Additivity in prism adaptation as manifested in intermanual and interocular transfer

Level of adaptation was assessed in both exposed and unexposed eye and/or hand for visual shift (VS), proprioceptive shift (PS), and the eye-hand coordination, negative after effect (NA) measure of both visual and proprioceptive change, following 15-min and 20-diopter base-right displacement viewing of the active hand, under conditions of unconstrained head movement and terminal exposure feedback. Transfer was complete for the VS test, and significant, but incomplete for the PS and NA tests. For both exposed and unexposed eye/hand situations, level of adaptation was greater for the NA than for the PS test, which in turn showed greater adaptation than the VS test. Additivity was virtually perfect for the unexposed eye/hand (VS+PS = NA), but underadditivity appeared for the exposed eye/hand (VS+PS < NA). This underadditivity was approximately equal in magnitude to the amount that transfer on the NA test was less than on the PS test, suggesting that underadditivity was due to a nontransferable, assimilated corrective response in the NA test with the exposed eye/hand. Possible explanations for intermanual transfer are discussed.     

Adaptive coordination and alignment of eye and hand

Under spatial misalignment of eye and hand induced by laterally displacing prisms (11.4 degrees in the rightward direction), subjects pointed 60 times (once every 3 s) at a visually implicit target (straight ahead of nose, Experiment 1) or a visually explicit target (an objectively straight-ahead target, Experiment 2). For different groups in each experiment, the hand became visible early in the sagittal pointing movement (early visual feedback). Adaptation to the optical misalignment during exposure (direct effects) was rapid, especially with early feedback; complete compensation for the misalignment was achieved within about 30 trials, and overcompensation occurred in later trials, especially with an explicit target. In contrast, adaptation measured with the misalignment removed and without visual feedback after blocks of 10 pointing trials (aftereffects) was slow to develop, especially with delayed feedback and an implicit target; at most, about 40% compensation for the misalignment occurred after 60 trials. This difference between direct effects and aftereffects is discussed in terms of separable adaptive mechanisms that are activated by different error signals. Adaptive coordination is activated by error feedback and involves centrally located, strategically flexible, short-latency processes to correct for sudden changes in operational precision that normally occur with short-term changes in coordination tasks. Adaptive alignment is activated automatically by spatial discordance between misaligned systems and involves distributed, long-latency processes to correct for slowly developing shifts in alignment among perceptual-motor components that normally occur with long-term drift. The sudden onset of misalignment in experimental situations activates both mechanisms in a complex and not always cooperative manner, which may produce overcompensatory behavior during exposure (i.e., direct effects) and which may limit long-term alignment (i.e., aftereffects).     

Predictors of Placement Outcomes in Treatment Foster Care: Implications for Foster Parent Selection and Service Delivery

Treatment foster care (TFC) is a normalizing environment in which to treat those children whose particular needs are not addressed in traditional foster care and for whom an institutional setting is a restrictive and unnecessary alternative. However, when the foster care placements of these emotionally and behaviorally disturbed children fail, as they often do, the children are shifted from one home to another without the opportunity to experience permanence or emotional attachment, resulting in poor adjustment to foster care. Placement stability, which depends in part upon effective matching of foster children with potential foster families, is critical for achieving positive outcomes in TFC. Yet, there is a dearth of information to guide placement agencies in making decisions about matching foster children with families. Moreover, once a successful match has been made, it is equally vital that service delivery be of high quality so that permanence is maintained. We review research on the predictors of positive outcomes in foster care, focusing on studies involving emotionally or behaviorally disturbed children, and provide recommendations for selecting foster parents and for ensuring high quality foster care services and placement stability.     

Demographic variables, smoking variables, and outcome across five studies.

OBJECTIVE: Intervention effectiveness can potentially be affected by membership in different demographic subgroups (race, ethnicity, gender, age, and education level) or smoking behavior variables (time to first cigarette, longest previous quit attempt, number of attempts in the past year, number of cigarettes, and stage of change). Previous research on these 2 sets of variables has produced mixed results. DESIGN: This secondary data analysis combined data from 5 effectiveness trials (a random-digit-dial sample [N=1,358], members of an HMO [N=207], parents of students recruited for a school-based study [N=347], patients from an insurance provider list [N=535], and employees [N=175]) in which smokers were all proactively recruited from a defined population and all received the same expert system intervention. The intervention produced a consistent 22% to 26% point prevalence cessation rate across the 5 studies. MAIN OUTCOME MEASURES: The main outcome measures were 24-hr point prevalence, 7-day point prevalence, 30-day prolonged abstinence, and 6-month prolonged abstinence. RESULTS: There were no significant differences in outcome across gender, race, and ethnicity subgroups. There were significant differences and small effect sizes for age and education subgroups. There were significant differences and large effect sizes for all 5 smoking behavior variables. DISCUSSION: Demographic variables are static variables, whereas the smoking variables are more dynamic, that is, open to change. Given the dynamic nature of the smoking variables and the large effect sizes, interventions tailored on the smoking variables should be more successful.     

Cluster subtypes within the precontemplation stage of change for sun protection behavior

The aim of this study is to identify replicable cluster subtypes within the precontemplation stage of change for sun protection. Secondary data analysis of baseline data from a sample of participants in a home-based expert system intervention was performed. Three random samples were selected from participants in the precontemplation stage (N = 570). Cluster analyses were performed using the scales of pros, cons, and self-efficacy. Interpretability of pattern, pseudo F-test, and dendograms were used to determine the number of clusters. A four-cluster solution replicated across subsamples. Significant differences between clusters on the nine processes of change and on behavioral measures were found. Cluster solutions were robust, interpretable and with good initial external validity. They replicated patterns found for other behaviors, demonstrating long-term predictability and providing basis for tailored interventions.     

The Effects of Time and Distance on Accuracy of Target-Directed Locomotion

Dual adaptation to different amounts or directions of prismatic displacement, or both, can be acquired and maintained with little mutual interference. Associative recalibration of the regional task- or workspace, contingent on differentiation of distinguishing sensory information, can explain such adaptation. In contrast, nonassociative realignment restores dimensional mapping among spatial representations. Methods for measuring the separate contributions of those 2 kinds of prism adaptation are identified in the present article. On the basis of a critique of dual-adaptation studies, the authors suggest that recalibration can explain the data but that the method used in those experiments confounded realignment and might have obscured the effectiveness of dual-calibration training.     

Intermanual transfer of prism adaptation

The authors measured intermanual transfer in participants (N = 48) whose exposed or unexposed right or left hand was tested 1st after participants experienced prismatic displacement. Test order did not affect either participants' performance during prismatic exposure or the usual aftereffects, but transfer occurred only when the authors tested the exposed right hand 1st. Transfer did not occur, and proprioceptive shift for the exposed left limb decreased when the authors tested the unexposed right limb 1st. The present results suggest that transfer occurs during testing for aftereffects of prism exposure, but not during prism exposure itself, as researchers have previously assumed. Results are consistent with those of previous research that has shown that limb control is lateralized in opposite hemispheres and that the left hemisphere contains a spatial map only for the right limb.