The use of diagrams in analogical problem solving.

In four experiments, we examined the impact of perceptual properties on the effectiveness of diagrams in analogical problem solving, using variants of convergence diagrams as source analogues for the radiation problem. Static diagrams representing the initial problematic state (one large line directed at a target) and the final state for a convergence solution (multiple converging lines) were not accessed spontaneously but were often used successfully once a hint to consider the diagram had been provided. The inaccessibility of static diagrams was not alleviated by adding additional diagrams to represent intermediate states (Experiment 1), but spontaneous access was improved by augmenting static diagrams with a verbal statement of the convergence principle (Experiment 3). Spontaneous retrieval and noticing were increased markedly by animating displays representing converging forces and thereby encouraging encoding of the lines as indicating motion toward a target (Experiments 3 and 4). However, neither static nor animated diagrams were effective when the arrows were reversed to imply divergence rather than convergence (Experiment 2). The results indicate that when animation encourages the interpretation of a diagram as a helpful source analogue, it can greatly enhance analogical transfer.

Connectedness and part-relation integration in shape category learning.

We investigated the role of connectedness in the use of part-relation conjunctions for object category learning. Participants learned categories of two-part objects defined by the shape of one part and its location relative to the other (part-relation conjunctions). The topological relationship between the parts (connected, separated, or embedded) varied between participants but was invariant for any given participant. In Experiment 1, category learning was faster and more accurate when an object's parts were connected than when they were either separated or embedded. Subsequent experiments showed that this effect is not due to conscious strategies, differences in the salience of the individual attributes, or differences in the integrality/separability of dimensions across stimuli. The results suggest that connectedness affects the integration of parts with their relations in object category learning.

The role of attention in priming for left-right reflections of object images: evidence for a dual representation of object shape.

Three experiments investigated the role of visual attention in priming for object images and their left-right reflections. Objects to which participants attended were visually primed in both the same view and in the left-right reflected view; ignored objects were primed only in the same view. The effects of attention (attended vs. ignored) and view (same vs. reflected) were strictly additive. These results suggest that 2 separate representations mediate human object recognition (J.E. Hummel & B.J. Stankiewicz, 1996): One requires attention but is invariant with left-right reflection, whereas the other can be activated automatically but is sensitive to left-right reflection. Both representations appear to be invariant with translation across the visual field.

Connectedness and the integration of parts with relations in shape perception.

Seven experiments investigated whether part connectedness would facilitate the perception of spatial relations among object parts. Experiments 1-4 showed that objects composed of connected parts are easier to distinguish from distractors in rapid serial visual presentation sequences than objects composed of separated parts and that this effect cannot be attributed to the presence of local features in the connected images. Experiments 5 and 6 revealed that image-based connectedness is neither necessary nor sufficient for the connectedness effect, and Experiment 7 showed that the connectedness effect is not a simple feature conjunction effect (i.e., it does not hold in a shape-color conjunction search task). These findings are consistent with the claim, central to the structural description theories, that the visual system not only decomposes objects into parts but also explicitly integrates those parts with their spatial relations.

Attribute conjunctions and the part configuration advantage in object category learning.

Five experiments demonstrated that in object category learning people are particularly sensitive to conjunctions of part shapes and relative locations. Participants learned categories defined by a part's shape and color (part-color conjunctions) or by a part's shape and its location relative to another part (part-location conjunctions). The statistical properties of the categories were identical across these conditions, as were the salience of color and relative location. Participants were better at classifying objects defined by part-location conjunctions than objects defined by part-color conjunctions. Subsequent experiments revealed that this effect was not due to the specific color manipulation or the role of location per se. These results suggest that the shape bias in object categorization is at least partly due to sensitivity to part-location conjunctions and suggest a new processing constraint on category learning.

Categorical relations in shape perception.

Many researchers have proposed that objects are perceived as structural descriptions, which specify the configuration of an object's features (or parts) in terms of their categorical relations to one another. Others have proposed that objects are perceived as views, which specify the configuration of an object's features in terms of their coordinates, in particular 2D views. This paper presents five experiments testing these competing accounts of the perception of the configuration of an object's features. Subjects learned to recognize a set of target objects and were tested for their ability to distinguish them from various distractors that differed either in their categorical relations or their coordinates. Subjects were consistently more likely to confuse both 2D and 3D objects that were similar in their parts' relations to each other than to confuse objects similar in their parts' coordinates (in any reference frame). This effect persisted when subjects were allowed to view the objects as long as they wished and when they were explicitly trained to distinguish them from the distractors. These findings suggest that we perceive an object's features in terms of their categorical relations to one another. A preliminary model of the findings is presented.

Dynamic binding in a neural network for shape recognition.

Given a single view of an object, humans can readily recognize that object from other views that preserve the parts in the original view. Empirical evidence suggests that this capacity reflects the activation of a viewpoint-invariant structural description specifying the object's parts and the relations among them. This article presents a neural network that generates such a description. Structural description is made possible through a solution to the dynamic binding problem: Temporary conjunctions of attributes (parts and relations) are represented by synchronized oscillatory activity among independent units representing those attributes. Specifically, the model uses synchrony (a) to parse images into their constituent parts, (b) to bind together the attributes of a part, and (c) to bind the relations to the parts to which they apply. Because it conjoins independent units temporarily, dynamic binding allows tremendous economy of representation and permits the representation to reflect the attribute structure of the shapes represented.

Metric invariance in object recognition: a review and further evidence.

Phenomenologically, human shape recognition appears to be invariant with changes of orientation in depth (up to parts occlusion), position in the visual field, and size. Recent versions of template theories (e.g., Ullman, 1989; Lowe, 1987) assume that these invariances are achieved through the application of transformations such as rotation, translation, and scaling of the image so that it can be matched metrically to a stored template. Presumably, such transformations would require time for their execution. We describe recent priming experiments in which the effects of a prior brief presentation of an image on its subsequent recognition are assessed. The results of these experiments indicate that the invariance is complete: The magnitude of visual priming (as distinct from name or basic level concept priming) is not affected by a change in position, size, orientation in depth, or the particular lines and vertices present in the image, as long as representations of the same components can be activated. An implemented seven layer neural network model (Hummel & Biederman, 1992) that captures these fundamental properties of human object recognition is described. Given a line drawing of an object, the model activates a viewpoint-invariant structural description of the object, specifying its parts and their interrelations. Visual priming is interpreted as a change in the connection weights for the activation of: a) cells, termed geon feature assemblies (GFAs), that conjoin the output of units that represent invariant, independent properties of a single geon and its relations (such as its type, aspect ratio, relations to other geons), or b) a change in the connection weights by which several GFAs activate a cell representing an object.

Causality and the allocation of attention during comprehension.

Recent research has suggested that each statement in a narrative text is understood by relating it to its causal antecedents and consequences and that the text as a whole is understood by finding a causal path linking its opening to its final outcome. Fletcher and Bloom (1988) have proposed that in order to accomplish this goal, while minimizing the number of times long-term memory has to be searched, readers focus their attention on the last clause of a narrative that has causal antecedents but no consequences in the preceding text. As a result, a statement that is followed by a causal antecedent should remain the focus of attention, while the same statement followed by a consequence should not. This prediction was tested and confirmed in three experiments which show that when a target statement is followed by a sentence that includes only causal antecedents, (a) continuation sentences related to it are read more quickly, (b) target words drawn from it are easier to recognize, and (c) subject-generated continuations are more likely to be causally related to it.