1 / 31

What rules are used to group objects?

What rules are used to group objects?. Definitions (Feature Lists) Family Resemblance Similarity to Prototypes Exemplar models. Definitions and Features. Dogs are animals that have four legs, have fur, bark, wag their tails…. Family Resemblance.

saima
Download Presentation

What rules are used to group objects?

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. What rules are used to group objects? • Definitions (Feature Lists) • Family Resemblance • Similarity to Prototypes • Exemplar models HKU

  2. HKU

  3. HKU

  4. Definitions and Features • Dogs are animals that have four legs, have fur, bark, wag their tails… HKU

  5. Family Resemblance • Ludwig Wittgenstein (1953) proposed that games could not be defined or categorized by features. • Rather, any game shares some resemblance to some (but not all) other games. HKU

  6. Similarity to Prototypes • Rosch (1978). Prototype is a central, average, representation (real or constructed) of a category. • Tokens sufficiently similar to the prototype are considered members of that category. • Memory for specific exemplars. HKU

  7. Exemplar Models • To remember a category, just remember all the members of the category. • Head-filling-up problem. • Evidence for abstractions. HKU

  8. Perception Top-down Or Bottom-up? HKU

  9. The problem of perception • How does our perceptual system arrive at a “best” representation of the world? • Conflicting demands: • Accuracy • Efficiency HKU

  10. Data-driven processing(bottom-up) HKU

  11. Standard (naïve) assumption is that perception is entirely data-driven • Why is this naïve? • Perception must be accomplished in sub-optimal conditions • Need for speed • Need for computational efficiency • But also need for accuracy! • A common solution: “Best guess” HKU

  12. Concealed and bi-stable figures: Evidence for a role of knowledge in perception HKU

  13. Changes conscious processing (interpretation, object recognition) Changes unconscious processes (patterns of eye movements) Application of knowledge changes the way concealed and bi-stable figures are perceived HKU

  14. HKU

  15. HKU

  16. Application of Knowledge • Can be automatic • Either innately, or once learned • Can also be controlled HKU

  17. Rabbit/Duck Jastrow (1900) HKU

  18. Impossible Trident HKU

  19. Illusions: Obligatory application of knowledge in contradiction to available data. HKU

  20. Application of knowledge is obligatory in these illusions HKU

  21. Sources of Illusions • Illusions arise because our perceptual system is structured to act as if certain assumptions about the world are true. • We can construct situations in which those assumptions appear to be true, but in fact are not. These situations are called illusions. HKU

  22. Sources of Illusions • Knowledge of visual cues to distance • The Müller Lyer Illusion • Filling in missing information • Object occlusion • Using context • Circles of relative size • Text tricks • Shades of white • Circularity in pitch perception HKU

  23. Which vertical line is longer? Neither! They are the same length! The Müller-Lyer Illusion Müller-Lyer (1889) HKU

  24. Explanation • We need to be able to adjust our knowledge of an object’s size based on our perception of how far away from us it is. • The arms of the arrows make the vertical lines look like the edges of corners – one pointing toward us, one pointing away. • That makes it appear as if the vertex of the corner (the vertical line) is a different distance from us in each figure. HKU

  25. What triangle? HKU

  26. Explanation • Most things in the world do not have abrupt, regular discontinuities. • It makes more sense to assume that the black spots are circles rather than Pac Men. • It also makes sense, then, to assume that the 3 “bites” are caused by the same object which lies in front of the circles. • “Makes sense” means is more likely to be a correct representation of the world. HKU

  27. Contextual cues Which of the two middle circles is smaller? HKU

  28. Is this a letter or a number? HKU

  29. Circularity in pitch perception PC/.wav Mac/AIFF Waterfall (M. C. Escher) HKU

  30. Bibliography • Sheperd, R. N. (1964). Circularity in judgements of relative pitch. Journal of the Acoustical Society of America, 36, 2346-2353. • Rosch, E. (1978). Principles of categorization. In Rosch, E. & Lloyd, B. (Eds.) Cognition and Categorization. Hillsdale, NJ, Lawrence Erlbaum Associates. • Wittgenstein, L. (1953). Philosophical Investigations. New York, Macmillan. • Note: The illusions used in this demonstration come from various sources. When the original source is identifiable, it is given above. Otherwise, as much information as possible is provided to identify the illusion’s original author. Many illusions are so widely distributed that they appear to be in the public domain. The following texts and other sources are recommended: • Deutsch, D. (1975). Musical Illusions. Scientific American, 233(4), 92-104. • Ernst, B. (1976). The Magic Mirror of M. C. Escher. New York, Ballantine. • Ernst, B. (1992). Optical Illusions. Trans. K. Williams. Originally published as Het Begoochelde Oog. Taschen Verlag. • Held, R. (1974). Image, Object, and Illusion: Readings from Scientific American. Scientific American, Inc. • Houtsma, A. J. M., Rossing, T. D., Wagenaars, W. M. (1987). Auditory Demonstrations (CD). Eindhoven, The Netherlands, Institute for Perception Research (IPO) and the Acoustical Society of America (ASA). HKU

More Related