Influence of the movement parameter to be controlled on manual RT asymmetries in right-handers

In this experiment we test whether the effects of manual asymmetries on movement preparation depend on the parameter (amplitude or direction) to be programmed. In two experiments, only the amplitude, or the direction, of aiming movements was constrained. Reaction and movement times were measured. Results show that RTs are always shorter for left-hand than for right-hand movements. There is an effect of target extent in the amplitude condition, but not in the direction one. RTs for ipsilateral movements are shorter than RTs for contralateral movements. These results are discussed in the light of the processes involved in setting the amplitude or direction of the movement and with regard to the competency of the two hemispheres regarding these processes.     

Naming and categorization in young children: v. manual sign training

Following pre-training with everyday objects, 8 children aged from 2 to 4 years learned to produce one manual sign (fists placed one above the other, in front of body) to one stimulus and an alternative manual sign (shoulders touched with ipsilateral hands) to the other stimulus, with each of three pairs of different arbitrary wooden shapes (Set 1). The six stimuli then were presented in category match-to-sample tests, which all subjects passed. Three of the children were next trained to produce the manual signs (denoted as fist/shoulder) for an additional six arbitrary stimuli, Set 2. All 3 children went on to pass category match-to-sample tests for Set 2, and for Set 1 and Set 2 combined. In the final experimental phase, 2 of the children were trained, for one of the six stimulus pairs, to produce the vocal tact "zag" to one stimulus and "vek" to the other. Both children showed category transfer of these vocalizations in test trials with each of the remaining five stimulus pairs, and all the stimuli combined in a 12-stimulus array. In line with Horne and Lowe's (1996) naming account, manual sign naming was found to be as effective as vocal naming in establishing arbitrary stimulus categorization, measured in terms of category sorting and transfer of function. The findings also have implications for the training of verbal repertoires in people with learning disabilities.     

Cross-cultural comparison of ADHD symptoms among Japanese and US university students

Problems related to attention, hyperactivity, and impulsiveness are known to impact social, academic, and vocational success. When the problems begin in childhood and lead to impaired functioning, the syndrome is identified as attention-deficit/hyperactivity disorder (ADHD). Symptoms of the syndrome persist into adolescence and adulthood for many individuals, but less is known about characteristics of adults compared to children, especially adults attending university. Furthermore, there is little cross-national and cross-cultural research. This study compared DSM-IV-TR ADHD symptoms of US university students (N=271) to Japanese peers (N=712). Comparison of group means on a DSM-IV-TR-based checklist indicated that Japanese students reported more problems with inattention (and overall ADHD symptoms) but not hyperactive-impulsive symptoms. Although differences were statistically significant, effect sizes were small, indicating that for practical purposes, the students reported similar levels of symptoms. Japanese students reported higher rates of meeting or exceeding symptom counts that comprise diagnostic criteria for ADHD, but differences were quite small. Using DSM-IV-TR thresholds, 5.70% of US students and 6.27% of Japanese students reported enough symptoms to meet the cut-off for inattentive, hyperactive/impulsive, or combined type during childhood. With regard to recent problems, 2.66% of US students and 4.52% of Japanese students reported enough symptoms to meet the cut-off for one of the three subtypes. Comparisons using other methods of calculating rates are also provided. This research adds to the limited knowledge of ADHD symptoms in university students across countries and it supports the view that ADHD is not merely a cultural construct. This study is among the first to identify potential attention problems in Japanese university students.     

Determining the Temporal Limits of a Visual Sample for Visual Regulation

The author examined the minimum amount of time needed for vision to increase aiming accuracy and decrease movement duration. Participants selected when they would receive a visual sample during aiming movements by pressing a switch held with the left hand. The sample was one of the following durations: 40 ms, 30 ms, 20 ms, 10 ms, or 0 ms (no vision). Decreased accuracy in the no-vision condition compared to the vision conditions was observed when the duration of the impending sample was unknown (Experiment 1). Samples 40 ms in duration were sufficient to decrease endpoint variability when the duration of the sample was known before the movement (Experiment 2). These results indicate that short visual samples can be used to decrease movement time and increase accuracy and that knowledge of the impending visual context can impact the individual's subsequent behavior.     

