creators_name: de Weert, Charles M. M. creators_name: van Kruysbergen, Noud A.W.H type: journalp datestamp: 1998-05-11 lastmod: 2011-03-11 08:54:10 metadata_visibility: show title: Assimilation: central and peripheral effects ispublished: pub subjects: psy-phys full_text_status: public keywords: assimilation, spreading abstract: Assimilation and contrast have opposite effects: Contrast leads to an increase of perceived differences between neighbouring fields, whereas assimilation leads to a reduction. It is relatively easy to demonstrate these effects, but the precise localisation of these effects in the perceptual system is not yet possible. In an experiment the strength of assimilation effects was modified by adding spatial noise. By varying the localisation in perceived space of the added noise (by presentation of the noise pattern with different binocular disparities) the masking effect of this noise can be influenced. Masking caused by binocularly disparate noise is less than masking caused by binocularly non-disparate noise. Our conclusion is that the effect at least partly occurs beyond the (binocular) locus of separation in different depth planes. A similar approach, involving moving noise, will also be presented. Finally, several demonstrations show that images that are peripherally similar can give rise to differences in the perceived amount of assimilation. These effects further indicate that a central mechanism is involved in assimilation. date: 1997 date_type: published publication: Perception volume: 26 pagerange: 1217-1224 refereed: TRUE citation: de Weert, Charles M. M. and van Kruysbergen, Noud A.W.H (1997) Assimilation: central and peripheral effects. [Journal (Paginated)] document_url: http://cogprints.org/659/1/bressan5.html