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To explore questions of how human infants begin to perceive partly occluded objects, we devised two connectionist models of perceptual development. The models were endowed with an existing ability to detect several kinds of visual information that have been found important in infants' and adults' perception of object unity (motion, co‐motion, common motion, relatability, parallelism, texture and T‐junctions). They were then presented with stimuli consisting of either one or two objects and an occluding screen. The models' task was to determine whether the object or objects were joined when such a percept was ambiguous, after specified amounts of training with events in which a subset of possible visual information was provided. The model that was trained in an enriched environment achieved superior levels of performance and was able to generalize veridical percepts to a wide range of novel stimuli. Implications for perceptual development in humans, current theories of development and origins of knowledge are discussed.

This study examined the relationship between listening effectiveness and leadership emergence in the task-oriented small group. Subjects were 51 undergraduate students in lO classroom groups assigned as zero-history, leaderless work groups. The groups met together for 12 weeks prior to participating in the study. Groups were videotaped conducting a decisionmaking discussion, and members later completed a recall instrument, a listeningperceptions instrument, and a leadership-perceptions instrument. Three sets of coders viewed the taped discussions and coded listening effectiveness, leadership behavior, and recall. Results show strong, positive relationships among all variables except recall, indicating that emergent leaders typically display more effective listening skills than the other members.

This study examined the perceptions of members of 23 task-oriented classroom small groups regarding the variables of leadership and listening. Following the completion of a long-term class assignment, groups were divided in half Half of each group completed a leadership assessment instrument while the other half completed a listening assessment instrument. Spearman correlations were computed on the data gathered. Results indicate a significant positive correlation between member rankings of leadership behavior and member rankings of listening effectiveness.

AbstractThis article reviews an analysis performed for a "high‐tech" company in mid‐1998 to evaluate the potential impacts of Y2K on the company's performance. The authors are no longer directly associated with the company and the results have been restated to protect the company's identity. The model performed better than existing in‐house tools, but inconsistency tests uncovered "insider" information that needed to be included in the model. The final scenarios and associated recommendations indicated response requirements incompatible with the time constants of information flows within the company. Like the Titanic moving toward the iceberg, it was already too late for the company to do much more than hope that fate would be kind. The causal dynamics left little to fate. A "validated" model often becomes part of the problem and the feedback (decision‐making) system it is attempting to influence. To have a successful impact, consultants may need to give up their supposed objective position and personally engage themselves in the risk‐ridden, internal, political processes of the client organization. Copyright © 2001 John Wiley & Sons, Ltd.

Necrotizing fasciitis is a rapidly spreading, life‐threatening, bacterial disease. Mortality rates have been estimated to vary between 8.7% and 74%. Mortality depends on many factors, one of which Is early recognition. Necrotizing fasciitis of dental origin has a low prevalence and as such presents diagnostic challenges for the dentist. The literature is reviewed, and a case history Is presented.