Structural support for the perception of growth.

Previous studies have shown that the effects of a particular class of geometric transformations, known as cardioidal strain, are perceived as growth when applied to a variety of animate and even inanimate objects. The current study demonstrates that the effects of these growth transformations are not completely independent of the object undergoing change, but depend critically on certain structural characteristics. When cardioidal strain is applied to a straight-line, right-angle, robotlike structure, there is no consistent effect on the age level of the figure. However, as the structural contours become more curved and less angular, the effects of this transformation are seen as increasingly more like growth. In contrast, the effects of a shear transformation are not perceived as growth on any of the profiles. These findings are examined in light of the critical physical properties that may be responsible for this notion of biological forms as well as their implications for our understanding of the information about events.