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Biomedical subjects

B Tversky

Publications and source records attributed to B Tversky.

At least 19 recordsLinked to original sources
PubMed2001

Event structure in perception and conception.

Events can be understood in terms of their temporal structure. The authors first draw on several bodies of research to construct an analysis of how people use event structure in perception, understanding, planning, and action. Philosophy provides a grounding for the basic units of events and actions. Perceptual psychology provides an analogy to object perception: Like objects, events belong to categories, and, like objects, events have parts. These relationships generate 2 hierarchical organizations for events: taxonomies and partonomies. Event partonomies have been studied by looking at how people segment activity as it happens. Structured representations of events can relate partonomy to goal relationships and causal structure; such representations have been shown to drive narrative comprehension, memory, and planning. Computational models provide insight into how mental representations might be organized and transformed. These different approaches to event structure converge on an explanation of how multiple sources of information interact in event perception and conception.

Causality↗
PubMed2001

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.

Analysis of Variance↗
PubMed2000

Biased retellings of events yield biased memories.

When people retell events, they take different perspectives for different audiences and purposes. In four experiments, we examined the effects of this postevent reorganization of events on memory for the original events. In each experiment, participants read a story, wrote a biased letter about one of the story characters, and later remembered the original story. Participants' letters contained more story details and more elaborations relevant to the purpose of their retellings. More importantly, the letter perspective affected the amount of information recalled (Experiments 1, 3, and 4) and the direction of the errors in recall (Experiments 1 and 3) and recognition (Experiment 2). Selective rehearsal plays an important role in these bias effects: retelling involves selectively retrieving and using story information, with consequent differences in memory. However, biased memory occurred even when the biased letters contained little, if any, specific information (Experiment 4) or contained the same amount and kinds of story information as a neutral control condition (Experiment 3). Biased memory is a consequence of the reorganizing schema guiding the retelling perspective, in addition to the effects of rehearsing specific information in retelling.

Adult↗
PubMed1999

Imagined transformations of bodies: an fMRI investigation.

A number of spatial reasoning problems can be solved by performing an imagined transformation of one's 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 figure's 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 figure's 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.

Adult↗
PubMed1999

Mental representations of perspective and spatial relations from diagrams and models.

In previous research (D. J. Bryant, B. Tversky, & N. Franklin, 1992; N. Franklin & B. Tversky, 1990), the authors showed that spatial knowledge conveyed by descriptions and direct experience induces participants to take the perspective of a character surrounded by objects. In this study, the authors used models and diagrams to convey the same information. With models, as with descriptions and experience, participants adopted the character's perspective (the spatial framework analysis). With diagrams, participants took an outside perspective (the intrinsic computation analysis). Even when informationally equivalent, different depictions made salient different aspects of the world. When instructed, however, participants were able to take either the inside or the outside perspective in memory for both diagrams and models. Depth cues in depictions also govern participants' perspective. When diagrams contained rich pictorial depth cues, participants used the spatial framework analysis, and when models were viewed without access to depth cues, participants relied on the intrinsic computation analysis.

Adult↗
PubMed1999

Bars and lines: a study of graphic communication.

Interpretations of graphs seem to be rooted in principles of cognitive naturalness and information processing rather than arbitrary correspondences. These predict that people should more readily associate bars with discrete comparisons between data points because bars are discrete entities and facilitate point estimates. They should more readily associate lines with trends because lines connect discrete entities and directly represent slope. The predictions were supported in three experiments--two examining comprehension and one production. The correspondence does not seem to depend on explicit knowledge of rules. Instead, it may reflect the influence of the communicative situation as well as the perceptual properties of graphs.

Adult↗
PubMed1997

Indexing events in memory: evidence for index dominance.

Research on narrative comprehension and autobiographical memory converge on three hypotheses which make different predictions about event organisation. The availability of different event components as indexes may explain the convergence on three hypotheses rather than one. In this paper, three experiments assessed event indexing in narratives with different available indexes. In Experiment 1, participants read event descriptions organised by character or time. In Experiment 2, event descriptions were organised by character or location. In Experiment 3, participants read event descriptions where events were grouped by activity. In each experiment, memory could be organised by any of the available components alone, by both components, or by using the organisation imposed by the discourse. Participants indexed events by character in Experiment 1, re-indexing information when necessary. Results of Experiment 2 indicated equal use of character and location indexes. In this case, participants used the discourse organisation. In Experiment 3, participants indexed events using activity groupings, again re-indexing events when necessary. Results are interpreted as indicating reliance on a single organising index with flexibility in the selection of different event components as indexes.

