In what is known as a reversed contrast display it has been found (Agostini & Galmonte, 1997, 2002) that a grey region surrounded by a black area can appear darker than an identical grey region surrounded by white, and the induction cannot be explained by assimilation. Both high- and low-level factors are simultaneously present in this configuration, but the former prevail in determining the effect. The present work was aimed to verify whether global grouping factors induction holds also for coloured displays. In this new version of Agostini & Galmonte's display we used red/yellow inducing backgrounds/corners, while induced regions (dashed lines) were orange. We tested also two control conditions, where we did not expect any effect: 1. inducer corners of the same orange as targets; 2. inducer corners replaced by disks having the same area and colour. Observers' task was to judge the colour of the induced regions on a red/yellow scale. Results are comparable to those obtained for lightness: The targets perceived colour is determined by global factors; in fact, orange was judged as reddish in the yellow corners/red background display and yellowish in the opposite one. Both controls provided no statistically significant difference. To conclude, it seems plausible that global induction overcomes local induction also for coloured displays.
A coloured version of Agostini & Galmonte's Necker cube display
GALMONTE, Alessandra;
2010-01-01
Abstract
In what is known as a reversed contrast display it has been found (Agostini & Galmonte, 1997, 2002) that a grey region surrounded by a black area can appear darker than an identical grey region surrounded by white, and the induction cannot be explained by assimilation. Both high- and low-level factors are simultaneously present in this configuration, but the former prevail in determining the effect. The present work was aimed to verify whether global grouping factors induction holds also for coloured displays. In this new version of Agostini & Galmonte's display we used red/yellow inducing backgrounds/corners, while induced regions (dashed lines) were orange. We tested also two control conditions, where we did not expect any effect: 1. inducer corners of the same orange as targets; 2. inducer corners replaced by disks having the same area and colour. Observers' task was to judge the colour of the induced regions on a red/yellow scale. Results are comparable to those obtained for lightness: The targets perceived colour is determined by global factors; in fact, orange was judged as reddish in the yellow corners/red background display and yellowish in the opposite one. Both controls provided no statistically significant difference. To conclude, it seems plausible that global induction overcomes local induction also for coloured displays.
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