John R. Pani

Global Spatial Organization by Individuals with Williams Syndrome

Williams syndrome is a genetically determined disorder with a characteristic cognitive profile. Overall IQ tends to be lower than in the normally developing population, performance on measures of linguistic ability is somewhat higher than would be expected given the levels of IQ typical for this group, and there is a particular weakness in visuospatial construction (e.g., block design tasks). A wellknown hypothesis about the deficit in visuospatial construction is that people with Williams syndrome are strongly inclined to be local spatial processors. We report a test of this hypothesis that used a visual search task sensitive to spontaneous global spatial organization. A sample of adults with Williams syndrome produced a pattern of data demonstrating that they spontaneously organize spatial displays at a global level. Indeed, individuals with Williams syndrome found it more difficult to change from global to local processing than participants with normal intelligence. We suggest that the primary problem with visuospatial construction in people with Williams syndrome is not in the salience of single levels of organization but rather in the difficulty of changing between organizations.

Spatial Reference Systems in the Comprehension of Rotational Motion

In certain simple rotations of objects, the orientation of the axis and planes of rotation can determine whether people are able to visualize the motion or perceive it as simple and coherent. This finding affords the opportunity to investigate the spatial reference systems used to define the orientation of the axis and planes of rotation. The results of two experiments suggest that the permanent environment is the primary reference system, apart from the rotating object, used for this purpose. Subjects also were able to use a local spatial environment to determine the orientation of the motion; some subjects were particularly adept at this. The viewer perspective, in contrast, was irrelevant as a reference system in these experiments. These results argue strongly for the primacy of environmental reference systems in the perception and imagination of orientation and extend the set of findings common between the comprehension of rotational motion and orientation-sensitive form perception.

Limits on the Comprehension of Rotational Motion: Mental Imagery of Rotations with Oblique Components

Mental imagery of rotational motion across variation in the orientation of a square to an axis of rotation, the orientation of the axis to the environment/viewer, and the starting orientation of the rotation were investigated in three experiments. The experimental method included specifying the particular rotations that subjects should consider and obtaining exact predictions of the outcomes of the rotations. When the square was normal to the axis and the axis was normal to the environment/viewer, performance was excellent. When either of these relationships was oblique, performance was quite good. When both of these relationships were oblique, nearly every subject made large errors on every problem. The difficulty of the double-oblique rotations was reduced when the initial orientation of the square was not canonical. Current views of the comprehension of rotational motion are discussed. It appears that the comprehension of rotational motion can be understood as an organization of the symmetric space traced out by the motion. People succeed in organizing this space when it is aligned with a principal spatial reference system.

Imagining Projective Transformations: Aligned Orientations in Spatial Organization.

Four experiments were conducted to investigate whether variations in orientation that profoundly affect the ability to imagine rotations also affect the ability to imagine projective transformations. For a basic rectilinear object and the three simpler Platonic Solids, imagining projective transformations (e.g., the casting of a shadow) was quite successful when the objects were aligned with the direction of projection. For the solids, this alignment occurred when the objects were generalized cylinders about axes aligned with the projection. As the objects were made more oblique to the projection, performance deteriorated markedly. When the objects were moderately aligned with the projection, performance depended on the orientation of the object and the orientation of the projection to the environment. We suggest that the imagination of projection and of rotation is a type of problem solving in which spatial structures are organized in relation to initially given properties of the objects and transformations. When there is alignment among the various structural components, this process of imagination works efficiently. Without such alignment, nonexperts often fail. We suggest that aligned (i.e., parallel and perpendicular) orientations are effective in spatial imagination because they are categorically distinct and singular, and they provide a critical form of redundancy.

