received by receptors to particular energy forms (e.g. rods & cones) Receptors send signals in form of electrochemical impulses to brain Thus, the first transformation of information: multiple forms of energy (light, sound, pressure, etc) one common form Nerve impulse goes to central nervous system, where it is registered in immediate memory different immediate memories for different senses: iconic, echoic Immediate memory holds a fairly complete representation of incoming sensory information for extremely brief period of time Selective Perception Selective Attention: Focusing on what is most important in a stimulus array Biological tendency (thanks to evolution) = sudden loud noises, motion, light/dark contrast Expertise in a domain = ability to attend to the most important parts of a stimulus (e.g. chess) The pattern knowledge we acquire over a lifetime increases the accuracy of selective perception of items in familiar contexts Perception is influenced by: 1. 2. Prior knowledge Context of the stimulus itself Perception is as much a “top-down” process as it is a “bottom-up” process Working Memory Working Memory: Awareness (what you are aware of at any given moment is said to be in your WM) Information stored here decays within ~ 10 seconds unless rehearsed (e.g. telephone #) WM holds 7 2 units of information (Miller, 1956), hence it is the ‘bottleneck’ of info.processing WM functions as a mental workspace (like a scratchpad of sorts) Because of limited capacity, it’s difficult to perform several (cognitively demanding) tasks as once One way around the limitations of WM is “automating” tasks (e.g., decoding text) Automatic processes: processes performed without much awareness Controlled processes: processes that require a lot attention Storage & Long-Term Memory Information in working memory can be stored in longterm memory (LTM) Storage: a set of processes by which new information is integrated in various ways with known information Function of LTM: store information for later use LTM: long duration (perhaps even a lifetime) inability to remember is more a failure of finding a good retrieval cue than loss of information Exercise: Name people in your high-school graduating class x Common results: recall difficult until good retrieval cues found, such as… thinking systematically about subgroups of students o o o “kids in my neighborhood” “kids in my chemistry class” “kids who beat me up” We stopped here & will continue with the rest tomorrow. Retrieval Retrieval: a set of processes that put information stored in LTM into a state in which it can be used for current processing Different for controlled & automatic processing… Controlled processing LTM WM Retrieval means becoming aware of the stored info. activation: Process of re-establishing awareness of it e.g. when students recall facts for a test Automatic processing LTM effectors Retrieval by pattern-matching processes e.g. 26 x 32 x guide for the sequence of steps you take is automatically retrieved when you recognize the familiar pattern of numbers & multiplication sign (contra, ex. Mult.tables) Response Generation & Effectors When we wish to respond to a stimulus, the response has to be sequenced in some way e.g., physical responses, language Response Generation: activities that organize the sequence of responses and send messages for the appropriate effectors to execute the sequence Effectors: Muscles Glands Arms hands voice apparatus, etc. Control Processes Flow of information in the human system is generally organized around achieving some purpose In other words, mental computations are not random Control Processes: the processes that guide and monitor information-processing events. Goal setting Planning how to achieve goals Monitoring goal attainment Revising plans When we consciously use such processes, we are said to be using metacognitive processes (‘meta’ = ‘above’) In contrast to metacognitive processes… some control processes, either innately or through learning, are deployed automatically. Not metacognitive because not ‘above’ the processing event but rather part of it In learned, automated skills, the flow of control is embedded in the skill (e.g., sequence as a control structure) Computational Theory of Mind & Memory Despite huge variation in human capacities, we all come equipped with same info-processing system Outline of Today’s Lecture Review fundamental aspects of human computational system Contrast humans & computers (what makes humans unique?) Connectionist models (briefly) Humans vs. Computers Similarities Human Computer Input device senses keyboard central processing unit working memory CPU long-term storage medium LTM disk output device effectors paper/screen Human Computer size of WM/CPU 5 bits 800,000,000 bits size of LTM 1,000,000,000 bits* unlimited speed of access w/in WM .025 sec .000000015 sec speed of access to LTM .200 sec .020 sec Differences Humans vs. Computers Human Computer preferred storage mode analog; time-oriented digital; list oriented retention of information graded all-or-none efficiency (bits/sec) low high capacity dependent on experience independent of experience very dependent dependent independent independent retrieval: * relative to context * relative to previous retrievals interconnectedness general purpose; purpose of information inopen set of functions human memory special or general purpose; closed set of functions Human vs. Computers Human dependency on context allows for learning & adaptation to take place Our tendency for partial memory allows us to think of novel solutions to problems Thus, the human information processing system has evolved to be adaptive Computational Theory of Mind & Memory Despite huge variation in human capacities, we all come equipped with same info-processing system Outline of Today’s Lecture Review fundamental aspects of human computational system Contrast humans & computers (what makes humans unique?) Connectionist models (briefly) Connectionism How is the mind instantiated in the brain? We have detailed neural models of low level cognition (e.g. how we perceive a line) We have NO specified neural models of more advanced cognitive processes (e.g., how we remember facts about people or judge their character) Traditionally, the more advanced aspects of human cognition have only been discussed in terms of abstract information processing models EXCEPT… Recent efforts to develop models of higher-level processes that are better grounded in our understanding of neural processing Start with general knowledge of how neurons work Ask the Q: how could higher-level function be achieved by connecting together basic elements like neurons Connectionism Connectionism Connectionism: Theory and research concerned with ways of connecting neural elements together to account for higher-level cognition Example: McClelland & Rummelhart’s PDP model PDP = parallel distributed processing models how neural elements are interconnected & simultaneously interact with each other X How many can you remember? 39583129553468401548 Activity (3 pts) Read 'Thanks for the Memories' What import might this have for a teacher in a classroom? (One paragraph) X