4,192 research outputs found
East vs. West – Developmentally Early Differences in Attention
Growing evidence indicates a suite of generalized differences in the attentional and cognitive processes of adults from Eastern and Western cultures (Nisbett, 2003). Cognition in Eastern adults is characterized as more relational and in Western adults as more object focused (Nisbett & Miyamoto, 2005). This chapter will present evidence on the early emergence of these differences in preschoolers from Japan and the U.S. and will also present initial findings on transmission of these cultural differences being very early
Probabilistic Cue Combination: Less is More
Learning about the structure of the world requires learning probabilistic relationships: rules in which cues do not predict outcomes with certainty. However, in some cases, the ability to track probabilistic relationships is a handicap, leading adults to perform non-normatively in prediction tasks. For example, in the dilution effect, predictions made from the combination of two cues of different strengths are less accurate than those made from the stronger cue alone. Here we show that dilution is an adult problem; 11-month-old infants combine strong and weak predictors normatively. These results extend and add support for the less is more hypothesis: limited cognitive resources can lead children to represent probabilistic information differently from adults, and this difference in representation can have important downstream consequences for prediction
The stellar velocity dispersion in the inner 1.3 disk scale-lengths of the irregular galaxy NGC 4449
We present measurements of the stellar velocity dispersion in the inner 1
arcmin radius (1.3 disk scale-lengths) of the irregular galaxy NGC 4449
determined from long-slit absorption-line spectra. The average observed
dispersion is 29 +/-2 km/s, the same as predicted from NGC 4449's luminosity.
No significant rotation in the stars is detected. If we assume a maximum
rotation speed of the stars from the model determined from the gas kinematics
of Hunter et al. (2002), the ratio V_max/sigma_z measured globally is 3. This
ratio is comparable to values measured in spiral galaxies, and implies that the
stellar disk in NGC 4449 is kinematically relatively cold. The intrinsic
minor-to-major axis ratio (b/a)_0 is predicted to be in the range 0.3-0.6,
similar to values derived from the distribution of observed b/a of Im galaxies.
However, V/sigma_z measured locally is 0.5-1.1, and so the circular velocity of
NGC 4449 is comparable or less than the velocity of the stars within the
central 1.3 disk scale-lengths of the galaxy.Comment: To be published in ApJ, Nov 200
Posture Affects How Robots and Infants Map Words to Objects
For infants, the first problem in learning a word is to map the word to its referent; a second problem is to remember that mapping when the word and/or referent are again encountered. Recent infant studies suggest that spatial location plays a key role in how infants solve both problems. Here we provide a new theoretical model and new empirical evidence on how the body – and its momentary posture – may be central to these processes. The present study uses a name-object mapping task in which names are either encountered in the absence of their target (experiments 1–3, 6 & 7), or when their target is present but in a location previously associated with a foil (experiments 4, 5, 8 & 9). A humanoid robot model (experiments 1–5) is used to instantiate and test the hypothesis that body-centric spatial location, and thus the bodies’ momentary posture, is used to centrally bind the multimodal features of heard names and visual objects. The robot model is shown to replicate existing infant data and then to generate novel predictions, which are tested in new infant studies (experiments 6–9). Despite spatial location being task-irrelevant in this second set of experiments, infants use body-centric spatial contingency over temporal contingency to map the name to object. Both infants and the robot remember the name-object mapping even in new spatial locations. However, the robot model shows how this memory can emerge –not from separating bodily information from the word-object mapping as proposed in previous models of the role of space in word-object mapping – but through the body’s momentary disposition in space
Inclusion of Electrochemically Active Guests by Novel Oxacalixarene Hosts
We demonstrate for the first time the utility of oxacalixarenes as hosts and investigate the forces that influence the thermodynamics of binding
Origins of Selectivity for the [2+2] Cycloaddition of α,β-unsaturated Ketones within a Porous Self-assembled Organic Framework
This article studies the origins of selectivity for the [2+2] cycloadditions of α,β-unsaturated ketones within a porous crystalline host. The host, formed by the self-assembly of a bis-urea macrocycle, contains accessible channels of ∼6 Å diameter and forms stable inclusion complexes with a variety of cyclic and acyclic α,β-unsaturated ketone derivatives. Host 1 crystals provide a robust confined reaction environment for the highly selective [2+2] cycloaddition of 3-methyl-2-cyclopentenone, 2-cyclohexenone, and 2-methyl-2-cyclopentenone, forming their respective exo head-to-tail dimers in high conversion. The products are readily extracted from the self-assembled host and the crystalline host can be efficiently recovered and reused. Molecular modeling studies indicate that the origin of the observed selectivity is due to the excellent match between the size and shape of these guests to dimensions of the host channel and to the preorganization of neighboring enones into favorable reaction geometries. Small substrates, such as acrylic acid and methylvinylketone, were bound by the host and were protected from photoreactions. Larger substrates, such as 4,4-dimethyl-2-cyclohexenone and mesityl oxide, do not undergo selective [2+2] cycloaddition reactions. In an effort to understand these differences in reactivity, we examined these host−guest complexes by thermogravimetric analysis (TGA), NMR, powder X-ray diffraction (PXRD) and molecular modeling
Manipulating the Cavity of a Porous Material Changes the Photoreactivity of Included Guests
Changing an ether to a ketone within the framework of a bis-urea macrocycle has little effect on the supramolecular assembly of this building block into porous crystals but introduces a triplet sensitizer into the framework that dramatically alters the photochemical reactions of included guests
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