Biomedical subjects

Arno Koning

Publications and source records attributed to Arno Koning.

4 recordsLinked to original sources

PubMed2005

Interactions between binocular rivalry and Gestalt formation.

A question raised a long time ago in binocular rivalry research is whether the phenomenon of binocular rivalry is purely determined by local stimulus properties or that global stimulus properties also play a role. More specifically: do coherent features in a stimulus influence rivalrous behavior? After decades of underexposure of the subject, recently this question seemed to be answered in the affirmative. This paper presents additional evidence for an influence of coherent features. In an experiment in which eye movements cannot bias conclusions it is demonstrated that Gestalt formation influences binocular rivalry positively, i.e., stronger Gestalts have longer total dominance times. Gestalt formation appears to intervene in the states of dominance ("what"), not directly in the dominance durations ("how long"). This generates questions about the nature of interactions between binocular rivalry and Gestalt formation. Gestalt formation seems to be fed by signals that are generated after binocular convergence and only leaves its mark on binocular rivalry by feedback to monocular channels, a conclusion which has been drawn before by Alais and Blake [Alais, D., & Blake, R. (1998). Interaction between global motion and local binocular rivalry. Vision research 38, 637-644].

Adult↗

PubMed2004

No symmetry advantage when object matching involves accidental viewpoints.

The presupposed advantage of symmetrical objects over asymmetrical objects was investigated in an object matching task, using accidental and non-accidental viewpoints. In addition, the accidental views could be symmetric or asymmetric. When two non-accidental views were presented, symmetrical objects were matched faster than asymmetrical objects. When an accidental view was presented first (followed by a non-accidental view), the matching of symmetrical objects was equal to that of asymmetrical objects. When a non-accidental view was presented first (followed by an accidental view), matching was again equal for the symmetrical and asymmetrical objects, although much faster compared with the opposite sequence of presented views. No effects of image symmetry in the accidental viewpoints were found. Apparently, the advantage of symmetrical objects over asymmetrical objects is only present in object matching when 3-D object structures are visible.

Adolescent↗

PubMed2004

Mental rotation depends on the number of objects rather than on the number of image fragments.

It is often intuitively assumed that disconnected image fragments result in a representation of separate objects. When objects are partly occluded, disconnected image fragments can still result in a representation of a single object, based on visual completion. In a simultaneous matching task, displays showing one object, partly occluded objects, or two objects were compared with each other. When only a translation was required to match pairs of displays, one-object displays were matched faster than both occluded-object and two-object displays, which did not differ significantly from each other. When mental rotation and translation were required, the one-object displays were again matched the fastest. In addition, an advantage for occluded-object displays compared with two-object displays was found. We conclude that when the generation of a mental representation is likely, object-based connectedness determines object matching. Mental rotation then seems to depend on the number of objects rather than on the number of image fragments.

Adolescent↗

PubMed2003

Object-based connectedness facilitates matching.

In two matching tasks, participants had to match two images of object pairs. Image-based (IB) connectedness refers to connectedness between the objects in an image. Object-based (OB) connectedness refers to connectedness between the interpreted objects. In Experiment 1, a monocular depth cue (shadow) was used to distinguish different relation types between object pairs. Three relation types were created: IB/OB-connected objects, IB/OB-disconnected objects, and IB-connected/OB-disconnected objects. It was found that IB/OB-connected objects were matched faster than IB/OB-disconnected objects. Objects that were IB-connected/OB-disconnected were matched equally to IB/OB-disconnected objects. In Experiment 2, stereoscopic presentation was used. With relation types comparable to those in Experiment 1, it was again found that OB connectedness determined speed of matching, rather than IB connectedness. We conclude that matching of projections of three-dimensional objects depends more on OB connectedness than on IB connectedness.

Adult↗