Salience, relevance, and firing: a priority map for target selection

The salience map is a crucial concept for many theories of visual attention. On this map, each object in the scene competes for selection - the more conspicuous the object, the greater its representation, and the more likely it will be chosen. In recent years, the firing patterns of single neurons have been interpreted using this framework. Here, we review evidence showing that the expression of salience is remarkably similar across structures, remarkably different across tasks, and modified in important ways when the salient object is consistent with the goals of the participant. These observations have important ramifications for theories of attention. We conclude that priority--the combined representation of salience and relevance--best describes the firing properties of neurons.     

Profiling local optima in K-means clustering: developing a diagnostic technique

Using the cluster generation procedure proposed by D. Steinley and R. Henson (2005), the author investigated the performance of K-means clustering under the following scenarios: (a) different probabilities of cluster overlap; (b) different types of cluster overlap; (c) varying samples sizes, clusters, and dimensions; (d) different multivariate distributions of clusters; and (e) various multidimensional data structures. The results are evaluated in terms of the Hubert-Arabie adjusted Rand index, and several observations concerning the performance of K-means clustering are made. Finally, the article concludes with the proposal of a diagnostic technique indicating when the partitioning given by a K-means cluster analysis can be trusted. By combining the information from several observable characteristics of the data (number of clusters, number of variables, sample size, etc.) with the prevalence of unique local optima in several thousand implementations of the K-means algorithm, the author provides a method capable of guiding key data-analysis decisions.     

Differential prefrontal-temporal neural correlates of semantic processing in children

This study used functional magnetic resonance imaging (fMRI) to examine brain-behavior correlations in a group of 16 children (9- to 12-year-olds). Activation was measured during a semantic judgment task presented in either the visual or auditory modality that required the individual to determine whether a final word was related in meaning to one of two previous words (e.g., found-tank-lost). The main finding was that higher performers (i.e., accuracy) were associated with more activation in posterior representational systems including the inferior and middle temporal gyri, whereas lower performers were associated with more activation in anterior regions including the inferior and middle frontal gyri. This pattern of results was interpreted as reflecting an elaborated semantic representational system in temporal areas for the high accuracy performers that allowed them to efficiently and accurately make meaning based judgments. The low accuracy performers may have an inaccurate or weakly interconnected semantic system that results in greater use of frontal areas in a feature selection process.     

Observing Behavior Topography in Delayed Matching to Multiple Samples

The Psychological Record - This study examined relations between eye movements and accuracy scores in a delayed matching-to-sample procedure with multiple sample stimuli. Four adult humans...     

Orientation in cognitive maps

In 14 experiments, subjects had to “point to” surrounding environmental locations (targets) while imagining themselves in a particular spot facing in various directions (orientations). The spatial information was either committed to memory (cognitive maps) or directly presented on each trial in the visual or tactile modality. Reaction times (RT) indicated that orientation shifts were achieved through mental rotation in the visual task, but not in the cognitive map or tactile tasks. Further, in the latter two tasks targets were located most quickly when they were adjacent to or opposite the imagined orientation. Several explanations of this finding were tested. Various aspects of the data suggest that cognitive maps are not strictly holistic, but consist of orientation-specific representations, and—at least in part—of relational propositions specific to object pairs.     

Non‐standard work schedules and retention in the entry‐level hourly workforce

Non‐standard work schedules involve work outside the Monday–Friday daytime hours. Although research has heavily studied the health and family effects of such schedules, few studies have investigated their relationship to retention. We draw from Maertz and Campion's discussion of motivational forces that influence turnover to propose that employees on non‐standard schedules are more likely to quit their employer because of general job dissatisfaction and because of normative pressures from family and/or friends. Specifically, we hypothesized that employees on day shifts or weekday only schedules would remain with their employer longer than those who work on nonday shifts or on the weekends. We also hypothesized that perceived employment mobility would moderate the effects of non‐standard schedules on retention length. Hypotheses were tested among 3,178 retail employees who worked five different distinct shift arrangements and different weekday/weekend schedules. Cox regression analyses indicated that, as hypothesized, employees working nonday shifts or schedules including weekends remained with their employer for a shorter duration of time than employees not on such schedules. Perceived mobility moderated the schedule–turnover relationship, though not in the hypothesized manner. We discuss the theoretical and practical implications of these findings for work schedule assignment and retention strategies.     

Exploring the role of individual differences in the prediction of workplace aggression

This study investigates the relationship between individual differences and the incidence of workplace aggression in a sample of employees from a transportation company and a public school system. Hierarchical multiple regression analysis indicated that measures of trait anger, attribution style, negative affectivity, attitudes toward revenge, self-control, and previous exposure to aggressive cultures accounted for 62% of the variance in the participants' self-reported incidence of workplace aggression. Further research on workplace aggression is advocated, focusing on the role of individual differences and their interactions with organizational and group-level variables.     

Imperfect Reasons and Rational Options

Agents often face a choice of what to do. And it seems that, in most of these choice situations, the relevant reasons do not require performing some particular act, but instead permit performing any of numerous act alternatives. This is known as the basic belief. Below, I argue that the best explanation for the basic belief is not that the relevant reasons are incommensurable (Raz) or that their justifying strength exceeds the requiring strength of opposing reasons (Gert), but that they are imperfect reasons—reasons that do not support performing any particular act, but instead support choosing any of the numerous alternatives that would each achieve the same worthy end. In the process, I develop and defend a novel theory of objective rationality, arguing that it is superior to its two most notable rivals.