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Development of Perceptual Organization

Development of Perceptual Organization. Ruth Kimchi University of Haifa. Leuven, Belgium 2014. Perceptual Organization. The processes structuring the bits and pieces of visual information into coherent units that eventually we experience as environmental objects. Gestalt Psychology.

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Development of Perceptual Organization

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  1. Development of Perceptual Organization Ruth Kimchi University of Haifa Leuven, Belgium 2014

  2. Perceptual Organization The processes structuring the bits and pieces of visual information into coherent units that eventually we experience as environmental objects

  3. Gestalt Psychology • Organization is achieved by innate grouping and segregation principles • Grouping • Classical: proximity, good continuation, similarity, common fate, closure (Wertheimer, 1923/1955) • New: common region (Palmer, 1992); connectedness (Palmer & Rock, 1994) • Figure-ground segregation • Classical: relative size, contrast, convexity, symmetry(Rubin,1915/1958) • New: familiarity (Peterson & Gibson, 1994), lower region (Vecera et al., 2002), spatial frequency (Klymenko& Weisstein, 1986), top/bottom polarity (base width; Hulleman & Humphreys, 2004), extremaledges (Palmer &Ghose, 2008)

  4. Modern theories of visual perception have treated PO as: • Aunitary phenomenon • Operates at a single, early, preattentivestage • In a bottom-up fashion • Provides the substrate on which higher-level perceptual processes operate (e.g., Julesz, 1981; Marr, 1982; Neisser, 1967; Treisman, 1982, 1988).

  5. PO:Not a monolithic entity but a multiplicity of processes (Behrmann & Kimchi, 2003; Kimchi, 2003) • Time course (e.g.,Han et al., 2002; Hadad & Kimchi, 2008; Kurylo, 1997; Kimchi, 1998, 2000; 2012; Razpurker-Apfeld& Kimchi, 2007) • Developmental trajectory (e.g., Hadad & Kimchi, 2006; Hadad et al., 2010; Hayden et al., 2009; Kimchi, 2012; Kimchi et al., 2005; Kovacs, 2000; Scherfet al., 2009; Quinn & Bhatt, 2006) • Multifaceted relationship with attention (e.g., Ben Av & Sagi, 1995; Freeman et al., 2001; Kimchi & Razpurker-Apfeld, 2004; Kimchi & Peterson, 2008; Kimchi et al., 2007; Moore et al., 2003; Russell & Driver, 2005; Shomstein et al., 2010 ) • Influenced by experience and familiarity (e.g., Kimchi & Hadad, 2002; Peterson & Gibson, 1994; Vickery & Jiang, 2009; Zemel et al., 2002)

  6. Ontogenesis of Perceptual Organization: Theoretical Approaches • Gestalt (Koffka, 1935; Kohler, 1929; Wertheimer, 1923/1958): • most, if not all, of the basic organizational processes operate from birth. • Hebb (1949): • perceptual organization is a learned process in which eye movements that are used to scan images generate the internal representation of objects. • Contemporary (e.g., Baillargeonet al. 2009; Bhatt & Quinn, 2011; Johnson, 2009; Spelke, 1982): • A combination of innate and learning contributions.

  7. Ontogenesis of Perceptual Organization • Functional onset • Rate of development • The age at which ultimate functioning is attained

  8. Infants Research: • 3-month-olds are capable of grouping visual elements into unitary structures in accord with both classical and modern organizational principles: • Common motion (Kellman et al., 1987; Kellman & Spelke, 1983; Kellman et al., 1986) • Good continuation (Quinn & Bhatt, 2005a) • Proximity (Quinn et al., 2008) • Connectedness (Hayden et al., 2006) • Common region (Bhatt et al., 2007) • Lightness similarity (Quinn, et al., 1993) even newborns (Farroni et al., 2000), and 2-month-olds(Farran et al., 2008).

  9. Sensitivity to global and local structures • 3- to 4-month-olds sensitive to both structures, with a greater sensitivity to global (Freeseman, et al., 1993; Frick, et al., 2000; Ghim & Eimas, 1988; Quinn, et al., 1993; Quinn & Eimas, 1986) • The ability to perceive the unity of partly occluded objects • emerges at 2 months. • Sensitivity to subjective contours • 3- to 4 months. These completion abilities continue to develop during the first year of life(e.g., Craton, 1996; Csibra, 2001; Eizenman & Bertenthal, 1998; Ghim, 1990; Johnson & Aslin, 1995, 1996; Kavsek, 2002)

  10. Some organizational principles have a later functional onset than other • 3-month-olds are insensitive to closure (Gerhardstein et al, 2004) • Grouping by form similarity only in 6- to 7-month-olds (Quinn & Bhatt, 2006)

  11. Grouping by shape similarity 6- to 7-month-olds, but not 3- to 4-month olds (Quinn et al. 2002) 3- to 4-month-olds can use form similarity to organize elements if they are provided with varied examples with which to abstract the invariant arrangement of the pattern (Quinn and Bhatt, 2005).

