Lightness effects in Delboeuf and Ebbinghaus size-contrast illusions.

We examined lightness effects observed in Delboeuf and Ebbinghaus size-contrast illusions. Results of four experiments are reported. Experiment 1 was conducted with Delboeuf-like stimuli and shows that the disk that appears bigger appears either lighter or darker than the disk that appears smaller, depending on the contrast polarity between disks and background.

Illusory lightness in the Delboeuf figure.

A white disk presented inside a small concentric circle (a display like the Delboeuf figure) looks lighter than when inside a larger one. The magnitude of the effect was measured with 20 observers (10 women, 10 men; ages 19 to 26 years). The decrements in luminance of the disk inside the smaller circle, in order to match the lightness of the disk inside the larger circle, are reported for three different grey backgrounds and correspond to 9.

Verbal versus olfactory cues: affect in elicited memories.

Verbal processing has a reduced role for olfactory stimuli. It is difficult to provide a label for an odor experience. Odor perception can retrieve memories of life events with personal meaning and elicit affective experiences.