Analogies are typically drawn from a well-understood situation to a situation that is poorly understood. In this research, we investigate a different route to analogical insight. We suggest that mutual alignment-that is, comparison between 2 partially understood situations-can act to promote comprehension and abstraction. We presented participants with 2 analogous scenarios depicting heat flow. They were given processing tasks that varied in the degree to which comparison was required. We then measured insight into the common structure in 3 ways. Participants were asked to (a) specify differences between the 2 pictured scenarios, (b) write scenario descriptions, and (c) rate the similarity of the 2 scenarios. The results show that carrying out comparison promotes greater insight into the common causal structure, but only when the comparison is intensive. The best results were obtained when participants were asked to jointly interpret the scenarios and to list specific correspondences. In a second experiment designed to further pinpoint the source of the comparison advantage, participants were asked to make correspondences between the elements of the 2 scenarios. These results suggest that mutual alignment is an effective means of promoting insight.The ability to think analogically is central to human cognition. Progress in scientific and technological domains often arises from the discovery of a profound analogy such as the planetary model of atomic structure, the water flow analogy of heat transfer, and the computer metaphor of the human mind (Gentner et al.suggested, on the basis of his studies of the behavior of scientists in real-world microbiology laboratories, that analogy use is positively correlated with successful scientific investigation.Research on analogical processing and case-based reasoning shows the importance of analogy in learning and understanding (

This chapter is concerned with the acquisition and use of relational categories. By relational category, we mean a category whose membership is determined by a common relational structure rather than by common properties. For instance, for X to be a bridge, X must connect two other entities or points; for X to be a carnivore, X must eat animals. Relational categories contrast with entity categories such as tulip or camel, whose members share many intrinsic properties. Relational categories cohere on the basis of a core relationship fulfilled by all members. This relation may be situation-specific (e.g.,passenger or accident} or enduring (e.g., carnivore or ratio). Relational categories abound in ordinary language. Some are restricted in their arguments: For example, carnivores are animals who eat other animals. But for many relational categories, the arguments can range widely: for example, a bridge can connect two concrete locations, or two generations, or two abstract ideas. As with bridge, the instances of a relational category can have few or no intrinsic properties in common with one another.Research on categories has mostly ignored relational categories, focusing instead on entity categories-categories that can be characterized in terms of intrinsic similarity among members, like those shown in Figure 9.1. Further, as Kloos and Sloutsky ( 2004) point out, theories of categorization have often operated under the assumption that all concepts are fundamentally alike. However, as Medin and his colleagues (Medin, Lynch, & Coley, 1997;Medin, Lynch, & Solomon, 2000) have argued, categories are not uniform in character, and the variations support a range of different functions. In this chapter, we contrast relational categories-categories whose members satisfy a specified relational This research was supported by NSF grant SBR-95-11757 and ONR contract N00014-92-J-1098 to Dedre Gentner, and by NSF-ROLE award 21002/REC-0087516. We thank Jennifer Asmuth, Jeff Loewenstein, Art Markman, and Phillip Wolff for discussions of these issues, and Jason Jameson, Brad Love, and Vladimir Sloutsky for insightful comments on this paper. Most of all, we thank Doug Medin for many delightful discussions and much inspiration.

