The face-cube illusion by Jean Beuchet.

The face-cube illusion was made by Jean Beuchet in 1966 (as indicated in the device) and this effect was not published. For this reason, it seems important to present this visual phenomenon. The effect is obtained from connected curved wire construction presented in three-dimensional space.

Color appearance of spatial patterns compared by direct estimation and conjoint measurement.

Perceptual scales of color saturation obtained by direct estimation (DE) and maximum likelihood conjoint measurement (MLCM) were compared for red checkerboard patterns and uniform red squares. For the DE task, observers were asked to rate the saturation level as a percentage, indicating the chromatic sensation for each pattern and contrast. For the MLCM procedure, observers judged on each trial which of two stimuli that varied in chromatic contrast and/or spatial pattern evoked the most salient color.

Optimizing the strength of the Bourdon effect by varying the triangle arrangement.

The Bourdon illusion refers to the perceived bentness of the straight collinear edges when two right-angled triangles are placed apex to apex. We studied this illusion using a cancellation method. In the first of three experiments, we manipulated the apex angle, with six different angles ranging from 4° to 45°.

Neural circuits for long-range color filling-in.

Surface color appearance depends on both local surface chromaticity and global context. How are these inter-dependencies supported by cortical networks? Combining functional imaging and psychophysics, we examined if color from long-range filling-in engages distinct pathways from responses caused by a field of uniform chromaticity. We find that color from filling-in is best classified and best correlated with appearance by two dorsal areas, V3A and V3B/KO.