Learning a keying sequence you never executed: Evidence for independent associative and motor chunk learning

A substantial amount of research has addressed how people learn and control movement sequences. Recent results suggested that practice with discrete key pressing sequences results in two types of sequence learning: associative learning and motor chunk development (Verwey & Abrahamse, 2012). In the present study, we addressed whether in keying sequences of limited length associative learning develops also when the use of the chunking mode is prevented by introducing during practice random deviants. In line with the notion of two different learning mechanisms, the present results indicate that associative sequence learning develops when motor chunks cannot be developed during practice. This confirms the notion that motor chunks do not rely on these associations. In addition, experience with a particular execution mode during the practice phase seems to benefit subsequent use of that mode with unfamiliar and random sequences. Also, participants with substantial video-gaming experience were faster in executing discrete keying sequences in the chunking mode. These last two results may point to the development of a general ability to produce movement sequences in the chunking mode

The stuff that motor chunks are made of: Spatial instead of motor representations?

In order to determine how participants represent practiced, discrete keying sequences in the discrete sequence production task, we had 24 participants practice two six-key sequences on the basis of two pre-learned six-digit numbers. These sequences were carried out by fingers of the left (L) and right (R) hand with between-hand transitions always occurring between the second and third, and the fifth and sixth responses. This yielded the so-called LLRRRL and RRLLLR sequences. Early and late in practice, the keypad used for the right hand was briefly relocated from the front of the participants to 90° at their right side. The results indicate that after 600 practice trials, executing a keying sequence relies heavily on a spatial cross-hand representation in a trunk- or head-based reference frame that after about only 15 trials is fully adjusted to the changed hand location. The hand location effect was not found with the last sequence element. This is attributed to the application of explicit knowledge. The between-hand transitions appeared to induce initial segmentation in some of the participants, but this did not consolidate into a concatenation point of successive motor chunks

Fast simulation of phase-change processes in chalcogenide alloys using a Gillespie-type cellular automata approach

Copyright © 2008 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Journal of Applied Physics 104 (2008) and may be found at http://link.aip.org/link/?JAPIAU/104/084901/1A stochastic cellular automata simulator capable of spatiotemporal modeling of the crystallization and amorphization behavior of phase-change materials during the complex annealing cycles used in optical and electrical memory applications is presented. This is based on consideration of bulk and surface energies to generate rates of growth and decay of crystallites built up from “monomers” that may themselves be quite complex molecules. The approach uses a stochastic Gillespie-type time-stepping algorithm to deal with events that may occur on a very wide range of time scales. The simulations are performed at molecular length scale and using an approximation of local free energy changes that depend only on immediate neighbors. The approach is potentially capable of spanning the length scales between ab initio atomistic modeling methods, such as density functional theory, and bulk-scale methods, such the Johnshon–Mehl–Avrami–Kolmogorov formalism. As an example the model is used to predict the crystallization behavior in the chalcogenide Ge2Sb2Te5 alloy commonly used in phase-change memory devices. The simulations include annealing cycles with nontrivial spatial and temporal variations in temperature, with good agreement to experimental incubation times at low temperatures while modeling nontrivial crystal size distributions and melting dynamics at higher temperatures

Changes in the incidental context impacts search but not loading of the motor buffer.

During a retention test, a change in the nature of the incidental contextual information present during training can have a deleterious impact on response selection by not activating particular subsets of information in memory that help direct the retrieval process. The present experiment addressed whether a change in the incidental context also impacted the completion of processes associated with loading and searching the motor buffer during motor programming. A self-select paradigm was used to describe the planning and execution of one- and four-element sequences that consisted of short and long duration key-presses. During a test phase following training, changes in the incidental contextual information impeded the search of the motor buffer. However, loading specific timing information into the motor buffer was unaffected by shifts in contexts. These data support the contention that contextual information plays a fundamental role in a broad array of movement-planning operations that involve search and retrieval type activity

Following Black Hole Scaling Relations Through Gas-Rich Mergers

We present black hole mass measurements from kinematic modeling of high-spatial resolution integral field spectroscopy of the inner regions of 9 nearby (ultra-)luminous infrared galaxies in a variety of merger stages. These observations were taken with OSIRIS and laser guide star adaptive optics on the Keck I and Keck II telescopes, and reveal gas and stellar kinematics inside the spheres of influence of these supermassive black holes. We find that this sample of black holes are overmassive ($\sim10^{7-9}$ M$_{Sun}$) compared to the expected values based on black hole scaling relations, and suggest that the major epoch of black hole growth occurs in early stages of a merger, as opposed to during a final episode of quasar-mode feedback. The black hole masses presented are the dynamical masses enclosed in $\sim$25pc, and could include gas which is gravitationally bound to the black hole but has not yet lost sufficient angular momentum to be accreted. If present, this gas could in principle eventually fuel AGN feedback or be itself blown out from the system.Comment: accepted to Ap

Displaying desire and distinction in housing

The article discusses the significance of cultural capital for the understanding of the field of housing in contemporary Britain. It explores the relationship between housing and the position of individuals in social space mapped out by means of a multiple correspondence analysis. It considers the material aspects of housing and the changing contexts that are linked to the creation and display of desire for social position and distinction expressed in talk about home decoration as personal expression and individuals' ideas of a `dream house'. It is based on an empirical investigation of taste and lifestyle using nationally representative survey data and qualitative interviews. The article shows both that personal resources and the imagination of home are linked to levels of cultural capital, and that rich methods of investigation are required to grasp the significance of these normally invisible assets to broaden the academic understanding of the field of housing in contemporary culture