  12. Studies beyond the 1-2 years: • Protracted developmental trajectory for some perceptual organization abilities, even those that appear to emerge during infancy: • Visual spatial integration (e.g., Hadad & Kimchi, 2006; Hadad et al., 2010; Kaldy & Kovacs, 2003; Kovacs, 2000; Kovacs et al., 1999) • Subjective contours(e.g., Abravanel ,1982; Hadad et al., 2010) • Grouping multiple elements into a global shape(Burack et al., 2000; Enns et al., 2000; Kimchi et al., 2005; Mondloch et al., 2003; Scherf et al., 2009)

  13. Although many perceptual organization abilities emerge early in life, organizational abilities vary in their rate of development and some reach the ultimate level of functioning only in late childhood or even in adolescence.

  14. Two series of studies: • Grouping and individuation of multiple elements in the organization of hierarchical stimuli • Grouping of shape by perceptual closure

  15. Development of the Perceptual Organization of Hierarchical Stimuli • Infants studies: Greater sensitivity to global than to local structures(e.g., Ghim & Eimas, 1988). • Sensitivity to the global structure in hierarchical visual stimuli continues to develop into late childhood (Burack et al., 2000; Enns et al., 2000; Harrison & Stiles, 2009; Porporino et al., 2004; Scherf et al., 2009). • Longer developmental progression for processing local structure (Mondlochet al., 2003).

  16. Development of the Perceptual Organization of Hierarchical Stimuli • Performance of 5- 10- and 14-year-olds and young adults on few- and many-element hierarchical displays, was compared in two tasks: * Visual search *Speeded classification

  17. Visual Search • Task: search for a diamond target among square distractors. • Display size: 2, 6, or 10. • Dependent variables: • Baseline RT (display size=2; measures response speed independent of search rate). • Search rate - The slop of the RT function over display size. Kimchi et al., 2005

  18. Results Accuracy: 5-year olds: 96% 10-year olds: 98% 14-year olds: 97% Adults: 94%

  19. Baseline RT (Display Size = 2, Target-present Trials) • RT improved with age. • Global advantage in the many-element stimuli. • No age related changesin target-distractor discriminability. Kimchi et al., 2005

  20. RT Slopes (Target-present Trials) • Few-element: Search rates for global target improved with age; the efficient search for local target did not vary with age. • Many-element: Search rates for local target improved with age; the efficient search for global target did not vary with age. • Significant improvement between 5 to 10. Kimchi et al., 2005

  21. Speeded Classification • Classify the central stimuli with the stimuli to the right or left side: • global classification: based on similarity in global configuration • local classification:based on similarity in local elements

  22. Few-element:Accuracy of global classification improved with age; no age related changes for local classification. • Many-element: Accuracy of local classification improved with age; no age related changes for global classification. • Significant improvement between age 5 – 10.

  23. Summary of Results • Search rates for global targets and accuracy of global classification • improved with age for the few-element patterns • did not change with age for the many-element patterns. • Search rates for local targets and accuracy of local classification • improved with age for the many-element patterns • no age-related changes for the few-element patterns. • Improvement mainly for the transition from ages 5 to 10.

  24. Longer developmental progression for grouping a few large elements than many small elements • Longer developmental progression for individuating many small elements than few large elements.

  25. How processing might change developmentally to produce this pattern of results? • Individuating elements within many-element patterns requires attentional change (e.g., narrowing the spatial focus or refocusing on a different detail level). • The ability to flexibly deploy attention improves with age (e.g., Enns & Girgus, 1985; Plude, Enns, & Brodeur, 1994). • The organization of the individuated few large elements into a global configuration requires apprehending the spatial relations among them. • spatial abilities improves with age (e.g., Stiles, 2001).

  26. Local Target Global Target Congruent Incongruent • Enns et al. (2000) used few-element hierarchical stimuli, and therefore concluded that grouping develops with age. • Mondloch et al. (2003) used many-element stimuli, and therefore concluded that local processing develops with age.

  27. In contrast to the early maturation of grouping many small elements • Scherfet al. (2009), using primed matching, showed age-related improvement in the ability to encode the global shape of the many-element patterns at the short prime durations, which continued through adolescence. • Clear early advantage for encoding the global shape was observed only in adults; children were biased to encode the local elements, and adolescents began to demonstrate the beginning of early global advantage.

