52% Yes, a signiicant crisis 3% No, there is no crisis 7% Don't know 38% Yes, a slight crisis 38% Yes, a slight crisis 1,576 RESEARCHERS SURVEYED M ore than 70% of researchers have tried and failed to reproduce another scientist's experiments, and more than half have failed to reproduce their own experiments. Those are some of the telling figures that emerged from Nature's survey of 1,576 researchers who took a brief online questionnaire on reproducibility in research. The data reveal sometimes-contradictory attitudes towards reproduc-ibility. Although 52% of those surveyed agree that there is a significant 'crisis' of reproducibility, less than 31% think that failure to reproduce published results means that the result is probably wrong, and most say that they still trust the published literature. Data on how much of the scientific literature is reproducible are rare and generally bleak. The best-known analyses, from psychology 1 and cancer biology 2 , found rates of around 40% and 10%, respectively. Our survey respondents were more optimistic: 73% said that they think that at least half of the papers in their field can be trusted, with physicists and chemists generally showing the most confidence. The results capture a confusing snapshot of attitudes around these issues, says Arturo Casadevall, a microbiologist at the Johns Hopkins Bloomberg School of Public Health in Baltimore, Maryland. "At the current time there is no consensus on what reproducibility is or should be. " But just recognizing that is a step forward, he says. "The next step may be identifying what is the problem and to get a consensus. "

328The spontaneous association between numbers and space has drawn much attention since its discovery (Dehaene, Bossini, & Giraux, 1993). Well over 100 published experiments have shown that small-magnitude values are associated with the left side and larger values with the right side of space (for a recent meta-analysis, see Wood, Nuerk, Willmes, & Fischer, 2008). The association is typically found by comparing the speed of rightand left-hand responses in a parity classification task. This so-called " spatial-numerical association of response codes" (SNARC) effect has been interpreted as reflecting a "spillover" of directional reading or writing habits. 1 Readers in Western cultures progress through each line of text from left to right, and they also seem to place small numbers further on the left side of a "mental number line" than larger numbers when they enumerate objects or think about magnitudes. Supporting this explanation of the SNARC effect as a generalized habitual association, the spatial association for numbers was weaker in Iranians, who habitually read Arabic script from right to left but were only recently immersed into a left-to-right reading culture (Dehaene et al., 1993, Experiment 7). However, that study reported no data from Iranians in their native reading context, and thus no demonstration of the expected reversed association between numbers and space in right-to-left readers.A field study by Zebian (2005) tried to address this point. She reported that monoliterate Arabic readers were faster to name the side of the larger number in a pair when it was on the left side of a display than when it was on the right, suggesting a reversed association between numbers and space consistent with their right-to-left reading habits. However, the verbal naming task is not sensitive to the SNARC effect (Keus & Schwarz, 2005); this was evidenced by the absence of a normal effect in Zebian's English-speaking control group. Together, these results cast doubt on whether a reversed SNARC effect was indeed present in Zebian's (2005) study, or whether some other aspect of the task led to a spatial bias in these monoliterate Arabic readers.Ito and Hatta (2004; see also Schwarz & Keus, 2004) reported a vertical SNARC effect (small numbers associated with lower keys and larger numbers with upper keys) in Japanese readers. This association conflicts with the habitual top-to-bottom reading direction in Japanese and suggests that reading habit and SNARC effect might be independent. Recently, Hung, Hung, Tzeng, and Wu (2008) showed a horizontal mapping for Arabic number symbols, which their Chinese participants typically encountered in horizontally printed English text, and a vertical mapping for Chinese number symbols, which most often appeared in vertically printed Chinese text. Such flexibility in the same group of readers in the association of numbers with space resulting from both the number format and the associated reading context suggests that number concepts might not possess spatial associations in their own r...

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The literature on spatial associations during number processing is dominated by the SNARC (spatial-numerical association of response codes) effect. We describe spatial biases found for single digits and pairs of numbers, first in the "original" speeded parity task and then extending the scope to encompass different tasks, a range of measures, and various populations. Then we review theoretical accounts before surveying the emerging evidence for similar spatial associations during mental arithmetic. We conclude that the mental number line hypothesis and an embodied approach are useful frameworks for further studies.

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Approximate processing of numerosities is a universal and preverbal skill, while exact number processing above 4 involves the use of culturally acquired number words and symbols. The authors first review core concepts of numerical cognition, including number representation in the brain and the influential view that numbers are associated with space along a "mental number line." Then, they discuss how cultural influences, such as reading direction, finger counting, and the transparency of the number word system, can influence the representation and processing of numbers. Spatial mapping of numbers emerges as a universal cognitive strategy. The authors trace the impact of cultural factors on the development of number skills and conclude that a cross-cultural perspective can reveal important constraints on numerical cognition."The standard horizontal number line is clearly a product of culture, as it depends on culture-specific conventions of a written numeral system. But it also depends on three innate faculties: our number sense, our sense of the space around us, and the visual imagery system. The representations of our number sense are mapped onto a horizontal line (or arranged in a row) to form an integrated system of numerical representations in the imagery system; when activated, the resulting image is integrated into the representation of egocentric space. So here we have an example of a basic resource of human intelligence that is the product of an interaction between cultural and innate endowments."Numbers are ubiquitous-among other things, they specify times, locations, and wealth; in industrialized countries people process numbers to plan their day, find their way, and calculate their pay, and in more remote places people often use numerosity to keep track of livestock, children, and food. Rarely do we stop to think what an amazing achievement these numerical skills constitute. Only a few hundred years ago a large percentage of the world's population was virtually innumerate and only a minority could deal with exact numbers and perform arithmetic tasks (Ifrah, 1998). Everyday numeracy is an impressive cultural achievement that has shaped how we think about numbers and numerosities in many ways. We learn number processing, and in particular arithmetic and higher mathematical skills, through formal instruction. Differences in numerical experiences between cultures provide us with an opportunity to understand the relationship between culture, cognitive development, education, and human cognition more generally and the influence of cultural factors on the mental representation of numbers in particular. The present article describes this multifaceted relationship.

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