Barbara Tversky

Animation: can it facilitate?

Graphics have been used since ancient times to portray things that are inherently spatiovisual, like maps and building plans. More recently, graphics have been used to portray things that are metaphorically spatiovisual, like graphs and organizational charts. The assumption is that graphics can facilitate comprehension, learning, memory, communication and inference. Assumptions aside, research on static graphics has shown that only carefully designed and appropriate graphics prove to be beneficial for conveying complex systems. Effective graphics conform to the Congruence Principle according to which the content and format of the graphic should correspond to the content and format of the concepts to be conveyed. From this, it follows that animated graphics should be effective in portraying change over time. Yet the research on the efficacy of animated over static graphics is not encouraging. In cases where animated graphics seem superior to static ones, scrutiny reveals lack of equivalence between animated and static graphics in content or procedures; the animated graphics convey more information or involve interactivity. Animations of events may be ineffective because animations violate the second principle of good graphics, the Apprehension Principle, according to which graphics should be accurately perceived and appropriately conceived. Animations are often too complex or too fast to be accurately perceived. Moreover, many continuous events are conceived of as sequences of discrete steps. Judicious use of interactivity may overcome both these disadvantages. Animations may be more effective than comparable static graphics in situations other than conveying complex systems, for example, for real time reorientations in time and space.

Distortions in memory for maps

Evidence is presented for systematic errors in memory for real and artificial maps, local environments, and visual forms. These errors are attributed to two heuristics that are derived from principles of perceptual organization. Maps of countries or localities are conceived of as figures in backgrounds. Remembering the absolute location of figures is difficult, and is facilitated by remembering locations relative to other figures and/or relative to the natural directions of the figure. In alignment, figures are lined up relative to one another, a phenomenon related to perceptual grouping by proximity. In rotation, the natural axes induced by a figure converge with frame axes (north-south, east-west, or horizontal, vertical), a phenomenon related to perceptual organization by common fate. Heuristic-induced errors occur in a variety of tasks, and even when subjects are explicitly forewarned. These heuristics may be invoked in forming representations as well as in inference, and function analogously to syntax in locating smaller elements in larger units.

Spatial mental models derived from survey and route descriptions

Abstract In four experiments, subjects read route or survey descriptions of naturalistic environments and then answered verbatim or inference questions from both perspectives and drew maps of the environments. In all studies, subjects were faster and more accurate to verbatim than to inference questions, suggesting that verbatim questions are verified against a representation of the text of the descriptions. Subjects were as fast and accurate to inference questions from the read perspective as from the new perspective, suggesting that inference questions are verified against a representation of the situation described by the text. Map drawings were very accurate for both description types. A separate group of subjects studied maps instead of descriptions, and their performance was comparable to that of description subjects on all tasks. Readers apparently form the same spatial mental models capturing the spatial relations between landmarks from both survey and route descriptions, and from maps.

Cognitive maps, cognitive collages, and spatial mental models

Although cognitive map is a popular metaphor for peoples mental representations of environments, as it is typically conceived, it is often too restrictive. Two other metaphors for mental representations are proposed and supported. Cognitive collages are consistent with research demonstrating systematic errors in memory and judgment of environmental knowledge. Yet, for some simple or well-known environments, people seem to have coherent representations of the coarse spatial relations among elements. These spatial mental models allow inference and perspectivetaking but may not allow accurate metric judgments.

What do architects and students perceive in their design sketches? A protocol analysis

The present research aims at examining what information architects think of and read off from their own freehand sketches, and at revealing how they perceptually interact with and benefit from sketches. We explored this in a protocol analysis of retrospective reports; each participant worked on an architectural design task while drawing freehand sketches and later reported what she/he had been thinking of during the design task. This research lies within the scope of examinations of why freehand sketches as external representation are essential for crystallizing design ideas in early design processes.

Searching Imagined Environments

Subjects read narratives describing directions of objects around a standing or reclimng observer, who was periodically reoriented. RTs were measured to identify which object was currently located beyond the observers head, feet, front, back, fight, and left. When the observer was standing, head/feet RTs were fastest, followed by front/back and then right/left. For the reclining observer, front/back RTs were fastest, followed by head/feet and then right/left. The data support the spatial framework model, according to which space is conceptualized in terms of three axes whose accessibility depends on body asymmetries and the relation of the body to the world. The data allow rejection of the equiavailability model, according to which RTs to all directions are equal, and the mental transformation model, according to which RTs increase with angular disparity from front.

