171,359 research outputs found
Chronology of the site of Grotte du Renne, Arcy-sur-Cure, France: implications for Neanderthal symbolic behaviour
No full textHigham et al (2010) published a large series of new dates from the key French Palaeolithic site of the Grotte duRenne at Arcy-sur-Cure. The site is important because it is one of only two sites in Europe in which Châtelperronianlithic remains co-occur with Neanderthal human remains. A large series of dates from the Mousterian, Châtelperronian, Aurignacian and Gravettian levels of the site was obtained. The 14C results showed great variability, which Higham et al (2010) interpreted as most likely to be due to mixing of archaeological material in the site. In contrast, Caron et al (2011) suggested that the site stratigraphy is well preserved and that the problem with the variability in the radiocarbon ages was due to unremoved contamination in the dated bone. In this paper we address their critique of the original Higham et al (2010) pape
Trace-strength and source-monitoring accounts of accuracy and metacognitive resolution in the misinformation paradigm
No full textTwo experiments are reported that investigate the impact of misinformation on memory accuracy and metacognitive resolution. In Experiment 1, participants viewed a series of photographs depicting a crime scene, were exposed to misinformation that contradicted details in the slides, and later took a recognition memory test. For each answer, participants were required to indicate whether they were willing to testify (report) their answer to the Court and to rate confidence. Misinformation impaired memory accuracy but it had no effect on resolution, regardless of whether resolution was indexed with confidence-rating measures (gamma correlation and mean confidence) or a report-option measure (type-2 discrimination: d’). In Experiment 2, a similar accuracy-confidence dissociation was found, and the misinformation effect occurred mostly with fine-grained responses, suggesting that responding was based on recollected details. We argue that the results support source-monitoring accounts of accuracy and resolution rather than accounts based on trace strength
Global subjective memorability and the strength-based mirror effect
No full textBetween-list manipulations of memory strength through repetition commonly generate a mirror effect, with more hits, and fewer false alarms for strengthened items. However, this pattern is rarely seen with within-list manipulations of strength. Three experiments investigated the conditions under which a within-list mirror effect of strength (items presented once or thrice) is observed. In Experiments 1 and 2, we indirectly manipulated the overall subjective memorability of the studied lists by varying the proportion of non-words. A within-list mirror effect was observed only in Experiment 2, where a higher proportion of non-words was presented in the study list. In Experiment 3, the presentation duration for each item (0.5 s versus 3 s) was manipulated between groups with the purpose of affecting subjective memorability: A within-list mirror effect was observed only for the short-presentation durations. Thus, across three experiments, we found the within-list mirror effect only under conditions of poor overall subjective memorability. We propose that when the overall subjective memorability is low, people switch their response strategy on an item-by-item basis, and that this generates the observed mirror effect. <br/
Implicit learning of conjunctive rule sets: An alternative to artificial grammars
No full textA single experiment is reported that investigated implicit learning using a conjunctive rule set applied to natural words. Participants memorized a training list consisting of words that were either rare-concrete and common-abstract or common-concrete and rare-abstract. At test, they were told of the rule set, but not told what it was. Instead, they were shown all four word types and asked to classify words as rule-consistent words or not. Participants classified the items above chance, but were unable to verbalize the rules, even when shown a list that included the categories that made up the conjunctive rule and asked to select them. Most participants identified familiarity as the reason for classifying the items as they did. An analysis of the materials demonstrated that conscious micro rules (i.e., chunk knowledge) could not have driven performance. We propose that such materials offer an alternative to artificial grammar for studies of implicit learning
Not all errors are created equal: metacognition and changing answers on multiple-choice tests
No full textTwo experiments investigated the role of metacognition in changing answers to multiple-choice, general-knowledge questions. Both experiments revealed qualitatively different errors produced by speeded responding versus confusability amongst the alternatives; revision completely corrected the former, but had no effect on the latter. Experiment 2 also demonstrated that a pretest, designed to make participants' actual experience with answer changing either positive or negative, affected the tendency to correct errors. However, this effect was not apparent in the proportion of correct responses; it was only discovered when the metacognitive component to answer changing was isolated with a Type 2 signal-detection measure of discrimination. Overall, the results suggest that future research on answer changing should more closely consider the metacognitive factors underlying answer changing, using Type 2 signal-detection theory to isolate these aspects of performance
Analysis of the singular value decomposition as a tool for processing microarray expression data
No full textWe give two informative derivations of a spectral algorithm for clustering and partitioning a bi-partite graph. In the first case we begin with a discrete optimization problem that relaxes into a tractable continuous analogue. In the second case we use the power method to derive an iterative interpretation of the algorithm. Both versions reveal a natural approach for re-scaling the edge weights and help to explain the performance of the algorithm in the presence of outliers. Our motivation for this work is in the analysis of microarray data from bioinformatics, and we give some numerical results for a publicly available acute leukemia data set
Computing mean first exit times for stochastic processes using multi-level Monte Carlo
No full textThe multi-level approach developed by Giles (2008) can be used to estimate mean first exit times for stochastic differential equations, which are of interest in finance, physics and chemical kinetics. Multi-level improves the computational expense of standard Monte Carlo in this setting by an order of magnitude. More precisely, for a target accuracy of TOL, so that the root mean square error of the estimator is O(TOL), the O(TOL-4) cost of standard Monte Carlo can be reduced to O(TOL-3|log(TOL)|1/2) with a multi-level scheme. This result was established in Higham, Mao, Roj, Song, and Yin (2013), and illustrated on some scalar examples. Here, we briefly overview the algorithm and present some new computational results in higher dimensions
Early agriculture at the crossroads of China and Southeast Asia: Archaeobotanical evidence and radiocarbon dates from Baiyangcun, Yunnan
No full textWe report archaeobotanical results from systematic flotation at what is presently the earliest Neolithic site with hard evidence for crop cultivation in the Southwestern Chinese province of Yunnan, at the site of Baiyangcun. Direct AMS dates on rice and millet seeds, included together in a Bayesian model, suggests that sedentary agricultural occupation began ca. 2650 BCE, with cultivation of already domesticated rice (Oryza sativa), broomcorn millet (Panicum miliaceum), and foxtail millet (Setaria italica). Soybean (Glycine cf. max) was also present and presumably cultivated, although it still resembles its wild progenitor in terms of seed size. Additional possible cultivars include melon (Cucumis melo) and an unknown Vigna pulse, while wild gathered resources include fruits and nuts, including hawthorn (Crateagus) and aquatic foxnut (Euryale ferox). Weed flora suggests at least some rice was cultivated in wet (flooded or irrigated fields), while dryland weeds may derive from millet fields. This subsistence system persisted throughout the site's occupation, up to ca. 2050 BCE. These data provide secure evidence for the spread of Chinese Neolithic crops to Yunnan, and provide new evidence for reconstructing possible sources of cereal agriculture in mainland Southeast Asia
- …
