The framing effect with rectangular and trapezoidal surfaces: Actual and pictorial surface slant, frame orientation, and viewing condition

The perceived slant of a surface relative to the frontal plane can be reduc ed when the surface is viewed through a frame between the observer and the surface. Aspects of this framing effect were investigated in three experime nts in which observers judged the orientations-in-depth of rectangular and trapezoidal surfaces which were matched for pictorial depth. In experiments 1 and 2, viewing was stationary-monocular. In experiment 1, a frontal rect angular frame was present or absent during viewing. The perceived slants of the surfaces were reduced in the presence of the frame; the reduction for the trapezoidal surface was greater, suggesting that conflict in stimulus i nformation contributes to the phenomenon. In experiment 2, the rectangular frame was either frontal or slanted; in a third condition, a frame was trap ezoidal and frontal. The conditions all elicited similar results, suggestin g that the framing effect is not explained by pictorial perception of the d isplay, or by assimilation of the surface orientation to the frame orientat ion. In experiment 3, viewing was moving-monocular to introduce motion para llax; the framing effect was reduced, being appreciable only for a trapezoi dal surface. The results are related to other phenomena in which depth perc eption of points in space tends towards a frontal plane; this frontal-plane tendency is attributed to heavy experimental demands, mainly concerning im poverished, conflicting, and distracting information.