  28. Scherf, Behrmann, Kimchi, & Luna, 2009

  29. Different tasks may require different representations for successful performance, crude versus more refined, which depend on relatively rudimentary ability to group elements into a shape versus more mature ability, respectively.

  30. A coarse representation of the global configuration may suffice to support performance in visual search and speeded classification tasks (Kimchi et al., 2005). • Primed matching task (Scherf et al., 2009) requires a more precise, integrated representation of the global shape of the prime for facilitating responses to test figures similar to the prime in the global shape and/or interfering with responses to the test figures dissimilar in global shape to the prime.

  31. Summary • Children and adolescents are capable of grouping many small elements to a certain degree, which may support some global information and figural perception, but the full process of integrating local elements into coherent shapes to the extent of facilitating shape identification appears to develop late into adolescence. • This long developmental trajectory coincides with what is known about the structural and functional development of the ventral visual pathway (Bachevalier, Hagger, & Mishkin, 1991; Gogtay et al., 2004).

  32. Grouping of Shape by Closure

  33. The Role of Closure in Perceptual Organization The Gestalt psychologists noted that perceptual closure plays a crucial role in perceptual organization, in particular, in determining the shape of an object: “If a line forms a closed, or almost closed, figure, we see no longermerely a line on a homogeneous background, but a surface figure bounded by the line”(Koffka, 1935).

  34. Several psychophysical studies with adults documented the role of closure in perceptual organization (e.g., Elder & Zucker, 1993, 1994, 1998, Hadad & Kimchi, 2008; Kimchi, 2000; Kovacs & Julesz, 1993; Saarinen& Levi, 1999). • Greater contour detection sensitivity for closed fragmented contours than for open contours (Kovacs & Juleasz, 1993). • Shape discrimination is more precise for closed contours than for non-closed contours (Saarinen & Levi, 1999). • Search for a concave target among convex distractors is efficient for closed stimuli but inefficient for open stimuli (Elder & Zucker, 1993).

  35. In natural scenes, closed connected contours often appear in the image as fragmented, due, for example, to occlusion. • The perceptual system must group the image fragments and uncover the shape of the object

  36. Research with adults: The efficiency of the grouping depends on • The size of the gaps between the closure-inducing fragments(Elder & Zucker, 1993), and on • The distribution of the gaps along the contour -- whether the gaps occur at points of change in contour direction or at straight contour segments (Kimchi, 2000; Spehar, 2002).

  37. Adults utilize closure and its combination with collinearity and proximity to organize fragmented image contours into shapes. What is the developmental course of this ability?

  38. Developmental Research • 3-month-olds are able to rely on good continuation of contour elements, though their ability is far from adult-like, but they appear to be completely insensitive to closure (Gerhardstein, Kovacs, Ditre, & Feher, 2004). • Kindergartners may be sensitive to closure (Enns & Girgus, 1985). • We do not know of any study that directly examined the development of the ability to utilize closure for the perceptual grouping of shape in younger and older children.

  39. Comparing the performance of 5- and 10-year-old children and young adults in a visual search task (similar to the one used by Elder and Zucker, 1993) Task: search for a concave target among convex distractors.

  40. Basic Stimuli(similar to the ones used by Elder & Zucker, 1993): The line segments are the same for the concave and convex stimuli but their placement relative to each other differs, bending inward for the concave and outward for the convex. Therefore, the discrimination between the two stimuli requires grouping of the contour segments into coherent two-dimensional shapes. Concave Convex

  41. Open vs. Closed Stimuli • Task: search for a concave target among convex distractors. • Display size: 2, 6, or 10. • Dependent variables: Baseline RT (display size=2; measures response speed independent of search rate). Search rate - The slop of the RT function over display size.

  42. Results Accuracy: 5-year olds: 95.3% 10-year olds: 98.2% Adults: 97.5%

  43. Baseline RT (Display Size = 2, Target-present Trials) • RT improved with age. • Faster RTs for closed than for open stimuli. • Larger improvement with age for the open stimuli, indicating age-related change in target-distractor discriminability. Hadad & Kimchi, 2006

  44. RT Slopes (Target-present trials) • Closed stimuli: Equally efficient search for all age groups. • Open Stimuli:Inefficient search. Significant improvement with age. Hadad & Kimchi, in press

  45. Summary of Results • Children, like adults, are able to derive the shape of a closed figure, while encountering difficulty when closure is absent. • The age-related improvement for the open stimuli: improvement in spatial abilities

  46. Noncollinearvs. Collinear Stimuli Noncollinear Collinear

  47. Results Accuracy: 5-year olds: 96.7% 10-year olds: 98.2% Adults: 97.7%

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