RESUMEN
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. Experiment 2 shows that the direction of these lightness effects is not influenced by the luminance of the size-contrast inducers. Experiment 3 shows that a similar lightness effect is also observed in modified Ebbinghaus size-contrast displays. Experiment 4 tested the presence of the size-contrast illusion in the stimuli used in experiments 2 and 3.
Asunto(s)
Sensibilidad de Contraste , Iluminación , Ilusiones Ópticas , Percepción del Tamaño , Adolescente , Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Adulto JovenRESUMEN
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 9.13, 10.33, and 10.46%.
Asunto(s)
Sensibilidad de Contraste , Ilusiones Ópticas , Reconocimiento Visual de Modelos , Percepción del Tamaño , Adulto , Femenino , Humanos , Masculino , Adulto JovenRESUMEN
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. Odors that have emotionally loaded content could produce older memories. Common odors with well-known names have been used. In Exp. 1 the names were shown, and the subjects were asked to imagine the corresponding odors; subsequently those odorants were presented. In Exp. 2 at first the odorants were presented and subsequently their names, printed one each per white card. The subjects were requested to provide written free associations. At the end of each session they scored a semantic differential. The hypothesis that emotionally loaded associations are more frequent when evoked by odorants seems confirmed, supported also by some reliable differences between the profiles for olfactory verbal stimuli. The evaluation of olfactory stimuli did not differ from one experiment to the other; verbal stimuli, on the contrary, are differently evaluated if the corresponding odorants were presented before or after their labels.