An Overview of Possibilistic Handling of Default Reasoning, with Experimental Studies

This paper first provides a brief survey of a possibilistic handling of default rules. A set of default rules of the form, “generally, from α deduce β”, is viewed as the family of possibility distributions satisfying constraints expressing that the situation where α and β is true has a greater plausibility than the one where a and - β is true. When considering only the subset of linear possibility distributions, the well-known System P of postulates proposed by Kraus, Lehmann and Magidor, has been obtained. We also present two rational extensions: one based on the minimum specificity principle and the other is based on the lexicographic ordering. The second part of the paper presents an empirical study of three desirable properties for a consequence relation that capture default reasoning: Rationality, Property Inheritance and Ambiguity Preservation. An experiment is conducted to investigate 13 patterns of inference for the test of these properties. Our experimental apparatus confirms previous results on the relevance of System P, and enforces the psychological relevance of the studied properties.     

Handling Locally Stratified Inconsistent Knowledge Bases

This paper investigates the idea of reasoning, in a local (or contextual) way, under prioritized and possibly inconsistent knowledge bases. Priorities are not supposed to be given globally between all the beliefs in the knowledge base, but locally inside sets of pieces of information responsible for inconsistencies. This local stratification offers more flexibility for representing priorities between beliefs. Given this local ordering, we discuss five basic definitions of influence relations between conflicts. These elementary notions of influence between two conflicts A and B exhaustively explore the situations where solving A leads to solve B. Then we propose natural approaches to restore the coherence of a knowledge base on the basis of influence relations between locally-stratified conflicts.     

Some Syntactic Approaches to the Handling of Inconsistent Knowledge Bases: A Comparative Study Part 1: The Flat Case

This paper presents and discusses several methods for reasoning from inconsistent knowledge bases. A so-called argued consequence relation, taking into account the existence of consistent arguments in favour of a conclusion and the absence of consistent arguments in favour of its contrary, is particularly investigated. Flat knowledge bases, i.e., without any priority between their elements, are studied under different inconsistency-tolerant consequence relations, namely the so-called argumentative, free, universal, existential, cardinality-based, and paraconsistent consequence relations. The syntax-sensitivity of these consequence relations is studied. A companion paper is devoted to the case where priorities exist between the pieces of information in the knowledge base.     

Musicians' working memory for tones, words, and pseudowords

Studies investigating factors that influence tone recognition generally use recognition tests, whereas the majority of the studies on verbal material use self-generated responses in the form of serial recall tests. In the present study we intended to investigate whether tonal and verbal materials share the same cognitive mechanisms, by presenting an experimental instrument that evaluates short-term and working memories for tones, using self-generated sung responses that may be compared to verbal tests. This paradigm was designed according to the same structure of the forward and backward digit span tests, but using digits, pseudowords, and tones as stimuli. The profile of amateur singers and professional singers in these tests was compared in forward and backward digit, pseudoword, tone, and contour spans. In addition, an absolute pitch experimental group was included, in order to observe the possible use of verbal labels in tone memorization tasks. In general, we observed that musical schooling has a slight positive influence on the recall of tones, as opposed to verbal material, which is not influenced by musical schooling. Furthermore, the ability to reproduce melodic contours (up and down patterns) is generally higher than the ability to reproduce exact tone sequences. However, backward spans were lower than forward spans for all stimuli (digits, pseudowords, tones, contour). Curiously, backward spans were disproportionately lower for tones than for verbal material-that is, the requirement to recall sequences in backward rather than forward order seems to differentially affect tonal stimuli. This difference does not vary according to musical expertise.     

The Effect of Professional Partnership on the Development of a Mutual-help Organization

The effects of partnership between Schizophrenics Anonymous (SA, a mutual-help organization) and the Mental Health Association in Michigan (MHAM, a professionally staffed advocacy organization) on SA's growth and development were explored. Following the initiation of a formal partnership, SA groups were more available throughout the state, more likely to be associated with formal mental health settings, and less likely to have leaders who had been participants in other SA groups. Groups with consumer leaders had significantly greater longevity than groups with professional leaders. Changes in the organizational structure and process of SA were also identified. SA leaders reported that SA moved from a collective to a more bureaucratic structure. As a result, there was greater consistency, administrative capacity, and response capacity. This enhanced capacity came with costs reported by SA leaders. The leadership role of SA members became less defined. SA members expressed concerns about the more hierarchical structure of SA's organization, decreased consumer control, increased professional involvement in SA, and an excessive focus on group development as opposed to group maintenance. Mental Health Association in Michigan staff reported that MHAM was also impacted by the partnership, both with regard to internal functioning and external perception. Implications for effective partnerships between mutual-help and professional organizations are discussed.     

A Practical Approach to Revising Prioritized Knowledge Bases

This paper investigates simple syntactic methods for revising prioritized belief bases, that are semantically meaningful in the frameworks of possibility theory and of Spohn's ordinal conditional functions. Here, revising prioritized belief bases amounts to conditioning a distribution function on interpretations. The input information leading to the revision of a knowledge base can be sure or uncertain. Different types of scales for priorities are allowed: finite vs. infinite, numerical vs. ordinal. Syntactic revision is envisaged here as a process which transforms a prioritized belief bases into a new prioritized belief base, and thus allows a subsequent iteration.     

Facilitating Interorganizational Collaboration: The Contributions of Interorganizational Alliances

In an attempt to promote service delivery integration and improve interorganizational collaboration, many recent human service delivery initiatives have included the development of interorganizational alliances such as coalitions and coordinating councils. Despite their popularity, little is known about how these alliances influence interorganizational collaboration, specifically the extent to which they alter the interactions among human service delivery organizations. The present study examined the interorganizational interactions, specifically the exchange relationships, within one county that was implementing two interorganizational alliances—a countywide coordinating council and interagency service delivery teams. Membership on both alliances was associated with broader interorganizational exchange networks. Organizations involved in a coordinating council were more likely to be included in client, information, and resource exchanges, and participate in joint ventures with a broader range of organizations. Providers involved in interagency teams also exchanged clients and information with a broader sector of service delivery organizations than nonparticipating providers. Observational data suggested that both alliances created structures and processes intended to facilitate interorganizational exchanges. Together, these results suggest that the development of opportunities for and encouragement of staff and leader involvement in these types of alliances may be an important part of our attempt to create a more integrated social service delivery system. The implications of these findings for researchers and practitioners are discussed.     

Combined behavioural markers of cognitive biases are associated with anhedonia

Biases towards negative information, as well as away from positive information, are associated with psychopathology. Examining biases in multiple processes has been theorised to be more predictive than examining bias in any process alone. Anhedonia is a core symptom of psychopathology and predictive of future psychopathological symptoms. Finding that combined biases are associated with anhedonia would advance knowledge of the nature of emotional processing biases and the value of objective performance-based measures for identifying early risk markers. Participants (N?=?139) completed tasks that assess latency bias (dot probe) and biased recognition (two-alternative forced-choice) of emotional information, as well as an anhedonia measure. An index was computed for each task’s performance reflecting biased processing of positive and negative words. Only combined biases on both tasks were associated with anhedonia. Attentional bias was positively associated with anhedonia, but only when recognition bias for emotional words was high. Thus, assessing biases in multiple domains increased sensitivity to uncover relationships between emotional processing biases and anhedonic symptoms.