The role of response mechanisms in determining reaction time performance: Piéron’s Law revisited

A response mechanism takes evaluations of the importance of potential actions and selects the most suitable. Response mechanism function is a nontrivial problem that has not received the attention it deserves within cognitive psychology. In this article, we make a case for the importance of considering response mechanism function as a constraint on cognitive processes and emphasized links with the wider problem of behavioral action selection. First, we show that, contrary to previous suggestions, a well–known model of the Stroop task (Cohen, Dunbar, & McClelland, 1990) relies on the response mechanism for a key feature of its results—the interference–facilitation asymmetry. Second, we examine a variety of response mechanisms (including that in the model of Cohen et al., 1990) and show that they all follow a law analogous to Piéron's law in relating their input to reaction time. In particular, this is true of a decision mechanism not designed to explain RT data but based on a proposed solution to the general problem of action selection and grounded in the neurobiology of the vertebrate basal ganglia. Finally, we show that the dynamics of simple artificial neurons also support a Piéron–like law

On Properties of Policy-Based Specifications

The advent of large-scale, complex computing systems has dramatically increased the difficulties of securing accesses to systems' resources. To ensure confidentiality and integrity, the exploitation of access control mechanisms has thus become a crucial issue in the design of modern computing systems. Among the different access control approaches proposed in the last decades, the policy-based one permits to capture, by resorting to the concept of attribute, all systems' security-relevant information and to be, at the same time, sufficiently flexible and expressive to represent the other approaches. In this paper, we move a step further to understand the effectiveness of policy-based specifications by studying how they permit to enforce traditional security properties. To support system designers in developing and maintaining policy-based specifications, we formalise also some relevant properties regarding the structure of policies. By means of a case study from the banking domain, we present real instances of such properties and outline an approach towards their automatised verification.Comment: In Proceedings WWV 2015, arXiv:1508.0338

Compositional Verification for Timed Systems Based on Automatic Invariant Generation

We propose a method for compositional verification to address the state space explosion problem inherent to model-checking timed systems with a large number of components. The main challenge is to obtain pertinent global timing constraints from the timings in the components alone. To this end, we make use of auxiliary clocks to automatically generate new invariants which capture the constraints induced by the synchronisations between components. The method has been implemented in the RTD-Finder tool and successfully experimented on several benchmarks

Cognitive psychopathology: The role of emotion

This paper examines the role of emotion in the understanding of psychopathology. The influential Cognitive Therapy model of Beck is briefly reviewed and a number of limitations are considered. Two particular weaknesses are highlighted in the understanding of cognitive psychopathology; namely, the importance of multi-level processing systems and the importance of emotion. The Power and Dalgleish (1997, 2008) SPAARS model is presented to show the advantages that arise from the inclusion of multilevel processes combined with a theoretical account of emotion. In order to illustrate the application of the SPAARS model to cognitive psychopathology, findings from a recent emotion profile analysis of clinical depression and anxiety are summarised. The analyses also illustrate the importance of shamerelated emotions in depression in contrast to the guiltrelated emotions that are highlighted in classification systems such as DSM-IV. ------ RESUMO ------ Neste artigo fazemos uma reflexão sobre o papel da emoção na compreensão da psicopatologia. Fazemos uma breve revisão e apontamos uma série de limitações. do influente modelo da Psicoterapia Cognitiva preconizado por Beck. Dois pontos particularmente fracos são destacados na compreensão da psicopatologia cognitiva; nomeadamente, a importância dos sistemas de processamento multi-nível e a importância das emoções. Apresentamos o modelo SPAARS de Power e Dalgleish (1997, 2008), para mostrar as vantagens que resultam da inclusão de processos de multi-nível combinados com uma teoria relacionada com as emoções. Com o objectivo de ilustrar a aplicação do modelo SPAARS à psicopatologia cognitiva. Referimos, de forma sucinta, o que foi observado numa recente analise sobre o perfil da depressão e ansiedade clínicas. Estas analises ilustram também a importância das emoções relacionadas com a vergonha na depressão, em contraste com as emoções relacionadas com a culpa que são destacadas em sistemas de classificação como o DSM-IV