Showing papers by "Leonard S. Mark published in 1986"

Structural support for the perception of growth.

Abstract: 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.

Seated Posture in the Dynamic Mode- Preliminary Results:

Abstract: Many advanced ergonomic chairs currently available allow operators to utilize a dynamic mode of operation in which supporting surfaces (seat pan and backrest) have some degree of motion in response to body movement. However, there is a lack of behavior data demonstrating the effectiveness of this option. The current study involves a postural analysis of VDT operators who alternated between copy-intensive and screen-intensive tasks while utilizing a chair which allowed dynamic movement between forward tilting and backwards leaning postures. Results indicated that subjects tended to utilize the extreme positions of the chair.