The Role of Oculomotor Information in the Learning of Sequential Aiming Movements

With their eyes initially on either the home, midline, or final end position, 30 participants practiced a 2-target aiming movement. After 120 acquisition trials, participants performed a retention test and were then transferred to each of the other 2 eye conditions. During acquisition, all groups improved over practice, but the home group showed the greatest improvement. The temporal improvement was most pronounced in the times spent after peak velocity. Retention and transfer tests indicated that participants performed best under eye-movement conditions that were the same as the 1 they had practiced in. There was also positive transfer of training between conditions in which the oculomotor information was similar. Thus, to optimize learning, one should practice under the same afferent and oculomotor conditions that will be required for the final performance.     

The Coding of Location

One prediction of the recent target hypothesis for movement control (MacNeilage, 1970; Russell, 1976) holds that location reproduction is not solely dependent upon stored kinesthetic information. Three experiments were performed to test this prediction by requiring the subject to reproduce the location with the limb opposite to the one used for criterion production. This switched-limb procedure was assumed to force the subject to rely upon more abstract information rather than the kinesthetic cues of the criterion movement. With movement direction invariant, switched-limb reproduction was equal to same-limb reproduction. The alteration of movement direction hampered switched-limb reproduction but same-limb reproduction was not greatly affected. These findings gave some support to the target hypothesis but suggested that the context of the movement may affect the potency of the location code. Implications of the switched-limb technique for future research were briefly discussed.     

Coupling of Eye,Finger, Elbow,and Shoulder Movements During Manual Aiming

Temporal and spatial coupling of point of gaze (PG) and movements of the finger, elbow, and shoulder during a speeded aiming task were examined. Ten participants completed 40-cm aiming movements with the right arm, in a situation that allowed free movement of the eyes, head, arm, and trunk. On the majority of trials, a large initial saccade undershot the target slightly, and 1 or more smaller corrective saccades brought the eyes to the target position. The finger, elbow, and shoulder exhibited a similar pattern of undershooting their final positions, followed by small corrective movements. Eye movements usually preceded limb movements, and the eyes always arrived at the target well in advance of the finger. There was a clear temporal coupling between primary saccade completion and peak acceleration of the finger, elbow, and shoulder. The initiation of limb-segment movement usually occurred in a proximal-to-distal pattern. Increased variability in elbow and shoulder position as the movement progressed may have served to reduce variability in finger position. The spatial-temporal coupling of PG with the 3 limb segments was optimal for the pick up of visual information about the position of the finger and the target late in the movement.     

Increasing the vocal responses of children with autism and developmental disabilities using manual sign mand training and prompt delay

The purpose of this study was to determine the effect of manual sign mand training combined with prompt delay and vocal prompting on the production of vocal responses in nonvocal children with developmental disabilities. A multiple baseline design across participants verified the effectiveness of this intervention. All participants showed increases in vocal responses following the implementation of the independent variables.     

Determinants of imitation of hand-to-body gestures in 2- and 3-year-old children

Twenty children, ten 2-year-olds and ten 3-year-olds, participated in an AB procedure. In the baseline phase, each child was trained the same four matching relations to criterion under intermittent reinforcement. During the subsequent imitation test, the experimenter modeled a total of 20 target gestures (six trials each) interspersed with intermittently reinforced baseline trials. In each session, target gestures were selected in a pre-randomized sequence from: Set 1--ear touches; Set 2--shoulder touches; Set 3--midarm touches; and Set 4--wrist touches; subjects' responses to targets were not reinforced. In each target set, half the gestures featured in nursery matching games and were termed common targets whereas the remainder, which were topographically similar but did not feature in the games, served as uncommon targets. The children produced significantly more matching responses to common target models than to uncommon ones. Common responses were also produced as mismatches to uncommon target models more often than vice versa. Response accuracy did not improve over trials, suggesting that "parity" did not serve as a conditioned reinforcer. All children showed a strong bias for "mirroring"--responding in the same hemispace as the modeler. The 2-year-olds produced more matching errors than the 3-year-olds and most children showed a bias for responding with their right hands. The strong effects of training environment (nursery matching games) are consistent with a Skinnerian account, but not a cognitive goal theory account, of imitation in young children.