Children's naming and word-finding difficulties: descriptions and explanations

Purpose: There are a substantial minority of children for whom lexical retrieval problems impede the normal pattern of language development and use. These problems include accurately producing the correct word even when the word?s meaning is understood; such children are often referred to as having word-finding difficulties (WFDs). This review examines the nature of naming and lexical retrieval difficulties in these and other groups of children. Method: A review of the relevant literature on lexical access difficulties in children with word finding difficulties was conducted. Studies were examined in the terms of population parameters and comparison groups included in the study. Results and Conclusions: Most discussions of the cognitive processes causing lexical retrieval difficulties have referred to semantics, phonology and processing speed. It is argued that our understanding of these topics will be further advanced by the use of appropriate methodology to test developmental models that both identify the processes in successfully performing different lexical retrieval tasks and more precisely locating the difficulties experienced by children with such tasks

The relation between naming and literacy in children with word-finding difficulties

Difficulties with picture naming tasks are associated with literacy problems. Children with dyslexia, when given naming tasks, are slower to produce words and have a higher proportion of errors (Wolf and Bowers, 1999). However, little is known about the relation between literacy and naming in other populations. This study investigates this relation in 20 children (aged 6:6 – 7:11) with word-finding difficulties (WFDs). The children in our sample performed very poorly on assessments of naming, but unlike children with dyslexia, were found to have decoding and spelling abilities within the normal range. In addition, their abilities on phonological awareness tasks were at a similar level to their decoding abilities. In contrast, performance on reading comprehension and language comprehension was significantly worse than for decoding, spelling and rhyme awareness. The implications of our findings for models concerned with understanding the relation between naming speed and literacy abilities are discussed

Acoustic echo cancellation for full-duplex voice transmission on fading channels

This paper discusses the implementation of an adaptive acoustic echo canceler for a hands-free cellular phone operating on a fading channel. The adaptive lattice structure, which is particularly known for faster convergence relative to the conventional tapped-delay-line (TDL) structure, is used in the initialization stage. After convergence, the lattice coefficients are converted into the coefficients for the TDL structure which can accommodate a larger number of taps in real-time operation due to its computational simplicity. The conversion method of the TDL coefficients from the lattice coefficients is derived and the DSP56001 assembly code for the lattice and TDL structure is included, as well as simulation results and the schematic diagram for the hardware implementation

A simple implementation of the Viterbi algorithm on the Motorola DSP56001

As systems designers design communication systems with digital rather than analog components to reduce noise and increase channel capacity, they must have the ability to perform traditional communication algorithms digitally. The use of trellis coded modulation as well as the extensive use of convolutional encoding for error detection and correction requires an efficient digital implementation of the Viterbi Algorithm for real time demodulation and decoding. Digital signal processors are now fast enough to implement Viterbi decoding in conjunction with the normal receiver/transmitter functions for lower speed channels on a single chip as well as performing fast decoding for higher speed channels, if the algorithm is implemented efficiently. The purpose of this paper is to identify a good way to implement the Viterbi Algorithm (VA) on the Motorola DSP56001, balancing performance considerations with speed and memory efficiency

"Maximizing Conservation and In-Kind Cost Share: Applying Goal Programming to Forest Protection"

This research evaluates the potential gains in benefits from using Goal Programming to preserve forestland. Two- and three-dimensional Goal Programming models are developed and applied to data from applicants to the U.S. Forest Service’s Forest Legacy Program, the largest forest protection program in the United States. Results suggest that not only do these model yield substantial increases in benefits, but by being able to account for both environmental benefits and in-kind partner cost share, Goal Programming may be flexible enough to facilitate adoption by program managers needing to account for both ecological and political factors.Goal programming, multi-objective programming, conservation optimization, forest conservation, environmental services, in-kind cost sharing, matching grants

Beyond naming patterns in children with WFDs: definitions for nouns and verbs

Children who experience difficulties in naming are described as having word finding difficulties (WFDs). In the present study 31 children with WFDs were identified through a wider survey of educational provision for those with language and communication difficulties. The children were included if they were between 6;4-7;10 years, had normal non-verbal intelligence, no major articulation difficulties and had WFDs as diagnosed by standard scores below 75 on Test of Word Finding Difficulties (TWF, German, 1989). Three control groups were identified who were matched on: chronological age (N = 31), naming age (N = 31) and level of receptive grammar (N = 31). Children?s accuracy of naming and latency to name were assessed for pictures of objects and actions. Children were asked to define the object and action terms at a later point. Children with WFDs were significantly less accurate in naming than their age matched peers but equivalent to that of the language matched peers. The group of children with WFDs were the slowest to accurately name all sets of items. All groups of children were less accurate in the provision of definitions for action terms than object terms. Overall the children with WFDs provided fewer accurate definitions than their chronological age matched peers. The nature of the children?s definitions indicated that they also differed from their language-matched peers. Particular difficulties were noted in the provision of semantic categorisation information. A range of standardised language assessments did not account for these difficulties. The findings are discussed in relation to the idea that WFDs are caused by impoverished semantic representations

Matching Grants and Charitable Giving: Why People Sometimes Provide a Helping Hand to Fund Environmental Goods

Matching grants are a prevalent mechanism for funding environmental, conservation, and natural resource projects. However, economists have largely been silent regarding the potential benefits of these mechanisms at increasing voluntary contributions. To examine the behavioral responses to different match levels, this research uses controlled laboratory experiments with generically framed instructions and introduces a general-form matching-grant mechanism, referred to as the proportional contribution mechanism (PCM). Results show that contributions are positively correlated with both the match and the induced value of the public good even when a dominant strategy is free-riding. An implication of this partial demand revelation result is that manifestations of this type of “helping hand†social preference should be counted in benefit-cost analysis.matching grants, public goods, charitable giving, voluntary contributions, experimental economics, warm glow, helping hand, Environmental Economics and Policy, Public Economics,

FOREWORD: Special Issue on Experimental Methods in Environmental, Natural Resource, and Agricultural Economics

Agricultural and Food Policy, Environmental Economics and Policy, Institutional and Behavioral Economics, Research Methods/ Statistical Methods,