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Organizational Notes

Organizational Notes. no study guide no review session not sufficient to just read book and glance at lecture material midterm/final is considered hard by some students questions will relate to both book and lecture material . What is Cognitive Science?.

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Organizational Notes

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  1. Organizational Notes • no study guide • no review session • not sufficient to just read book and glance at lecture material • midterm/final is considered hard by some students • questions will relate to both book and lecture material

  2. What is Cognitive Science? … is the interdisciplinary study of mind and intelligence, embracing philosophy, psychology, artificial intelligence, neuroscience, linguistics, and anthropology (Stanford Encyclopedia of Philosophy) http://plato.stanford.edu/entries/cognitive-science/

  3. Practical Value • Education: • Intelligent tutoring systems • Automatically grading exams • Legal: • Distinguishing between true and false memories • Evaluating line-ups • Sales • Understanding beliefs and desires • Information technology: • Search engines • Building intelligent systems Cognitive scientists might have some things to say about these issues.

  4. Most cognitive scientists are cognitive psychologists, computer scientists, or cognitive neuroscientists (from: Schunn et al. 2005)

  5. Understanding Computation Building computer models that learn from the environment To understand how Computer Science/ the brain works Artificial I ntelligence Neuroscience Interdisciplinary study of intelligent behavior To understand For behavioral data in Cognitive limits of theories various tasks; mental representations and processes Science Philosophy Cognitive Psychology To understand Linguistics structure of language We will focus mostly on insights from Cognitive Psychology

  6. Areas of Study • Cognitive psychology/science is about studying internal processes that are often unobservable, e.g.: Perception, Attention, Memory, Visual Imagery, Language, Concept Learning, Reasoning • Need converging evidence from different perspectives to really understand cognitive processes ?

  7. Levels of Analysis • Implementational: • Where does mental activity take place in the brain? • How is processing actually done with neural activity? • Algorithmic: • What is the abstract representation for input and output? • What stages are used to process information? • (also known as information processing level) • Computational: • Why does the algorithm work well? • What is the goal or purpose of the computation? (Marr, 1982)

  8. Levels of Analysis Example

  9. Cognitive Neuroscience • the study of the relation between cognitive processes and brain activities • Potential to measure some “hidden” processes that are part of cognitive theories (e.g. memory activation, attention, “insight”) • Measuring when and where activity is happening. Different techniques have different strengths: tradeoff between spatial and temporal resolution

  10. Information Processing • Information processing models resemble processing in computers – made cognitive psychology popular • Idea is that information is processed in a number of stages • The major goal of information processing research is to • identify those processes • identify how information is represented

  11. Types of Processing • Bottom-up processing • Top-down processing • Parallel processing • Serial processing

  12. An early version of the information-processing approach purely bottom up or stimulus-driven

  13. A Demonstration of Top-Down Processing

  14. Top-down processing: perception affected by knowledge of world Why do we seem to have a fairly robust interpretation of which shapes are concave and convex when the perceptual information is perfectly ambiguous? -> perception affected by knowledge (Kleffner & Ramachandran, ’92)

  15. First time, sine wave speech sounds incomprehensible (to most) After hearing the natural utterance, perception of sine-wave speech seems to be quite different Top down processing: perception affected by memory http://psiexp.ss.uci.edu/research/teachingP140C/demos/sinewavespeech.aif "The steady drip is worse than a drenching rain." http://psiexp.ss.uci.edu/research/teachingP140C/demos/naturalutterance.aif (for more info: http://www.haskins.yale.edu/haskins/MISC/SWS/SWS.html)

  16. Sound Induced Illusory Flashes • Example of parallel and interactive processing: • processing of perceptual information in one modality is often affected by processing in another modality • Demo of sound induced illusory flashes: • http://shamslab.psych.ucla.edu/demos/ • http://www.cns.atr.jp/~kmtn/soundInducedIllusoryFlash/index.html • http://www.cns.atr.jp/~kmtn/soundInducedIllusoryFlash2/ • For more information on this effect see: http://shamslab.psych.ucla.edu/publications/SCR-reprint.pdf • note: demo might not work on your particular computer • Demo shows that visual perception affected by auditory perception

  17. Top-down processingLater stages of processing affect earlier stages can explain effects of Knowledge, memory, expectations and context

  18. Parallel vs. Serial Processing • To illustrate the difficulty of distinguishing between serial and parallel processing, consider the Sternberg task • Goal: what steps are involved in comparing information to memory? How long do these steps take? • Task: • give subjects memory sets. E.g. 3 9 7 • Probe memory with targets and foil digits: 9 = “yes”, 6=“no”. Measure reaction time. • Vary the size of these memory sets

  19. Typical Sternberg Results • Plot reaction time as function of memory set size and type of trial (targets/foils) • What are the implications of seeing a linear increase in reaction time as a function of memory set?

  20. A serial information processing model for Sternberg task Make Decision Is it a 7? Perceive Stimulus Is it a 3? Is it a 9? yes 9 This serial information processing model predicts a linear increase

  21. A parallel information processing model for Sternberg task Is it a 3? Perceive Stimulus 9 Make Decision Is it a 9? yes Is it a 7? This parallel information processing model also predicts a linear increase

  22. Identifiability • Sometimes, behavioral results do not allow processes and representations to be uniquely identified (e.g. Sternberg task) • Identifiabilityrefers to the ability to specify the correct combination of representations and processes used to accomplish a task

  23. How can we tell models/theories apart? • Need converging evidence to tell theories apart • More behavioral data • Data from cognitive neuroscience • Data from neuropsychology

  24. Note • Please read book • to review major brain structures and their functions • to review brain imaging techniques • See also additional PowerPoint slides available on class website • cogneuro review slides

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