Rectilinear steiner tree heuristics and minimum spanning tree algorithms using geographic nearest neighbors

We study the application of the geographic nearest neighbor approach to two problems. The first problem is the construction of an approximately minimum length rectilinear Steiner tree for a set ofn points in the plane. For this problem, we introduce a variation of a subgraph of sizeO(n) used by YaO [31] for constructing minimum spanning trees. Using this subgraph, we improve the running times of the heuristics discussed by Bern [6] fromO(n ² log n) toO(n log² n). The second problem is the construction of a rectilinear minimum spanning tree for a set ofn noncrossing line segments in the plane. We present an optimalO(n logn) algorithm for this problem. The rectilinear minimum spanning tree for a set of points can thus be computed optimally without using the Voronoi diagram. This algorithm can also be extended to obtain a rectilinear minimum spanning tree for a set of nonintersecting simple polygons.The results in this paper are a part of Y. C. Yee's Ph.D. thesis done at SUNY at Albany. He was supported in part by NSF Grants IRI-8703430 and CCR-8805782. S. S. Ravi was supported in part by NSF Grants DCI-86-03318 and CCR-89-05296.     

"Eating lightly" and the self-presentation of femininity.

In Experiment 1, male and female subjects were given an opportunity to snack as they participated in a "get-acquainted study" with a same-sex or opposite-sex partner (confederate) whose social desirability was manipulated. Consistent with the hypothesis that women may eat less when motivated to present themselves in a feminine light, female subjects ate significantly less with a desirable male partner than in the remaining three conditions. In contrast, male subjects did not eat more (or less) with a desirable woman, although they did show an overall tendency to eat less with female (vs. male) partners. In Experiment 2, female subjects snacked as they got acquainted with a desirable male partner (confederate). Before this interaction, subjects received feedback indicating that they had either very masculine or very feminine interests. In addition, subjects believed either that their male partner was aware of their gender feedback or that he was unaware. Consistent with predictions derived from Schlenker's (1982) analytic-identity theory of social conduct, subjects in the partner-aware conditions ate less when they had received masculine (vs. feminine) feedback, whereas subjects in the partner-unaware conditions ate less when they had received feminine (vs. masculine) feedback. Implications for understanding eating disorders such as anorexia and bulimia are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Percentage discounts, initial price, and bargain hunting: A heuristic-systematic approach to price search behavior.

Consumer decisions concerning price search were investigated using the heuristic-systematic model of social judgment (S. Chaiken, A. Liberman, & A. H. Eagly, 1989). Consumers used the size of the percentage discount as a heuristic cue to help decide whether a better price was likely to be available elsewhere. However, as predicted, participants relied on this cue only when the initial base price of the item was low. In contrast, search was continued despite the offer of a large percentage discount when consumers were shopping for items that were relatively expensive. This finding was attributed to the higher potential costs associated with missing a better price when consumers were shopping for more expensive items. In general, the heuristic-systematic model proved to be a useful way to characterize price search decisions. It was also suggested that these findings might be useful in explaining some conflicting results in the price search literature. Implications for behavioral price theories are also discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attitude strength and resistance processes.

This study examined whether multiple indicators of attitude strength form general dimensions that foster differential pathways to resistance. Ego involvement, certainty, personal importance, knowledge, and extremity were assessed. Resistance processes and outcomes were measured in a selective judgment paradigm. Intentions to act on attitudes and information-seeking proclivities were also assessed. Factor analyses of the strength measures revealed 2 factors. Both fostered intentions to act but were associated with differential resistance processes and outcomes. Heightened levels of the factor representing commitment to one's position were associated with increased selective elaboration, selective judgment, and attitude polarization. Embeddedness, the linkage of the attitude to one's self-concept, value system, and knowledge structure, was associated with decreased selective elaboration and increased information seeking and selective memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Causal inferences about communicators and their effect on opinion change.

An attribution analysis of opinion change viewed message persuasiveness as a function of inferred communicator biases. Recipients infer a knowledge bias (KB) by believing that a communicator's knowledge about external reality is nonveridical and a reporting bias (RB) by believing that a communicator's willingness to convey an accurate version of external reality is compromised. In an experiment with 355 undergraduates, KB expectancies were established by portraying a communicator as having a strong commitment to values represented by the probusiness or proenvironment side of a controversial issue and RB expectancies by portraying his audience as having a strong commitment to one or the other side. In all conditions, the communicator advocated the proenvironment position. Therefore, recipients' expectancies were confirmed in the context of a proenvironment communicator and/or audience and disconfirmed in the context of a probusiness communicator and/or audience. Regardless of the type of bias that Ss expected, they were more persuaded and rated the communicator as more unbiased when their expectancies were disconfirmed. Confirmation of expectancies based on RB, but not KB, was associated with inferences of communicator insincerity and manipulativeness. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Heuristic versus systematic information processing and the use of source versus message cues in persuasion.

In Exp I, 183 undergraduates read a persuasive message from a likable or unlikable communicator who presented 6 or 2 arguments on 1 of 2 topics. High involvement (HI) Ss anticipated discussing the message topic at a future experimental session, whereas low-involvement (LI) Ss anticipated discussing a different topic. For HI Ss, opinion change was significantly greater given 6 arguments but was unaffected by communicator likability. For LI Ss, opinion change was significantly greater given a likable communicator but was unaffected by the argument's manipulation. In Exp II with 80 similar Ss, HI Ss showed slightly greater opinion change when exposed to 5 arguments from an unlikable (vs 1 argument from a likable) communicator, whereas LI Ss exhibited significantly greater persuasion in response to 1 argument from a likable (vs 5 arguments from an unlikable) communicator. Findings support the idea that HI leads message recipients to employ a systematic information processing strategy in which message-based cognitions mediate persuasion, whereas LI leads recipients to use a heuristic processing strategy in which simple decision rules mediate persuasion. Support was also obtained for the hypothesis that content- vs source-mediated opinion change would result in greater persistence. (37 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Communicator physical attractiveness and persuasion.

In a field setting, each of 68 physically attractive or unattractive male and female communicator Ss (undergraduates) delivered a persuasive message to 2 undergraduate target Ss of each sex. Results indicate that attractive (vs unattractive) communicators induced significantly greater persuasion on both a verbal and behavioral measure of target agreement. In addition, female targets indicated greater agreement than male targets. Data gathered from communicator Ss during an earlier laboratory session indicate that physically attractive and unattractive communicators differed with respect to several communication skills and other attributes relevant to communicator persuasiveness, including GPA, Scholastic Aptitude Test scores, and several measures of self-evaluation. These findings suggest that attractive individuals may be more persuasive than unattractive persons partly because they possess characteristics that dispose them to be more effective communicators. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)