Affordances

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An overview on Affordances, what they are, how they might be defined.

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Affordances

  1. 1. A Anton Flügge, Hannes Schulz University of Osnabrück, Department of Cognitive Science December 21st 2005
  2. 2. O 1 G   C  A 2 D T  A 3 L D A 4 M. A  A 5 A
  3. 3. O 1 G   C  A 2 D T  A 3 L D A 4 M. A  A 5 A
  4. 4. Gibson’s Concept Types Later Definitions Aspects Application J J G 1904, McConnelsville, OH 1979, Ithaca, NY Ph.D. Psychology, Princeton, 1928 Worked at Cornell University, Ithaca, NY Main contribution: The Perception of the Visual World (1950) Claims perception is direct Invented influential term “Affordance” Founded School of Ecological Psychology 4 / 26
  5. 5. Gibson’s Concept Types Later Definitions Aspects Application E P E P “It’s not what is inside the head that is important, it’s what the head is inside of” Animals stand in a relation to the environment To explain behaviours it is necessary to study the environment in which behaviours take place 5 / 26
  6. 6. Gibson’s Concept Types Later Definitions Aspects Application D P D P Perception is gathering information from meaning-laden environment without performing inferences on the sensations 6 / 26
  7. 7. Gibson’s Concept Types Later Definitions Aspects Application G’ A-D D (A) The affordances of the environment are what it offers the animal, what it provides or furnishes, either for good or ill. The verb to afford is found in the dictionary, but the noun affordance is not. I have made it up. I mean by it something that refers to both, the environment and the animal in a way that no existing term does. Animal Environment Nutrition 7 / 26
  8. 8. O 1 G   C  A 2 D T  A 3 L D A 4 M. A  A 5 A
  9. 9. Gibson’s Concept Types Later Definitions Aspects Application E: B A Nutrition Dying 9 / 26
  10. 10. Gibson’s Concept Types Later Definitions Aspects Application E: P A Drive-on Affordance 10 / 26
  11. 11. Gibson’s Concept Types Later Definitions Aspects Application E: P A Stove-Top-Control 11 / 26
  12. 12. Gibson’s Concept Types Later Definitions Aspects Application E: C A Cognitive Affordances are provided by cultural conventions 12 / 26
  13. 13. Gibson’s Concept Types Later Definitions Aspects Application E: M A Knowledge (Semantic Affordance) Mixed Affordance Ties (Physical Affordance) 13 / 26
  14. 14. O 1 G   C  A 2 D T  A 3 L D A 4 M. A  A 5 A
  15. 15. Gibson’s Concept Types Later Definitions Aspects Application A  B S Warren (1984): Used “affordance” as ratio between size of body-parts and environment 15 / 26
  16. 16. Gibson’s Concept Types Later Definitions Aspects Application D D (D) Tendency to any action or state resulting from natural constitution Dispositions are always actualized if certain circumstances occur 16 / 26
  17. 17. Gibson’s Concept Types Later Definitions Aspects Application T’ (1992) F D (A) p is Affordance ⇔ ∃Wpq : Wpq = j (Xp , Zq ) (1) Environment X Animal Z p Disposition of the p q Environment q Disposition of the Animal X Environment j Z Animal j Juxtaposition Wpq Wpq Entity with (new) r property r 17 / 26
  18. 18. Gibson’s Concept Types Later Definitions Aspects Application S’ (2003) C 1 Affordances should describe what can be done, not what has to be done. 2 In any situation many actions are possible, most aren’t actualized. 3 Dispositions must be actualized in the right circumstances (Turvey’s def), but j filters them: Inconsistent. 4 Based on Turvey the property r cannot be directly perceived, it must be inferred 18 / 26
  19. 19. Gibson’s Concept Types Later Definitions Aspects Application S’ (2003) D D (A) An Affordance r is an emergent property of the animal-environment system Wpa = (Xp , Za ). Environment X Animal Z p a p Disposition of the Environment a Ability of the Animal Emergence X Environment Z Animal Wpa Entity with emergent Wpa property r r 19 / 26
  20. 20. Gibson’s Concept Types Later Definitions Aspects Application C (2003) N U Affordances are relations, not properties of entities Relation TallerThan(Averell, Joe) The relation is not inherent in either of the objects but depends on both of them The relation is not an extra “thing”, yet it exists and is perceivable 20 / 26
  21. 21. Gibson’s Concept Types Later Definitions Aspects Application C’ A D D An Affordance is a relation between a feature f of the environment and an ability a of the animal: Affords-Φ(f , a) Φ Behavior Affords-Φ Environment X Animal Z Relation/Affordance f a f Feature of Environment a Ability of Animal Affords-Φ X Environment Z Animal 21 / 26
  22. 22. O 1 G   C  A 2 D T  A 3 L D A 4 M. A  A 5 A
  23. 23. Gibson’s Concept Types Later Definitions Aspects Application A  E Reed (1996): Affordances are offered by Environment Affordances exist independently of animals Affordances exert selection pressure during evolution Observed complementarity is an epiphenomenon 23 / 26
  24. 24. Gibson’s Concept Types Later Definitions Aspects Application A R  A E According to previous definitions a matching animal must exist for something to be called “affordance”. Analogous to Dennett (1998): Female hippos depend for loveliness on potential observer, suspiciousness needs an actual observer Affordances are “lovely”, not “suspicious”. 24 / 26
  25. 25. Gibson’s Concept Types Later Definitions Aspects Application T M P Indirect View of Perception Direct Perception of Affordances Direct View of Perception Affordances can be a solution to the problem how our minds can be private when we assume perception to be direct. 25 / 26
  26. 26. Gibson’s Concept Types Later Definitions Aspects Application E D (E) An Event is a change in the layout of affordances (Chemero 2000) 26 / 26
  27. 27. Gibson’s Concept Types Later Definitions Aspects Application N D (N) A niche is a set of affordances (Gibson, 1979) Gibson Bruce Environment Housing Nutrition 27 / 26
  28. 28. O 1 G   C  A 2 D T  A 3 L D A 4 M. A  A 5 A
  29. 29. Gibson’s Concept Types Later Definitions Aspects Application A: H C I User interface affordances in a planning representation (Amant 1999) U  A C Affordances are used to determine the costs for execution of operators generation of operators Affordances used to model usability of user interfaces Allows “search” for optimal design in problem space 29 / 26
  30. 30. Gibson’s Concept Types Later Definitions Aspects Application A: S D Affordance Theory for Improving the Rapid Generation, Composability, and Reusability of Synthetic Agents and Objects (Cornwell 2003) I am attackable U  A C Objects in Env’t tell agents what they are useful for Easy adding of new agents Enhanced reusablitiy 30 / 26
  31. 31. Gibson’s Concept Types Later Definitions Aspects Application S “Affordance” is a term Even without a consensous invented by James J. Gibson various fields of research have been stimulated The concept is intuitively appealing There is an ongoing debate about a formal definition 31 / 26

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