Collaboration and Memory: Effects of Dyadic Retrieval on Different Memory Tasks

Collaborative retrieval was investigated in two experiments. The experiments were explicitly designed to investigate how different types of memory tasks were affected by two individuals working together compared to individuals working on their own. A nominal group score was treated as the predicted potential a dyad could attain. In Experiment 1, semantic and episodic retrieval were employed. The episodic task was to encode and retrieve a story and the semantic task was to answer, without any encoding, 20 questions from the same history domain as the episodic task. In Experiment 2, explicit recognition and implicit retrieval of dot patterns were employed. The explicit recognition task was forced-choice, and in the implicit task, subjects were instructed to complete a pattern they saw from an incomplete pattern. The results suggest that: (1) dyads suffer from collaboration relative to the predicted potential, (2) the reduction of productivity for dyads was limited to explicit and episodic memory tasks, and (3) friends as opposed to non-friends reduced the negative effect of collaboration. The results replicate and extend the results from a previous study.     

Against global method safety

The global method safety account of knowledge states that an agent’s true belief that p is safe and qualifies as knowledge if and only if it is formed by method M, such that her beliefs in p and her beliefs in relevantly similar propositions formed by M in all nearby worlds are true. This paper argues that global method safety is too restrictive. First, the agent may not know relevantly similar propositions via M because the belief that p is the only possible outcome of M. Second, there are cases where there is a fine-grained belief that is unsafe and a relevantly similar coarse-grained belief (with looser truth conditions) that is safe and where both beliefs are based on the same method M. Third, the reliability of conditional reasoning, a basic belief-forming method, seems to be sensitive to fine-grained contents, as suggested by the wide variation in success rates for thematic versions of the Wason selection task.

     

Can a Robot Be a Good Colleague?

Science and Engineering Ethics - This paper discusses the robotization of the workplace, and particularly the question of whether robots can be good colleagues. This might appear to be a strange...     

Coherentist Contraction

A model of coherentist belief contraction is constructed. The outcome of belief contraction is required to be one of the coherent subsets of the original belief set, and a set of plausible properties is proposed for this set of coherent subsets. The contraction operators obtained in this way are shown to coincide with well-known belief base operations. This connection between coherentist and foundationalist approaches to belief change has important implications for the philosophical interpretation of models of belief change.     

Generalizability of carry-over effects in the emotional Stroop task

The emotional Stroop task has been the most widely used task to examine attentional bias to emotionally salient stimuli. In one format of this task, words are presented to participants in a mixed randomized or quasi-randomized sequence. Using a mixed smoking Stroop task, we have previously demonstrated that smokers are slower to respond to words which follow smoking-related words than words which follow neutral words. Here we show that this carry-over effect is present in heroin addicts-but not control subjects-in a heroin Stroop task, and in normal subjects in a stress Stroop task. Thus, the effect generalizes to other populations. In addition, an examination of the studies that have collected data from both mixed and blocked formats provides converging evidence for the presence of carry-over effects. We discuss the implications of the carry-over effect for research using the emotional Stroop task.     

Inferring the structure of latent class

Present optimization techniques in latent class analysis apply the expectation maximization algorithm or the Newton-Raphson algorithm for optimizing the parameter values of a prespecified model. These techniques can be used to find maximum likelihood estimates of the parameters, given the specified structure of the model, which is defined by the number of classes and, possibly, fixation and equality constraints. The model structure is usually chosen on theoretical grounds. A large variety of structurally different latent class models can be compared using goodness-of-fit indices of the chi-square family, Akaike’s information criterion, the Bayesian information criterion, and various other statistics. However, finding the optimal structure for a given goodness-of-fit index often requires a lengthy search in which all kinds of model structures are tested. Moreover, solutions may depend on the choice of initial values for the parameters. This article presents a new method by which one can simultaneously infer the model structure from the data and optimize the parameter values. The method consists of a genetic algorithm in which any goodness-of-fit index can be used as a fitness criterion. In a number of test cases in which data sets from the literature were used, it is shown that this method provides models that fit equally well as or better than the models suggested in the original articles.     

Welfare,Justice, and Pareto Efficiency

In economic analysis, it is usually assumed that each individuals well-being (mental welfare) depends on her or his own resources (material welfare). A typology is provided of the ways in which one persons well-being may depend on the material resources of other persons. When such dependencies are taken into account, standard Paretian analysis of welfare needs to be modified. Pareto efficiency on the level of material resources need not coincide with Pareto efficiency on the level of well-being. A change in economic conditions that is Pareto efficient in the standard sense, i.e., with respect to material resources, may nevertheless sacrifice one persons well-being to that of another. It is shown that under plausible assumptions, Pareto efficiency on the level of well-being may require the reduction of inequality on the level of material resources.     

Preservation of autobiographical memory in a case of pure progressive amnesia

G.D., a 79 year-old female, presents with a severe and slowly progressive amnesia although she remains entirely independent in daily life and is perfectly well spatially oriented. Her amnesia is relatively isolated and her deficit does not embrace other cognitive domains. G.D. underwent extensive neuropsychological evaluation including language, executive functions, perceptual, and memory tests. Based on clinical observation, the purpose of this study was to determine whether there was a dissociation between her autobiographical and semantic memory. Results point out a severely degraded semantic knowledge of famous public events and persons while autobiographical memory of personally experienced and relevant information remains intact. Results from this study and from previous studies seem to suggest that relative sparing of hippocampal structures may be related to the preservation of autobiographical memory.