The first purpose of this thesis was to design and complete psychophysical experiments for scaling lightness and lightness differences for achromatic percepts above and below the lightness of diffuse white (L*=100). Below diffuse white experiments were conducted under reference conditions recommended by CIE for color difference research. Overall a range of CIELAB lightness values from 7 to 183 ...

Lightness of a grey target on a uniform light (or dark) surround changes by articulating the surround (articulation effect). To elucidate the processing of lightness underlying the articulation effect, the present study introduced transparency over a dark surround and investigated its effects on lightness of the target. The transparency was produced by adding a contiguous external field to the ...

Observers see a white triangle on the top of three black disks; the white triangle appears lighter, although it has the same luminance of the white background. Also squared or irregular “anomalous” figures can be created (Kanizsa & Gerbino, 1987). Several competing explanations have been put forward for the effect (Dumais, & Bradley, 1976; Coren, 1991; Ramachandran & Rogers-Ramachandran, 2005),...

Brightness (perceived intensity) and lightness (perceived reflectance) matching were investigated in seven well-known visual stimuli that contain a visible shadow or transparent overlay. These stimuli are frequently upheld as evidence that low-level spatial filtering is inadequate to explain brightness/lightness illusions and that additional mid- or high-level mechanisms are required. The argum...

Citation: Gilchrist A (2015) Commentary: What visual illusions tell us about underlying neural mechanisms and observer strategies for tackling the inverse problem of achromatic perception. A commentary on What visual illusions tell us about underlying neural mechanisms and observer strategies for tackling the inverse problem of achromatic perception. Blakeslee and McCourt state repeatedly that ...

...................................................................................................................................... i Acknowledgements .................................................................................................................... ii List of Publications .........................................................................................................

The strength of amodal completion is known to be modulated by contour relationships and global shape. Some researchers have shown that amodal completion also depends on surface similarity, but they have not distinguished the relative importance of similarity in surface representations either pre or post lightness constancy. In the experiments reported here, we aimed to determine whether amodal ...

The past quarter century has witnessed considerable advances in our understanding of Lightness (perceived reflectance), Brightness (perceived luminance) and perceived Transparency (LBT). This review poses eight major conceptual questions that have engaged researchers during this period, and considers to what extent they have been answered. The questions concern 1. the relationship between light...