A vase, or two faces

The figure-ground illusion is commonly experienced in the illustration of a white vase whose outline is created by two black profiles. Britannica Scholars: illusion

At any moment you can see either the white vase, in the centre, as the figure, or the black profiles on each side, in which case the white is seen as the ground. Britannica Scholars: illusion

The fluctuations of figure and ground may occur even without conscious effort. Britannica Scholars: illusion Seeing one aspect usually excludes seeing the other. Britannica Scholars: illusion

In the figure-and-ground illustration, the vase appears against the dark background, or two framed silhouettes of heads are seen against the white background. Britannica Students: illusion

Rubin’s 1915 thesis

The Illusions Index credits the figure to Edgar John Rubin (1886–1951), a Danish psychologist and philosopher. The Illusions Index: Rubin’s vase The vase-and-faces figure was first published in Rubin’s doctoral thesis, Synsoplevede figurer, in 1915. The Illusions Index: Rubin’s vase

In July 1915 Edgar Rubin, a 28-year-old Dane, defended a doctoral thesis titled Synsoplevede Figurer (Visually experienced figures) at the University of Copenhagen. Pind, The Psychologist (BPS)

It was in this work that Rubin first elucidated the figure–ground distinction, now a staple of introductory psychology textbooks. Pind, The Psychologist (BPS) It was also in that thesis that he presented his celebrated illustration. Pind, The Psychologist (BPS)

In the dissertation Rubin compared “areal figures”, such as the classic vase, with line or stroke figures drawn with a pencil. Pind, The Psychologist (BPS)

Edgar Rubin was born in Copenhagen in 1886. Pind, The Psychologist (BPS) He became Professor of Psychology at the University of Copenhagen in 1922, and held the post until his death in 1951. Pind, The Psychologist (BPS)