1,720,996 research outputs found

    Inductive reasoning and implicit memory: evidence from intact ands impaired memory system.

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    In this study, we modified a classic problem solving task, number series completion, in order to explore the contribution of implicit memory to inductive reasoning. Participants were required to complete number series sharing the same underlying algorithm (e.g., +2), differing in both constituent elements (e.g., 2468 versus 57911) and correct answers (e.g., 10 versus 13). In Experiment 1, reliable priming effects emerged, whether primes and targets were separated by four or ten fillers. Experiment 2 provided direct evidence that the observed facilitation arises at central stages of problem solving, namely the identification of the algorithm and its subsequent extrapolation. The observation of analogous priming effects in a severely amnesic patient strongly supports the hypothesis that the facilitation in number series completion was largely determined by implicit memory processes. These findings demonstrate that the influence of implicit processes extends to higher level cognitive domain such as induction reasoning

    Alzheimer's disease and mild cognitive impairment: Effects of shifting and interference in simple arithmetic.

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    The present study investigated arithmetic processing in patients with mild dementia of Alzheimer's type (DAT) and patients with mild cognitive impairment (MCI) without dementia. Arithmetic processing (e.g., 2+3=?, 3 x 4=?) was evaluated in (1) 'blocked' condition (without extra load on attentional and executive functions), in (2) 'mixed' condition (shifting between different operations was required), and in (3) 'Stroop-like' condition (executive control and inhibition of automatic retrieval processes were needed). Both DAT and MCI patients showed intact arithmetic knowledge retrieval from long-term memory in the blocked condition. However, DAT patients were compromised whenever load was put on executive functions, whereas MCI patients succeeded to shift between operations (mixed condition) but had difficulties to inhibit overlearned associations (Stroop-like condition). In line with previous studies, these findings point to the contribution of attentional and executive functions in arithmetic. The present investigation is also of clinical relevance: it suggests that it may be important to assess arithmetic processing not only in blocked presentation but also in mixed presentation. The mixed condition has a high ecological value because it mimics daily-life arithmetic activities (e.g., checking the grocery bill). As indicated by the present results, DAT and MCI patients who are in the normal range at routine neuropsychological (blocked) arithmetic assessments may experience difficulties by extra requirement of non-numerical resources. That means, they possibly process arithmetic not efficiently in daily-life situations

    Cognitive training improves ratio processing and decision making in patients with mild cognitive impairment

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    Background: Patients with mild cognitive impairment (MCI) show lower decision making and ratio processing abilities as compared to healthy peers. Objective: To evaluate whether cognitive training on number processing and/or executive functions improves performance on ratio processing and decision making under risk. Methods: In a controlled cross-over study, patients with MCI (n = 23; mean MMSE 26.48, SD 2.43) underwent a week of numerical training followed by a week of executive-functions training (subgroup A), or vice versa (subgroup B). Before training (T1), patients performed experimental tasks of decision making (Game of Dice Task, GDT; Probability-Associated Gambling task, PAG-60 task) and of ratio processing as well as a neuropsychological background assessment. Experimental tasks were also administered after the first (T2) and the second (T3) training week. Results: The numerical training and the training of executive functions had a differential effect on experimental tasks of ratio processing. Only the numerical training proved to be effective. The effects of the two training types on decision making under risk were less clear-cut. While no changes over time were observed in the GDT, performance on the PAG-60 task improved in both training subgroups. These improvements were apparent in one subgroup after a period of executive-functions training, in the other subgroup after both training weeks. That means, improvements are not attributable to one specific training type. Conclusion: Patients with MCI can profit from a cognitive training on number processing and executive functions. Improvements are reflected in higher ratio processing abilities and more advantageous decisions after training. These results are consistent with assumptions of current cognitive models

    Going Beyond Counting First Authors in Author Co-citation Analysis

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    The present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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