How is human locomotion visually controlled? Fifty years ago, it was proposed that we steer to a goal using optic flow, the pattern of motion at the eye that specifies the direction of locomotion. However, we might also simply walk in the perceived direction of a goal. These two hypotheses normally predict the same behavior, but we tested them in an immersive virtual environment by displacing the optic flow from the direction of walking, violating the laws of optics. We found that people walked in the visual direction of a lone target, but increasingly relied on optic flow as it was added to the display. The visual control law for steering toward a goal is a linear combination of these two variables weighted by the magnitude of flow, thereby allowing humans to have robust locomotor control under varying environmental conditions.

This article introduces EsPal: a Web-accessible repository containing a comprehensive set of properties of Spanish words. EsPal is based on an extensible set of data sources, beginning with a 300 million token written database and a 460 million token subtitle database. Properties available include word frequency, orthographic structure and neighborhoods, phonological structure and neighborhoods, and subjective ratings such as imageability. Subword structure properties are also available in terms of bigrams and trigrams, biphones, and bisyllables. Lemma and part-of-speech information and their corresponding frequencies are also indexed. The website enables users either to upload a set of words to receive their properties or to receive a set of words matching constraints on the properties. The properties themselves are easily extensible and will be added over time as they become available. It is freely available from the following website: http:// www.bcbl.eu/databases/espal/. Keywords Word frequency . Subtitles . Word recognition . Corpus linguistics . PsycholinguisticsResearchers from a wide range of disciplines (e.g., neuroscience, artificial intelligence, psychology, linguistics, and education, among others) who work in the interdisciplinary area of language research (e.g., language acquisition, language processing, language learning, bilingualism, and computational linguistics) need quick and efficient access to information about specific properties of words. For example, word frequency is a dominant factor in accounting for visual word recognition speed as measured by lexical decision times (Forster & Chambers, 1973;Monsell, 1991) and eye fixation durations during reading (Rayner, 2009). Unsurprisingly, reading behavior as measured by, for example, lexical decision, naming, fixation times, and so on is affected by a wide range of other properties of words, including orthographic neighborhood

Do humans integrate experience on specific routes into metric survey knowledge of the environment, or do they depend on a simpler strategy of landmark navigation? The authors tested this question using a novel shortcut paradigm during walking in a virtual environment. The authors find that participants could not take successful shortcuts in a desert world but could do so with dispersed landmarks in a forest. On catch trials, participants were drawn toward the displaced landmarks whether the landmarks were clustered near the target location or along the shortcut route. However, when landmarks appeared unreliable, participants fell back on coarse survey knowledge. Like honeybees (F. C. Dyer, 1991), humans do not appear to derive accurate cognitive maps from path integration to guide navigation but, instead, depend on landmarks when they are available.

We examined the roles of information from optic flow and body senses (eg vestibular and proprioceptive information) for path integration, using a triangle completion task in a virtual environment. In two experiments, the contribution of optic flow was isolated by using a joystick control. Five circular arenas were used for testing: (B) both floor and wall texture; (F) floor texture only, reducing information for rotation; (W) wall texture only, reducing information for translation; (N) a no texture control condition, and (P) an array of posts. The results indicate that humans can use optic flow for path integration and are differentially influenced by rotational and translational flow. In a third experiment, participants actively walked in arenas B, F, and N, so body senses were also available. Performance shifted from a pattern of underturning to overturning and exhibited decreased variability, similar responses with and without optic flow, and no attrition. The results indicate that path integration can be performed by integrating optic flow, but when information from body senses is available it appears to dominate.

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Honeybees fly down the center of a corridor by equating the speed of optic flow in the lateral field of the two eyes. This flow-equalization strategy has been successfully implemented in mobile robots to guide behavior in cluttered environments. We investigated whether humans use a similar strategy to steer down a corridor and determined the relative contributions of equating the speed of flow (.27), the splay angles of base lines (.62), and the visual angles of texture on the left and right walls (.03) to steering behavior. A generalized equalization strategy based on the weighted linear combination of these variables closely models human behavior, providing robust visual control.

When economists ask questions about basic financial principles, most ordinary people answer incorrectly. Economic experts call this condition "financial illiteracy," which suggests that poor financial outcomes are due to a personal deficit of reading-related skills. The analogy to reading is compelling because it suggests that we can teach our way out of population-wide financial failure. In this comment, we explain why the idea of literacy appeals to policy makers in the advanced industrial nations. But we also show that the narrow skill set laid out by economists does not satisfy the politically inclusive definition of literacy that literacy studies fought for. We identify several channels through which people engage with ideas about finance and demonstrate that not all forms of literacy will lead people to the educational content prescribed by academic economists. We argue that truly financial literate people can defy the demands of financial theory and financial institutions.

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