A biologically based model for recognition of 2-D occluded patterns

In this work, we present a biologically inspired model for recognition of occluded patterns. The general architecture of the model is based on the two visual information processing pathways of the human visual system, i.e. the ventral and the dorsal pathways. The proposed hierarchically structured model consists of three parallel processing channels. The main channel learns invariant representations of the input patterns and is responsible for pattern recognition task. But, it is limited to process one pattern at a time. The direct channel represents the biologically based direct connection from the lower to the higher processing level in the human visual cortex. It computes rapid top-down pattern-specific cues to modulate processing in the other two channels. The spatial channel mimics the dorsal pathway of the visual cortex. It generates a combined saliency map of the input patterns and, later, segments the part of the map representing the occluded pattern. This segmentation process is based on our hypothesis that the dorsal pathway, in addition to encoding spatial properties, encodes the shape representations of the patterns as well. The lateral interaction between the main and the spatial channels at appropriate processing levels and top-down, pattern-specific modulation of the these two channels by the direct channel strengthen the locations and features representing the occluded pattern. Consequently, occluded patterns become focus of attention in the ventral channel and also the pattern selected for further processing along this channel for final recognition.     

Hand mental rotation is not systematically altered by actual body position: Laterality judgment versus same–different comparison tasks

It is commonly believed that during mental rotation of body parts, participants tend to imagine their own body part moving toward the stimulus, thus using an egocentric strategy. Several studies have also shown that the mental rotation of hands is affected by the actual hand position, especially if the hand is kept in an awkward position. However, this hand posture effect, as well as the use of an egocentric strategy during mental rotation of body parts, is not systematic. Several experiments have demonstrated that manipulating the stimulus features or the paradigm could induce a shift to visual and allocentric strategies. Here, we studied the effects of hand posture and biomechanical constraints on one-hand mental rotation (laterality judgment task), two-hand mental rotation (same–different judgment task), and mental rotation of one or two alphanumeric symbols (control tasks). Effects of posture and biomechanical constraints were observed solely for the laterality judgment task. Response times in the same–different hand mental rotation items were influenced by the angular disparity between the stimuli. We interpreted our result as evidence of the use of different strategies for each task. Future research should focus on disentangling the exact subprocesses in which an egocentric strategy is used, in order to propose better tests for participants with motor impairments.     

Search through complex motion displays does not break down under spatial memory load

Recent work has shown that observers are remarkably effective in searching displays of randomly moving items. In two experiments, we combined working memory tasks with visual search, to test whether search through such complex motion displays, as compared with search through static items, places an extra burden on spatial working memory. In our first experiment, we show that the dual-task interference observed for motion search is specific to spatial working memory, in line with earlier work for static search. In our second experiment, we found dual-task interference for both static and motion search, but no difference between them. The results support the suggestion that the same search process is active during search among static and search among moving items.     

Touching on face space: Comparing visual and haptic processing of face shapes

The idea that faces are represented within a structured face space (Valentine Quarterly Journal of Experimental Psychology 43: 161–204, 1991) has gained considerable experimental support, from both physiological and perceptual studies. Recent work has also shown that faces can even be recognized haptically—that is, from touch alone. Although some evidence favors congruent processing strategies in the visual and haptic processing of faces, the question of how similar the two modalities are in terms of face processing remains open. Here, this question was addressed by asking whether there is evidence for a haptic face space, and if so, how it compares to visual face space. For this, a physical face space was created, consisting of six laser-scanned individual faces, their morphed average, 50 %-morphs between two individual faces, as well as 50 %-morphs of the individual faces with the average, resulting in a set of 19 faces. Participants then rated either the visual or haptic pairwise similarity of the tangible 3-D face shapes. Multidimensional scaling analyses showed that both modalities extracted perceptual spaces that conformed to critical predictions of the face space framework, hence providing support for similar processing of complex face shapes in haptics and vision. Despite the overall similarities, however, systematic differences also emerged between the visual and haptic data. These differences are discussed in the context of face processing and complex-shape processing in vision and haptics.     

Preferential Semantics using Non-smooth Preference Relations

This paper studies the properties of eight semantic consequence relations defined from a Tarski-logic L and a preference relation ? . They are equivalent to Shoham’s so-called preferential entailment for smooth model structures, but avoid certain problems of the latter in non-smooth configurations. Each of the logics can be characterized in terms of what we call multi-selection semantics. After discussing this type of semantics, we focus on some concrete proposals from the literature, checking a number of meta-theoretic properties and elaborating on their intuitive motivation. As it turns out, many of their meta-properties only hold in case ? is transitive. To tackle this problem, we propose slight modifications of each of the systems, showing the resulting logics to behave better at the intuitive level and in metatheoretic terms, for arbitrary ? .     

