Figure 8.

The three types of distortion used to create foils in Experiment 3. The cross shape that served as the sample image for a trial (labeled “sample image” at top) has horizontal extent X and vertical extent Y. The same-area distortion elongated one dimension and shortened the other, which changed aspect ratio X/Y, but preserved the surface area of the shape (proportional to X*Y). The same-aspect-ratio distortion elongated the shape along both dimensions equally, which significantly increased surface area but preserved the shape’s aspect ratio. The one-axis distortion produced changes intermediate to these two extremes by stretching only one axis, changing both surface area and aspect ratio moderately. Note that the one-axis distortion is the only case that kept one of the shape’s original axis dimensions constant. All of the above examples show concave images and positive values of d; negative values of d were also used. The shapes’ square backgrounds have also been distorted for emphasis, although they were not distorted in the actual stimuli.