Cues↗
PubMed1995

Spatial concepts and perception of physical and diagrammed scenes.

The accessibility of objects in mental spatial frameworks depends on their relation to the spatial axes of the world and people's typical interactions with space. The current study investigated perception of space. Subjects viewed either a physical model of a person surrounded by objects (Exp. 1) or diagrams of scenes (Exp. 2). Subjects named objects at directions from their own external perspective. For physical scenes, subjects were faster to name objects at Above/Below locations, followed by Front/Behind locations, followed by Left/Right locations. This finding indicates that subjects used spatial frameworks to locate objects perceptually. For diagrams, response times to name objects did not conform to this pattern, perhaps because the spatial axes of a diagram do not correspond to stable spatial axes of the world.

Adolescent↗
PubMed1992

Descriptions and depictions of environments.

Subjects studied maps with the expectation that they would draw or describe them from memory. In fact, subjects did both. Order of drawing or describing landmarks revealed the mental organization of environments. Organization was quite similar across maps and descriptions of the same environments, revealing hierarchical structures based on spatial and functional features of the environments and on conventions for sequencing the landmarks.

Adult↗
PubMed1992

Switching points of view in spatial mental models.

In six experiments, subjects read narratives describing varying spatial scenes with more than one point of view. They were probed with questions about objects located in six directions from each character's point of view. Subjects' response times were consistent with a one place-one perspective rule. They seemed to form separate mental models for separate places and to take a character's perspective when there was only one relevant character in a scene, but they seemed to take a neutral perspective when there was more than one probed point of view, rather than switch perspectives.

Adult↗
PubMed1992

Structure and strategy in encoding simplified graphs.

Tversky and Schiano (1989) found a systematic bias toward the 45 degrees line in memory for the slopes of identical lines when embedded in graphs, but not in maps, suggesting the use of a cognitive reference frame specifically for encoding meaningful graphs. The present experiments explore this issue further using the linear configurations alone as stimuli. Experiments 1 and 2 demonstrate that perception and immediate memory for the slope of a test line within orthogonal "axes" are predictable from purely structural considerations. In Experiments 3 and 4, subjects were instructed to use a diagonal-reference strategy in viewing the stimuli, which were described as "graphs" only in Experiment 3. Results for both studies showed the diagonal bias previously found only for graphs. This pattern provides converging evidence for the diagonal as a cognitive reference frame in encoding linear graphs, and demonstrates that even in highly simplified displays, strategic factors can produce encoding biases not predictable solely from stimulus structure alone.

Bias↗
PubMed1991

Parts and the basic level in natural categories and artificial stimuli: comments on Murphy (1991)

Natural taxonomies consist of categories that vary in level of abstraction. Categories at the basic level, such as chair and apple, are preferred in a broad range of situations (Rosch, Mervis, Gray, Johnson, & Boyes-Braem, 1976). Several studies have revealed qualitative differences between the basic level and other levels. For example, Tversky and Hemenway (1984) presented evidence that parts proliferative at the basic level; they proposed that parts link the appearance of category members with their functions. Although not taking issue with these findings, Murphy (1991) investigated whether parts are necessary or sufficient for a basic level. In an attempt to demonstrate that parts are not necessary, Murphy used artificial stimuli that did not capture the essential features of natural taxonomies. These discrepancies preclude any conclusions based on his studies. Murphy's data also do not support his claim that parts are not sufficient for a basic level. Finally, it is unlikely that pursuing questions of necessity or sufficiency will produce insights into human categorization.

Adult↗
PubMed1989

Perceptual and conceptual factors in distortions in memory for graphs and maps.

We propose that representations of visual stimuli are a consequence of both perceptual and conceptual factors that may be revealed in systematic errors in memory. Three experiments demonstrated increased (horizontal or vertical) symmetry in perception and memory of nearly symmetric curves in graphs and rivers in maps. Next, a conceptual factor, an accompanying description biasing toward symmetry or asymmetry, also distorted memory in the expected direction for the symmetric descriptions. In the two final experiments, we investigated conceptual factors in selection of a frame of reference. Subjects remembered lines in graphs, but not in maps, as closer to the imaginary 45 degrees line. Combined with earlier research, this suggests that the reference frame for map lines is the canonical axes and for graph lines, the imaginary 45 degrees line.

Adult↗
PubMed1987

Cognitive constraints on ordering operations: the case of geometric analogies.

