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Introducing Perception

Introducing Perception. Of microbes and men. O rganisms from microbes to man must interact with the world F ind food and mates, avoid predators and physical harm. Representing the world.

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Introducing Perception

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  1. Introducing Perception PSY 295 - Fall 2012 - Grinnell College

  2. Of microbes and men • Organisms from microbes to man must interact with the world • Find food and mates, avoid predators and physical harm PSY 295 - Fall 2012 - Grinnell College

  3. Representing the world • Organisms extract information about the environment tobuild an internal representation of the environment • Representations guide their actions from Russel & Norvig (1995) PSY 295 - Fall 2012 - Grinnell College

  4. Sources of useful information • Reflected light • Pressure/temperature • Sound waves • Chemical gradients PSY 295 - Fall 2012 - Grinnell College

  5. Representations • Sensory representations need not be sophisticated to be useful • Even single cell organisms respond to sensory cues PSY 295 - Fall 2012 - Grinnell College

  6. Euglena • Single cell photo-synthetic organism • Has eyespot which is sensitive to light • Moves towards light – Phototaxis PSY 295 - Fall 2012 - Grinnell College

  7. Bacteria • Swim towards food and away from poisons • Chemotaxis PSY 295 - Fall 2012 - Grinnell College

  8. Nervous systems • Sensation and action in single-cell organisms are mediated by biochemical pathways • In multicellular organisms, sensation and action are mediated by the nervous system PSY 295 - Fall 2012 - Grinnell College

  9. The neuron • Nervous systems are comprised of neurons • Neurons are cells specialized for transmitting information PSY 295 - Fall 2012 - Grinnell College

  10. Neural networks • To perform complicated information-processing, neurons are arranged into neural networks PSY 295 - Fall 2012 - Grinnell College

  11. Sensation and Action • World-representing only useful if the organism can move • Organisms that cannot move do not need nervous systems PSY 295 - Fall 2012 - Grinnell College

  12. Tunicates • Larval form is like a tadpole which swims around • Once it finds a suitable rock, it cements itself in place and proceeds to digest its own brain PSY 295 - Fall 2012 - Grinnell College

  13. Sensory-motor transformations • A simple example of sensation leading to action is a reflex PSY 295 - Fall 2012 - Grinnell College

  14. Interneurons • More sophisticated sensory-motor transformations require an intervening hidden layer of interneurons PSY 295 - Fall 2012 - Grinnell College

  15. Bending reflex in leech from Churchland & Sejnowski 1992 PSY 295 - Fall 2012 - Grinnell College

  16. Leech reflex circuit from Churchland & Sejnowski 1992 PSY 295 - Fall 2012 - Grinnell College

  17. Far Side Cartoon “Stimulus, response, stimulus, response. Don’t you ever think?” PSY 295 - Fall 2012 - Grinnell College

  18. More sophisticated representation • Building more accurate representations of the world like we do can provide great advantages • Remember, reason about, and simulate the world PSY 295 - Fall 2012 - Grinnell College

  19. Sources of useful information • Reflected light • Pressure/temperature • Sound waves • Chemical gradients PSY 295 - Fall 2012 - Grinnell College

  20. Light • Provides information about things far away from the organism • Organisms living in caves or in deep sea often lack eyes Texas blind salamander PSY 295 - Fall 2012 - Grinnell College

  21. Evolution of eyes • Eyespots are simplest ‘eyes’ • Cup eyes give directionality from Land & Ferdnald 1992 PSY 295 - Fall 2012 - Grinnell College

  22. Evolution of eyes • Pinhole opening helps to focus light • Reduces amount of light entering eye from Land & Ferdnald 1992 from Palmer 1999 PSY 295 - Fall 2012 - Grinnell College

  23. Evolution of eyes • A lens focuses the image while permitting lots of light into eye from Palmer 1999 from Land & Ferdnald 1992 PSY 295 - Fall 2012 - Grinnell College

  24. Visual system • A sophisticated eye and visual system permits detailed analysis and interpretation of the scene from Hubel (1995) PSY 295 - Fall 2012 - Grinnell College

  25. This course • We will study information processing and perception in mammalian sensory systems • Touch, vision, hearing, olfaction, taste • Strong emphasis on sensory neuroscience • Connections to machine vision, medicine and consciousness PSY 295 - Fall 2012 - Grinnell College

  26. Related courses • Fall 2012 • Machine Vision (CS-295-02) • Vision Science Seminar (NRS-495) • Physiological Psychology (PSY-246) • Spring 2013 • Computational Neuroscience (PSY-395) PSY 295 - Fall 2012 - Grinnell College

  27. See you later! PSY 295 - Fall 2012 - Grinnell College

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