Acquiring New Spatial Intuitions: Learning to Reason about Rotations

There are certain simple rotations of objects that most people cannot reason about accurately. Reliable gaps in the understanding of a fundamental physical domain raise the question of how learning to reason in that domain might proceed. Using virtual reality techniques, this project investigated the nature of learning to reason across the domain of simple rotations. Learning consisted of the acquisition of spatial intuitions: there was encoding of useful spatiotemporal information in specific problem types and a gradual accumulation of this understanding across the domain. This pattern of learning through the accumulation of intuitions is especially interesting for rotational motion, in which an elegant domain-wide kinematics is available to support insightful learning. Individual ability to reason about rotations correlated highly with mastery motivation, skill in fluid reasoning, and skill in reasoning about spatial transformations. Thus, general cognitive advantages aided the understanding of individual rotations without guaranteeing immediate generalization across the domain.

DETERMINANTS OF THE PERCEPTION OF ROTATIONAL MOTION : ORIENTATION OF THE MOTION TO THE OBJECT AND TO THE ENVIRONMENT

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.

Reports of Mental Imagery in Retrieval from Long-Term Memory

Phenomenal reports were obtained immediately after participants retrieved information from long-term memory. Data were gathered for six basic forms of memory (semantic, generic perceptual, recollective, motor skill, rote skill, cognitive skill) and for three forms of memory that asked for declarative information about procedural tasks (motor-declarative, rote-declarative, cognitive-declarative). The data show consistent reports of mental imagery during retrieval of information from the generic perceptual, recollective, motor-declarative, rote-declarative, and cognitive-declarative categories; much less imagery was reported for the semantic, motor, rote, and cognitive categories. Overall, the data provide support for the theoretical framework outlined in Brewer and Pani (1983).

Computer-based learning: interleaving whole and sectional representation of neuroanatomy.

The large volume of material to be learned in biomedical disciplines requires optimizing the efficiency of instruction. In prior work with computer‐based instruction of neuroanatomy, it was relatively efficient for learners to master whole anatomy and then transfer to learning sectional anatomy. It may, however, be more efficient to continuously integrate learning of whole and sectional anatomy. A study of computer‐based learning of neuroanatomy was conducted to compare a basic transfer paradigm for learning whole and sectional neuroanatomy with a method in which the two forms of representation were interleaved (alternated). For all experimental groups, interactive computer programs supported an approach to instruction called adaptive exploration. Each learning trial consisted of time‐limited exploration of neuroanatomy, self‐timed testing, and graphical feedback. The primary result of this study was that interleaved learning of whole and sectional neuroanatomy was more efficient than the basic transfer method, without cost to long‐term retention or generalization of knowledge to recognizing new images (Visible Human and MRI). Anat Sci Educ.

Item Difficulty in the Evaluation of Computer-Based Instruction: An Example from Neuroanatomy

This article reports large item effects in a study of computer‐based learning of neuroanatomy. Outcome measures of the efficiency of learning, transfer of learning, and generalization of knowledge diverged by a wide margin across test items, with certain sets of items emerging as particularly difficult to master. In addition, the outcomes of comparisons between instructional methods changed with the difficulty of the items to be learned. More challenging items better differentiated between instructional methods. This set of results is important for two reasons. First, it suggests that instruction may be more efficient if sets of consistently difficult items are the targets of instructional methods particularly suited to them. Second, there is wide variation in the published literature regarding the outcomes of empirical evaluations of computer‐based instruction. As a consequence, many questions arise as to the factors that may affect such evaluations. The present article demonstrates that the level of challenge in the material that is presented to learners is an important factor to consider in the evaluation of a computer‐based instructional system. Anat Sci Educ.

Cognitive Description and Change Blindness

Cognition depends on representations of the world that are much like descriptions. That is, processes of selection, organization, and categorization of the relations among things provide people with a view of the world that in principle could be different. A theoretical problem for a descriptional theory is the question of how the rich mapping of sensory detail available in perception is related to the descriptional character of information in higher level perception, memory, knowledge, and reasoning. In this paper, I review evidence in favour of a descriptional theory of cognition and suggest that work on change blindness clarifies the nature of the juncture between perception and cognition. In turn, work from the descriptional point of view clarifies the nature of change blindness. I discuss change blindness from this perspective for the topics of attention, recognition, and the adaptive use of information. I close with a discussion of new issues that are raised.