Learning Objectives for Lecture 12

  • Name the Gestalt principles for grouping objects and patterns.
    similarity, good continuation, proximity
  • Define pop-out.
  • Describe the relationship between distractors and pop-out detection and pop-out reaction times.
  • Principle: pop-out is harder if target and background distractors are highly similar
  • Increased distractor density reduces contour pop-out (Kovacs).
  • Increased density of colinear elements in pop-out contour increases pop-out (Gilbert).
  • Increased density of co-linear elements in pop-out is same as decreasing distance between colinear elements in pop-out.
  • Describe Li and Gilberts model of how cortical connections.
  • Explain why elements inside the contour must be <= 1.6 degrees visual angle before pop-out occurs.
  • Describe developmental time-course for contour pop-out detection
  • Describe contour pop-out detection in adults with untreated amblyopia.
  • Explain Kovac's theory for why normal 5 year olds and untreated amblyopes
    can not see contour pop-out easily
  • Read This Summary of Columnar Organization
  • Extra Credit: Come up with 5 questions from the above Article on Columnar organization. Write out the questions then write out the answers and then reference the page and paragraph number used to make up the question.
  • Weblog for Topics

    • Read Chapter 5 Goldstein Plot your psychophysics curve for contour pop-out
  • Psychophysics Curve Instructions

    • Topic: Theories of Object Perception

    Key Scientists & Psychologists
    Wertheimer
    Treisman
    Marr
    Julesz
    Kovacs
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    source: http://www.niehs.nih.gov/kids/prapples.htm

    Gestalt Theories of Object Perception

    Circles below group by similarity principle.



    Electric cord parts group by contrast similarity
    and good continuation principles.




    Nearly co-linear neighboring gabor patches group by proximity,
    similarity (orientation and contrast) and good continuation principles.


    1) Perception of the whole object not equal to sum of parts.

  • "Pre-attentive" percept of two whole Mona Lisa's.
  • close inspection reveals differences in parts.


    • 2) Perception of the whole object not equal to sum of parts.

  • Left) Four unaligned "packmen" shapes: no contour illusion.
  • Right) Four aligned "packmen" shapes: Kanizsa contour illusion.


    • Principle of good continuation can fail.


    Theories of Visual Search & Feature Pop-out

    1) Pre-attentive versus attentive visual search.

  • High similarity between target and distractor: longer reaction time for visual search.


  • (Fig. 5.34) Target letter "0" pops-out

  • (Fig. 5.35) Target letter "R" hidden

    • Treisman's Study:.
  • (a) Reaction times do not increase with increased distractor number if there is pop-out.

  • (b) Reaction times do increase with increased distractor number if there is no pop-out.

    • Treisman's Theory:.
  • Short reaction times with visual pop-out suggests
    pop out is pre-attentive.

    • Theories of Visual Search & Feature Pop-out

  • Can you see hidden contour?



  • Effects of distractor density on contour detection (in pop-out displays).

  • V1 Neural Connection Model: for optimizing stimulus to percieve pop-out displays.

  • Effects of distractor density on pop-out thresholds.

  • Contour pop-out thresholds in amblyopia and strabismus.

    • weblog

  • Weblog

    • Topic Zar: Heather Read
    heather.read@phy.ucsf.edu
    Back to the homepage URL: http://keck.ucsf.edu/~blondie/PSYCH254