Three experiments were performed to examine the role that central and peripheral vision play in the perception of the direction of translational self-motion, or heading, from optical flow. When the focus of radial outflow was in central vision, heading accuracy was slightly higher with central circular displays (10°-25°diameter) than with peripheral annular displays (40°diameter), indicating that central vision is somewhat more sensitive to this information. Performance dropped rapidly as the eccentricity of the focus of outflow increased, indicating that the periphery does not accurately extract radial flow patterns. Together with recent research on vection and postural adjustments, these results contradict the peripheral dominance hypothesis that peripheral vision is specialized for perception of self-motion. We propose a functional sensitivity hypothesis-thai. self-motion is perceived on the basis of optical information rather than the retinal locus of stimulation, but that central and peripheral vision are differentially sensitive to the information characteristic of each retinal region.Research on the role of vision in the perception of selfmotion has emphasized three phenomena induced by optical flow stimulation: (1) vection, or the subjective experience of self-motion; (2) postural adjustments such as body sway or tilt during standing; and (3) the perception of heading, or the direction of self-motion. To some extent, these phenomena are independent of one another, for vection and heading are commonly perceived without postural adjustments, heading can be perceived without the sensation of vection, and postural compensation has been reported with optical velocities too low to induce vection (Delorme & Martin, 1986;Lee & Lishman, 1975;Stoffregen, 1986). However, to the extent that vection is experienced in a definite direction and postural adjustments are directionally specific, the extraction of information about heading is implicated.On the basis of evidence from the first two domains, claims have frequently been made for a peripheral dominance hypothesis-specifically, that peripheral vision plays the dominant role in the perception and control of selfmotion and that central vision is relatively insensitive to such information. In their review, Dichgans and Brandt (1978) concluded that, "The peripheral retina dominates visually induced vection and spatial orientation, whereas central vision dominates pattern perception and object motion detection" (p. 777; italics in original). Our purpose in the present paper is to consider the role ofdifferent retinal regions in perceiving self-motion and to include a review

No abstract

All models of self-motion from optical flow assume the instantaneous velocity field as input. We tested this assumption for human observers using random-dot displays that simulated translational and circular paths of movement by manipulating the lifetime and displacement of individual dots. For translational movement, observers were equally accurate in judging direction of heading from a "velocity field" with a two-frame dot life and a "direction field" in which the magnitudes of displacement were randomized while the radial pattern of directions was preserved, but at chance with a "speed field" in which the directions were randomized, preserving only magnitude. Accuracy declined with increasing noise in vector directions, but remained below 2.6 degrees with a 90 degrees noise envelope. Thus, the visual system uses the radial morphology of vector directions to determine translational heading and can tolerate large amounts of noise in this pattern. For circular movement, observers were equally accurate with a 2-frame "velocity field", 3-frame "acceleration" displays, and 2-frame and 3-frame "direction fields", consistent with the use of the pattern of vector directions to locate the center of rotation. The results indicate that successive independent velocity fields are sufficient for perception of translational and circular heading.

The findings of Shepard, Hovland, and Jenkins (1961) on the relative ease of learning 6 elemental types of 2-way classifications have been deeply influential 2 times over: 1st, as a rebuke to pure stimulus generalization accounts, and again as the leading benchmark for evaluating formal models of human category learning. The litmus test for models is the ability to simulate an observed advantage in learning a category structure based on an exclusive-or (XOR) rule over 2 relevant dimensions (Type II) relative to category structures that have no perfectly predictive cue or cue combination (including the linearly-separable Type IV). However, a review of the literature reveals that a Type II advantage over Type IV is found only under highly specific experimental conditions. We investigate when and why a Type II advantage exists to determine the appropriate benchmark for models and the psychological theories they represent. A series of 8 experiments link particular conditions of learning to outcomes ranging from a traditional Type II advantage to compelling non-differences and reversals (i.e., Type IV advantage). Common interpretations of the Type II advantage as either a broad-based phenomenon of human learning or as strong evidence for an attention-mediated similarity-based account are called into question by our findings. Finally, a role for verbalization in the category learning process is supported.

This research addresses the kinds of matching elements that determine analogical relatedness and literal similarity. Despite theoretical agreement on the importance of relational match, the empirical evidence is neither systematic nor definitive. In 3 studies, participants performed online evaluations of relatedness of sentence pairs that varied in either the object or relational match. Results show a consistent focus on relational matches as the main determinant of analogical acceptance. In addition, analogy does not require strict overall identity of relational concepts. Semantically overlapping but nonsynonymous relations were commonly accepted, but required more processing time. Finally, performance in a similarity rating task partly paralleled analogical acceptance; however, relatively more weight was given to object matches. Implications for psychological theories of analogy and similarity are addressed.

No abstract