Determinants of the perception of rotational motion: Orientation of the motion to the object and to the environment.

Abstract

The results of two experiments suggest that strong constraints on the ability to imagine rotations extend to the perception of rotations. Participants viewed stereographic perspective views of rotating squares, regular polyhedra, and a variety of polyhedral generalized cones, and attempted to indicate the orientation of the axis and planes of rotation in terms of one of the 13 canonical directions in 3D space. When the axis and planes of a rotation were aligned with principal directions of the environment, participants could indicate the orientation of the motion well. When a rotation was oblique to the environment, the orientation of the object to the motion made a very large difference to performance. Participants were fast and accurate when the object was a generalized cone about the axis of rotation or was elongated along the axis. Variation of the amount of rotation and reflection symmetry of the object about the axis of rotation was not powerful.The study of motion and spatial transformation has long been central in mathematics and the physical sciences, and recently it has become the focus of much work in the study of perception and spatial cognition. Rotation, for example, is a fundamental form of motion (e.g., Gibson, 1957;Shepard, 1984), and the study of mental imagery has benefited greatly from the investigation of mental imagery of rotation (see Shepard & Cooper, 1982). Across the study of spatial cognition, it has become clear that some forms of spatiotemporal structure are cognitively simple for the typical person, whereas other forms are quite complex and difficult. This distinction is familiar from work on the spatial organization of elementary forms (e.g., Garner, 1974;Palmer, 1977;Wertheimer, 1950), but it applies also to a great variety of familiar or three-dimensional (3D) structures and events (e.g., Hinton, 1979;McCloskey, 1983;Pani, 1993;Pani, Zhou, & Friend, 1995;Proffitt, Kaiser, & Whelan, 1990;Tversky, 1981).Consider simple rotational motion, the topic of this article. In simple rotation, all of the points on a rotating object move, with common angular velocity, in circles about an axis fixed in space. The planes of these circles are parallel to each other and normal to the axis (e.g., Todd, 1982). In contrast, if the axis and planes of rotation change orientation during the motion, the rotation is no longer physically simple. Fundamental parameters of simple rotation include the orientation of the axis and planes of rotation to the environment and the orientation of the rotating object to the axis and planes of rotation (see Pani, 1989,

Fitting objects into holes: On the development of spatial cognition skills.

“…The more spatially complicated a task is, that is to say the more steps you must imagine, the more you have to realize and plan. When adults judge direction, they perform worse when the rotation angle is oblique than when it is vertical or horizontal (Shiffrar and Shepard 1991;Pani 1993;Pani, William et al 1995;Pani, Jeffres et al 1996), probably because humans discern the vertical and horizontal in the environment more easily (Howard 1982).…”

Systems of Spatial Reference in Human Memory

“…In Experiments 2-5, we explored the role of the external environment more systematically, using a paradigm motivated by the work of Pani and his colleagues (Pani & Dupree, 1994;Pani, Williams, & Shippey, 1995). Pani and Dupree (1994) manipulated the correspondence among three spatial reference systems: (a) the permanent spatial environment defined by the gravitational upright and the structure provided by the floor, ceiling, and walls; (b) a local spatial environment defined by a wooden box in which the stimuli were mounted; and (c) the perspective of the observer defined by the orientation of the head (assuming forward gaze direction).…”

Differential effects of object orientation on imaginary object /viewer transformations

“…In past decades, the importance of object orientations on mental rotation has been established in various studies on object rotations (e.g., Pani, 1993;Pani, William, & Shippey, 1995;Parsons, 1995). Whereas these studies established the influence of the orientation of the object axis on object rotation, the present goal was to investigate whether the direction of the object axis would be found to have different effects on the object-based and viewer-based conditions.…”