Spectral Decompositions of Multiple Time Series: A Bayesian Non-parametric Approach

We consider spectral decompositions of multiple time series that arise in studies where the interest lies in assessing the influence of two or more factors. We write the spectral density of each time series as a sum of the spectral densities associated to the different levels of the factors. We then use Whittle’s approximation to the likelihood function and follow a Bayesian non-parametric approach to obtain posterior inference on the spectral densities based on Bernstein–Dirichlet prior distributions. The prior is strategically important as it carries identifiability conditions for the models and allows us to quantify our degree of confidence in such conditions. A Markov chain Monte Carlo (MCMC) algorithm for posterior inference within this class of frequency-domain models is presented. We illustrate the approach by analyzing simulated and real data via spectral one-way and two-way models. In particular, we present an analysis of functional magnetic resonance imaging (fMRI) brain responses measured in individuals who participated in a designed experiment to study pain perception in humans.     

Probability Propagation in Generalized Inference Forms

Probabilistic inference forms lead from point probabilities of the premises to interval probabilities of the conclusion. The probabilistic version of Modus Ponens, for example, licenses the inference from \({P(A) = \alpha}\) and \({P(B|A) = \beta}\) to \({P(B)\in [\alpha\beta, \alpha\beta + 1 - \alpha]}\) . We study generalized inference forms with three or more premises. The generalized Modus Ponens, for example, leads from \({P(A_{1}) = \alpha_{1}, \ldots, P(A_{n})= \alpha_{n}}\) and \({P(B|A_{1} \wedge \cdots \wedge A_{n}) = \beta}\) to an according interval for P(B). We present the probability intervals for the conclusions of the generalized versions of Cut, Cautious Monotonicity, Modus Tollens, Bayes’ Theorem, and some SYSTEM O rules. Recently, Gilio has shown that generalized inference forms “degrade”—more premises lead to less precise conclusions, i.e., to wider probability intervals of the conclusion. We also study Adam’s probability preservation properties in generalized inference forms. Special attention is devoted to zero probabilities of the conditioning events. These zero probabilities often lead to different intervals in the coherence and the Kolmogorov approach.     

Structural Inference from Conditional Knowledge Bases

There are several approaches implementing reasoning based on conditional knowledge bases, one of the most popular being System Z (Pearl, Proceedings of the 3rd conference on theoretical aspects of reasoning about knowledge, TARK ’90, Morgan Kaufmann Publishers Inc., San Francisco, CA, USA, pp. 121–135, 1990). We look at ranking functions (Spohn, The Laws of Belief: Ranking Theory and Its Philosophical Applications, Oxford University Press, Oxford, 2012) in general, conditional structures and c-representations (Kern-Isberner, Conditionals in Nonmonotonic Reasoning and Belief Revision: Considering Conditionals as Agents, vol. 2087 of LNCS, Springer, Berlin, 2001) in order to examine the reasoning strength of the different approaches by learning which of the known calculi of nonmonotonic reasoning (System P and R) and Direct Inference are applicable to these inference relations. Furthermore we use the recently proposed Enforcement-postulate (Kern-Isberner and Krümpelmann, Proceedings of the 22nd international joint conference on artificial intelligence, vol. 2, IJCAI’11, AAAI Press, pp. 937–942, 2011) to show dependencies between these approaches.     

Structuring for team success: The interactive effects of network structure and cultural diversity on team potency and performance

This longitudinal study used data from 91 self-managed teams (456 individuals, 60 nationalities) to examine the interactive effects of a team’s task (“workflow”) network structure and its cultural diversity (as indexed by nationality) on the team’s “potency” (i.e., the team’s confidence in its ability to perform) and its performance (as rated by expert judges). We found that whereas the emergence of dense task networks enhanced team potency it was the emergence of (moderately) centralized task networks that facilitated team performance. These varied structural effects, moreover, were themselves contingent on team composition: the more culturally diverse a team, the more pronounced were the positive effects of network density on team potency and the higher the level of network centralization required for optimal team performance. The success of a team appears to hinge on the interplay between network structure and team composition.     

A Description–Experience Gap in Social Interactions: Information about Interdependence and Its Effects on Cooperation

In social interactions, decision makers are often unaware of their interdependence with others, precluding the realization of shared long‐term benefits. In an experiment, pairs of participants played an Iterated Prisoner's Dilemma under various conditions involving differing levels of interdependence information. Each pair was assigned to one of four conditions: “No‐Info” players saw their own actions and outcomes, but were not told that they interacted with another person; “Min‐Info” players knew they interacted with another person but still without seeing the other's actions or outcomes; “Mid‐Info” players discovered the other's actions and outcomes as they were revealed over time; and “Max‐Info” players were also shown a complete payoff matrix mapping actions to outcomes from the outset and throughout the game. With higher levels of interdependence information, we found increased individual cooperation and mutual cooperation, driven by increased reciprocating cooperation (in response to a counterpart's cooperation). Furthermore, joint performance and satisfaction were higher for pairs with more information. We discuss how awareness of interdependence may encourage cooperative behavior in real‐world interactions. Copyright © 2013 John Wiley & Sons, Ltd.