Many tasks (e.g., solving algebraic equations and running errands) require the execution of several component processes in an unconstrained order. The research reported here uses the geometric analogy task as a paradigm case for studying the ordering of component processes in this type of task. In solving geometric analogies by applying mental transformations such as rotate, change size, and add a part, the order of performing the transformations is unconstrained and does not in principle affect solution accuracy. Nevertheless, solvers may bring cognitive constraints with them to the analogy task that influence the ordering of the transformations. First, we demonstrate that solvers have a preferred order for performing mental transformations during analogy solution. We then investigate three classes of explanations for the preferred order, one based on general information processing considerations, another based on task-specific considerations, and a third based on individual differences in analogy ability. In the first and third experiments, college students solved geometric analogies requiring two or three transformations and indicated the order in which they performed the transformations. There was close agreement on nearly the same order for both types of analogies. In the second experiment, subjects were directed to perform pairs of transformations in the preferred or unpreferred order. Both speed and accuracy were greater for the preferred orders, thus validating subjects' reported orders. Ability differences were observed for only the more difficult three-transformation problems: High- and middle-ability subjects agreed on an overall performance order, but the highs were more consistent in their use of this order. Low-ability subjects did not consistently order the transformations for these difficult problems. The general information processing factor examined was working-memory load. A number of task factors have been shown to affect working-memory load during the solution of inductive reasoning problems. Of these, we chose to examine process difficulty. Because analogies are solved in working memory, performing more difficult transformations earlier may reduce working-memory load and facilitate problem solution. However, the observed performance order was not correlated with transformation difficulty. The first task-specific factor considered was that some transformations may be identified earlier, possibly because of perceptual salience, and that the performance order follows the identification order.(ABSTRACT TRUNCATED AT 400 WORDS)

Cognition↗
PubMed1984

Objects, parts, and categories.

Concepts may be organized into taxonomies varying in inclusiveness or abstraction, such as furniture, table, card table or animal, bird, robin. For taxonomies of common objects and organisms, the basic level, the level of table and bird, has been determined to be most informative (Rosch, Mervis, Gray, Johnson, & Boyes-Braem, 1976). Psychology, linguistics, and anthropology have produced a variety of measures of perception, behavior, and communication that converge on the basic level. Here, we present data showing that the basic level differs qualitatively from other levels in taxonomies of objects and of living things and present an explanation for why so many measures converge at that level. We have found that part terms proliferate in subjects' listings of attributes characterizing category members at the basic level, but are rarely listed at a general level. At a more specific level, fewer parts are listed, though more are judged to be true. Basic level objects are distinguished from one another by parts, but members of subordinate categories share parts and differ from one another on other attributes. Informants agree on the parts of objects, and also on relative "goodness" of the various parts. Perceptual salience and functional significance both appear to contribute to perceived part goodness. Names of parts frequently enjoy a duality not evident in names of other attributes; they refer at once to a particular appearance and to a particular function. We propose that part configuration underlies the various empirical operations of perception, behavior, and communication that converge at the basic level. Part configuration underlies the perceptual measures because it determines the shapes of objects to a large degree. Parts underlie the behavioral tasks because most of our behaviors is indirect toward parts of objects. Labeling appears to follow the natural breaks of perception and behavior; consequently, part configuration also underlies communication measures. Because elements of more abstract taxonomies, such as scenes and events, can also be decomposed into parts, this analysis provides a bridge to organization in other domains of knowledge. Knowledge organization by parts (partonomy) is contrasted to organization by kinds (taxonomy). Taxonomies serve to organize numerous classes of entities and to allow inference from larger sets to sets included in them. Partonomies serve to separate entities into their structural components and to organize knowledge of function by components of structure. The informativeness of the basic level may originate from the availability of inference from structure to function at that level.

Discrimination Learning↗
PubMed1984

Force of symmetry in form perception.

Many objects, natural and manufactured, have at least one axis of symmetry; thus, the detection of symmetry could facilitate the detection and representation of objects. Literature is reviewed that supports the notion that humans have effective and efficient symmetry-detection ability. The question addressed in the present research is whether symmetry detection leads to biases in representations of visual forms. Two types of experimental tasks were used: a similarity-judgment task and a matching-figures task in which reaction time to find identical figures in a display was measured. Stimuli varied in degree of measured symmetry. The results of the experiments reported here indicate that nearly symmetric standard forms are judged to be more similar to, and are more confusable with, even more symmetric forms than they are with less symmetric forms. The pull toward a more symmetric form does not occur for standard forms of lower symmetry. These findings can be accounted for by a two-stage process. First, the perceiver quickly determines the presence of overall symmetry. Then, if the form is perceived as having overall symmetry, the form is assumed, sometimes incorrectly, to have symmetry at the local level as well.

Discrimination Learning↗