Specificity of practice, visual information, and intersegmental dynamics in rapid-aiming limb movements

The authors tested the specificity of practice hypothesis on intersegmental dynamics of rapid-aiming limb movements. During acquisition, 20 participants performed an aiming task as quickly and accurately as possible either with or without vision. Following moderate (140 trials) and extensive (560 trials) practice, participants completed 20 transfer test trials in a no-vision condition. Overall, the acquisition-phase findings revealed that vision improved aiming accuracy performance but had only a slight impact on movement time and intersegmental dynamics. After 560 trials of practice, however, withdrawal of vision resulted in specificity of practice effects on intersegmental dynamics at the shoulder as well as on aiming accuracy. Taken together, those findings support and extend the specificity of practice hypothesis     

Visual Dominance in Amending the Directional Parameter of Feedforward Control

The authors examined visual dominance between trials in which the movement program was amended (i.e., off-line processing). Weighting between visual and proprioceptive feedback was examined in a trial-by-trial analysis of the directional parameter of feedforward control. Eight participants moved a cursor to a target displayed on a computer screen by manipulating a hand-held stylus on a digitizing tablet. In the first 30 trials, the cursor followed the stylus movement (practice condition). In the next 30 trials, the directional error of the stylus movement was presented in the opposite direction (reversal condition). Subjects knew the presence and the nature of the reversal. In the last 10 trials, the reversal was withdrawn (transfer condition). Directional error of feedforward control was relatively small in the practice condition, and it increased gradually in 1 of 2 directions as trials proceeded in the reversal condition. Positive aftereffect was observed in the transfer condition. A constant increment of the directional error indicated that both visual and proprioceptive feedback are registered, with higher weight on vision, and that weighting between those inputs is determined automatically or is fixed without any strategic control.     

Notice and consent: The school's responsibility to inform parents

Parental involvement in planning and placement for 20 children initially referred for special education is described in light of the PL 94-142 requirements for informed parental consent. The pattern of notification and parental involvement in the planning and placement team in four elementary schools is described, and the level of parental understanding for four components of the special education decision (eligibility, placement, program goals, and review date) is examined. Comparisons indicate that parent's versions of each decision component were clear and accurate no more than 50% of the time for any of the four components, even though parents were present at the team meeting where these decisions were rendered. The highest accuracy in parental reports was for the placement decision, while unclear or erroneous versions of decisions regarding eligibility, program goals, and review date were even more frequent. Results are interpreted in light of the amount of change demanded of local school systems to insure that parents are giving informed consent for special education planning and placement decisions.     

Ripple effect: Communication of planning team decisions to program implementers

Due process provisions are intended to insure that special education placement and programming decisions are fair. However, educators should address the issue of whether those decisions are properly implemented. This paper explores how placement decisions are communicated to the teachers and support personnel who are responsible for implementing students' special education programs. The communication network used by planning teams was characterized as informal; most information was communicated orally by many different planning team members. The results were discussed in the context of whether the messages provided to program implementers were consistent and clear.     

Exclusion constraints facilitate statistical word learning

The roles of linguistic, cognitive, and social-pragmatic processes in word learning are well established. If statistical mechanisms also contribute to word learning, they must interact with these processes; however, there exists little evidence for such mechanistic synergy. Adults use co-occurrence statistics to encode speech-object pairings with detailed sensitivity in stochastic learning environments (Vouloumanos, 2008). Here, we replicate this statistical work with nonspeech sounds and compare the results with the previous speech studies to examine whether exclusion constraints contribute equally to the statistical learning of speech-object and nonspeech-object associations. In environments in which performance could benefit from exclusion, we find a learning advantage for speech over nonspeech, revealing an interaction between statistical and exclusion processes in associative word learning.