Perceiving, remembering, and communicating structure in events.

How do people perceive routine events, such as making a bed, as these events unfold in time? Research on knowledge structures suggests that people conceive of events as goal-directed partonomic hierarchies. Here, participants segmented videos of events into coarse and fine units on separate viewings; some described the activity of each unit as well. Both segmentation and descriptions support the hierarchical bias hypothesis in event perception: Observers spontaneously encoded the events in terms of partonomic hierarchies. Hierarchical organization was strengthened by simultaneous description and, to a weaker extent, by familiarity. Describing from memory rather than perception yielded fewer units but did not alter the qualitative nature of the descriptions. Although the descriptions were telegraphic and without communicative intent, their hierarchical structure was evident to naive readers. The data suggest that cognitive schemata mediate between perceptual and functional information about events and indicate that these knowledge structures may be organized around object/action units.

Cross-cultural and developmental trends in graphic productions ☆

Abstract How does space come to be used to represent nonspatial relations, as in graphs? Approximately 1200 children and adults from three language cultures, English, Hebrew, and Arabic, produced graphic representations of spatial, temporal, quantitative, and preference relations. Children placed stickers on square pieces of paper to represent, for example, a disliked food, a liked food, and a favorite food. Two major analyses of these data were performed. The analysis of directionality of the represented relation showed effects of direction of written language only for representations of temporal concepts, where left-to-right was dominant for speakers of English and right-to-left for speakers of Arabic, with Hebrew speakers in between. For quantity and preference, all canonical directions except top-to-bottom were used approximately equally by all cultures and ages. The analysis of information represented in the graphic representations showed an age trend; more of the older children represented ordinal and some interval information in their mappings. There was a small effect of abstractness of concept on information represented, with more interval information represented by children for the more concrete concepts, space, time, quantity, and preference in that order. Directionality findings were related to language-specific left-to-right or right-to-left directionality and to universal association of more or better with upward. The difficulties in externally representing interval information were related to prevalent difficulties in expressing comparative information. Childrens graphic productions were compared to other invented notation systems, by children and by cultures, particularly for numbers and language.

Categories of environmental scenes

Abstract Environmental scenes are the settings in which human action occurs; since they constrain behavior, they are of interest to social, personality, and environmental psychologists. Scenes can also be viewed as a spatial generalization of objects, as well as the spatial contexts in which objects appear. As such, they are studied in perception and memory. Previous approaches to characterizing environments have relied on scaling techniques to yield a manageable number of dimensions or attributes by which environments can be compared. In contrast, the present research demonstrates development of a taxonomy of kinds of environmental scenes, where perceived attributes are obtained as a byproduct. A basic or preferred level of categorization in the taxonomy is also identified, based on measures of cognition, behavior, and communication. The basic level, for example, school, home, beach, mountains , corresponds to the level commonly used in the study of scene schemas in perception, memory, and environmental psychology, as well as to the level apparently most useful in other domains of knowledge concerned with environments, for example, architecture and geography.

Imagined transformations of bodies : an fMRI investigation

A number of spatial reasoning problems can be solved by performing an imagined transformation of ones egocentric perspective. A series of experiments were carried out to characterize this process behaviorally and in terms of its brain basis, using functional magnetic resonance imaging (tMRI). In a task contrast designed to isolate egocentric perspective transformations, participants were slower to make left-right judgments about a human figure from the figures perspective than from their own. This transformation led to increased cortical activity around the left parietal-temporal-occipital junction, as well as in other areas including left frontal cortex. In a second task contrast comparing judgments about inverted figures to judgments about upright figures (always from the figures perspective), participants were slower to make left-right judgments about inverted figures than upright ones. This transformation led to activation in posterior areas near those active in the first experiment, but weaker in the left hemisphere and stronger in the right, and also to substantial left frontal activation. Together, the data support the specialization of areas near the parietal-temporal-occipital junction for egocentric perspective transformations. These results are also suggestive of a dissociation between egocentric perspective transformations and object-based spatial transformations such as mental rotation.