Figure embeddedness depends on contour orientation

The “oblique effect” was studied using an embedded figures task in which complex patterns and hidden forms were rotated into different orientations. One set of stimuli (Series I) used patterns consisting either entirely of depending on rotation) horizontal and vertical line segments or entirely of obliques. A second set of stimuli (Series II) used patterns composed of horizontal, vertical, and oblique segments in equal proportions. With Series I, both form and complex pattern orientations changed with rotation. In Series II, rotation changed the orientation of the hidden forms, but not the relative proportion of contour orientations in the complex patterns. Significantly longer search times were required to find forms embedded within the obliquely oriented patterns of Series I. There were no significant differences in Series II. These results are discussed in terms of the role contextual contours may play in the detection of differently oriented form.