20.02.2013

Talk @ NIP by Nora Umbach

Nora Umbach from the AG Forschungsmethoden und Mathematische Psychologie at the Eberhard Karls Universität Tübingen will give a talk entitled "Dimensionality of the Perceptual Space of Achromatic Surface Colors" at the AG NIP, Sand 6, on Monday the 25th of February at 15:00 hrs.

Talk by <link http: www.uni-tuebingen.de fakultaeten mathematisch-naturwissenschaftliche-fakultaet fachbereiche psychologie arbeitsbereiche forschungsmethoden-und-mathematische-psychologie arbeitsbereich nora-umbach.html external-link-new-window externen link in neuem>Nora Umbach - Abstract:

Lightness (perceived achromatic color) of a surface is influenced by perceptual processes like contrast induction as well as cognitive processes like interpretation of a scene. The experiments presented here aim at a better understanding of how cognitive processes are involved in the perception of lightness and how many perceptual dimensions we use to represent achromatic colors. The hypothesis is that one of these dimensions is introduced by interpretations of a complex stimulus situation. Stimuli of increasing complexity were presented in a room with controlled illumination in order to determine which context effects influence lightness. The presented stimuli were simple gray patches in the first experiment, classic infield-surround configurations in the second experiment, and infield-surround configurations which either induced transparency or not in the third experiment. Subjects performed same/different judgments in all experiments. Discrimination probabilities were analyzed using Fechnerian scaling followed by metric MDS to find the number of dimensions of achromatic color space. Results show that subjects use one perceptual dimension for stimuli without surround and two dimensions for more complex configurations.