Figure 1.

Shows stimulus set of “buggles.” Each buggle consisted of one value along a continuous shape (aspect ratio) and color (hue) dimension. The shape dimension consisted of six equidistant metric steps and the color dimension consisted of 12 equidistant metric steps sampled from a continuous 360° color space (from right to left, ° 91 – 271° in 30° increments shown). Figure also shows experimental design. One of the central 5 shapes and one of the 12 colors was selected as the familiar item. The novel item on the similar test was novel by one metric step and the novel item on the dissimilar test was novel by three metric steps. The similar and dissimilar test were always on the same dimension and in opposite directions from the familiar item on the dimension.