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Course Description

 

 

 

Color and Form in Visual Perception

 

Rob van Lier and  Charles de Weert

 

 

This course is given by two persons. One has his main background in colour vision (Charles de Weert), the other in object perception (Rob van Lier). Both of them are interested in the interactions between the two areas.

Rob van Lier (1960) started his education as a physics and mathematics teacher. After that, he studied experimental psychology in Nijmegen. His PhD–thesis was entitled ‘Simplicity of visual shape’, and he is now a research fellow and assistant  professor at the Nijmegen Institute for Cognition and Information at the University of Nijmegen. http://www.nici.kun.nl/~robvl

Charles de Weert (1942) studied experimental physics in Utrecht. He became involved in colour vision at the end of the sixties. His PhD thesis was concerned with dichoptic colour and brightness experiments. He is professor in psychophysics and was the director of the Nijmegen Institute for Cognition and Information from 1987 until may 2003. Since then he is the dean of the faculty of Social Sciences at the university of Nijmegen. http://www.nici.kun.nl/People/WeertdeCMM/index.html

 

 

DAY 1, Monday 12 july

Morning session (2 * 45 minutes)

Title From images to interpretations Part I. Lecturer: Rob van lier

Contents In the first part, a brief overview of form perception will be given. In the second part, there will be special attention to viewpoint dependency and viewpoint independency in object perception and to our own information-based approach in dealing with these aspects.

 

Reference:

Van Lier, R. (2001). Simplicity, Regularity, and Perceptual interpretations: A Structural Information Approach. In T. Shipley & P. Kellman (eds.), From Fragments to Objects: Segmentation in Vision. New York: Elsevier, 331-352.

Van Lier, R. (1999). Investigating global effects in visual occlusion: From a partly occluded square to the back of a tree trunk. Acta Psychologica (Special issue: ‘Object perception and memory’) 102, 203-220.

 

Additional Readings:

S. Palmer (1999). Vision science:  from photons to phenomenology.  Chapters 5-8.

Van Lier, R., & Wagemans, J. (1999). From images to objects: Global and local completions of self-occluded parts. Journal of Experimental Psychology: Human Perception and Performance, 25, 1721-1741.

Van Lier, R. (2002).  A double neon colour illusion. Perception. 31, 31-38.

 

Afternoon session (45 minutes)

Further elaboration on a experimental methods, demonstrations, and discussion

 

 

DAY 2, Tuesday 13 july

Morning session (2 * 45 minutes)

Title Colour vision: an overview. Lecturer: Charles de Weert

Contents In this lecture an overview is given of colour vision and its usability in information processing. Special attention will be given to effects of isoluminance.

 

Reference:

Charles M.M. de Weert (2002).  Color Vision: psychophysics and physiology-a brief historical Sketch. In Theories, Technologies, instrumentatlities of Color: psychophysical and historiographical perspectives. Eds.  Barbara Saunders and Jaap van Brakel,  University Press  of America, Lanham, New York, Oxford, 2002,  327-342.

See for additional colour demomstrations: http://www.nici.kun.nl/~deweert/Isoluminance/

 

Afternoon session (45 minutes)

Technical workshop on color. A handout of the powerpoint presentation will be provided.

 

Additional Readings:

Frequently asked Questions on Color (author: Poynton)

S. Palmer (1999). Vision science:  from photons to phenomenology.  Chapter 3.

 

 

DAY 3,Wednesday 14 july

Morning session (2 * 45 minutes)

Title From images to interpretations Part II.  Lecturer: Rob van Lier

Contents This lecture deals with various recent experiments in our group. The topics range from low versus high level grouping, visual completion, to effects of luminance on form perception. Recent brain imaging studies on visual completion will be discussed as well.

 

Reference:

Koning, A. & Van Lier, R. (2003). Object-based connectedness facilitates matching. Perception & Psychophysics, 65, 1094-1102.
De Wit, T. & Van Lier, R. (2002). Global visual completion of quasi-regular shapes. Perception, 31, 969-984.

 

Additional Readings

S. Palmer (1999). Vision science:  from photons to phenomenology.  Chapters 5-8.

Van Lier, R., & Wagemans, J. (1998). Effects of physical connectivity on the representational unity of multi-part configurations. Cognition, 69, B1-B9.

 

Afternoon session (45 minutes)

Further elaboration on a experimental methods, demonstrations, and discussion

 

 

DAY 4,Thursday 16 july

Morning session (2 * 45 minutes)

Title Assimilation and Contrast Lecturer: Charles de Weert

Contents An overview  on assimilation and contrast effects will be given with special attention to the influence of organisational aspects on assimilation and contrast. 

 

Reference:

Ch.M.M. de Weert  and A.H.W.van Kruysbergen. (1987). Subjective contour strength and perceptual superimposition:  transparency as a special case. In "Perception of illusory contours" .S.Petry and G.meyer(eds),Springer, 165-170

Ch.M.M. de Weert (1991) Assimilation  versus  Contrast , in A.Valberg en B.Lee (eds),' From Pigments to Perception',Plenum. New York, 1991,305-311

Ch.M.M.de Weert and L.Spillmann(1995), Assimilation: asymmetry between brightness and darkness. Vision Research , 35,1413-1420

Ch.M.M. de Weert and A.W.H.van kruysbergen (1997).  Assimilation: central and peripheral effects. Perception, 26,1217-1224

 

Additional Readings

Van Lier, R., & Wagemans J. (1997). Perceptual grouping measured by color assimilation: Regularity versus Proximity. Acta Psychologica, (Special issue: ‘Higher-level cortical processing of color’) 97, 37-70.

 

Afternoon session (45 minutes)

Further elaboration on a experimental methods, demonstrations, and discussion

 

 

DAY 5, Friday 16 july

Morning session (2 * 45 minutes)

Title Gestalt-effects  measured in binocular rivalry conditions. Lecturers: Charles de Weert and Rob van Lier

Contents In this lecture special attention will be given to interocular gestalt formation, based on colour or form, as can be measured in dichoptic presentations.

 

Reference:

Van Lier, R. & De Weert, Ch. (2003). Intra- and Interocular activations during dichoptic suppression. Vision Research, 43, 1111-1116.

Charles M.M. de Weert, Peter R.Snoeren and Arno Koning (2004). Interactions between binocular rivalry and Gestalt formation. In preparation for Vision Research.

 

Additional Readings

Charles M.M. de Weert: Interocular gestalt formations

 

Afternoon session (45 minutes)

Further elaboration on a experimental methods, demonstrations, and discussion

More specifically, experiments in colour-form gestalt rivalry.