Different Strategies for Using Motion-in-Depth Information in Catching.

Previous studies on ball catching have had the limitation that the catcher was restricted to lateral hand movements. The authors investigated catching behavior in the more natural situation in which hand movements were unconstrained. Movements of the hand were tracked as participants tried to "catch" an approaching ball simulated with changing size and/or changing disparity. Participants used 1 of 2 distinct interception strategies: (a) a "cutting-off" strategy where time to passage (TTP) information was used to guide movements of the hand in depth such that the ball was caught farther in front of the face when the ball was approaching more slowly and (b) a "waiting" strategy where the hand was moved along a frontoparallel plane that was constant across ball trajectories and speeds. Cue dissociation and selective adaptation manipulations demonstrated that the catcher's estimates of TTP and crossing distance were based on a combination of binocular and monocular information. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Catching balls: How to get the hand to the right place at the right time.

Information specifying the future passing distance of an approaching object is available (in units of object size) in the ratio of optical displacement velocity and optical expansion velocity. Despite empirical support for the assumption that object size can serve as a metric in the perception of passing distance, the present series of experiments reveals that in catching a ball Ss do not rely on such "point-predictive" information. The angle at which real and simulated balls approached an S systematically affected verbal and manual estimates of future passing distance, as well as the kinematic characteristics of catching movements. To catch a ball, the S uses momentary action-related information instead of spatiotemporal estimates. The hand velocity is geared to information specifying the currently required velocity. This secures ending up at the right place in the right time, regardless of where this may be. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Optical Trajectories and the Informational Basis of Fly Ball Catching.

D. M. Shaffer and M. K. McBeath (see record 2002-02027-006) plotted the optical trajectories of uncatchable fly balls and concluded that linear optical trajectory is the informational basis of the actions taken to catch these balls. P. McLeod, N. Reed, and Z. Dienes (see record 2002-11140-016) replotted these trajectories in terms of changes in the tangent of optical angle over time and concluded that optical acceleration is the informational basis of fielder actions. Neither of these conclusions is warranted, however, because the optical trajectories of even uncatchable balls confound the information that is the basis of fielder action with the effects of those same actions on these trajectories. To determine the informational basis of fielder action, it is necessary to do the control-theory-based Test for the Controlled Variable, in which the informational basis of catching is found by looking for features of optical trajectories that are protected from experimentally or naturally applied disturbances. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Lateral interception I: Operative optical variables, attunement, and calibration.

J. J. Gibson (1966, 1979) suggested that improvement in perception and action can be attributed in part to changes in which variable is attended to. Such reattunement has been demonstrated with observers making judgments in response to simulations. The present study sought attunement changes in the perception of real events and in visually guided action. In 3 experiments, adults judged the passing distance of or attempted to catch balls. Discrete measures and the predictions of a modified required velocity model (e.g., R. J. Bootsma, V. Fayt, F. T. J. M. Zaal, & M. Laurent, 1997) were used to reveal which variables were exploited. Participants differed from each other and, to some extent, changed in the optical variables used, in catching as well as judging. Nevertheless, the changes were much smaller than in previous simulation-judgment studies; calibration was also found to underlie the improvements in performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Gender differences in the development and adult outcome of co-occurring depression and delinquency in adolescence.

Using a dual trajectory modeling approach, we examined co-occurring trajectories of depression and delinquency from age 11 to age 18 and their relation to adult outcome six years later in a community sample of 1423 (674 boys) adolescents. We also examined the effects of childhood externalizing, internalizing, and social problems on trajectory membership for depression and delinquency. The results showed that although more girls than boys were likely to follow high-level, co-occurring trajectories on depression and delinquency, the adult outcome of adolescents following high-level trajectories on both domains was poorer for boys than for girls. However, the combination of decreasing depression symptoms and increasing delinquency symptoms across adolescence was related with poorer adult outcomes for girls compared to boys. Finally, whereas boys' high-level co-occurring trajectory of depression and delinquency was predicted by childhood aggression, girls' equivalent trajectory was predicted by childhood depression and delinquency. The findings support the “gender paradox” effect (Loeber & Keenan, 1994) stating that in disorders with an unequal gender ratio, members of the gender with the lower prevalence rate tend to be more seriously affected in terms of comorbidity and poor outcome. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Curved saccade trajectories reveal conflicting predictions in associative learning.

We report how the trajectories of saccadic eye movements are affected by memory interference acquired during associative learning. Human participants learned to perform saccadic choice responses based on the presentation of arbitrary central cues A, B, AC, BC, AX, BY, X, and Y that were trained to predict the appearance of a peripheral target stimulus at 1 of 3 possible locations, right (R), mid (M), or left (L), in the upper hemifield. We analyzed as measures of associative learning the frequency, latency, and curvature of saccades elicited by the cues and directed at the trained locations in anticipation of the targets. Participants were trained on two concurrent discrimination problems A+R, AC+R, AX+M, X+M and B+L, BC+L, BY+M, Y+M. From a connectionist perspective, cues were predicted to acquire associative links connecting the cues to the trained outcomes in memory. Model simulations based on the learning rule of the Rescorla and Wagner (1972) model revealed that for some cues, the prediction of the correct target location was challenged by the interfering prediction of an incorrect location. We observed that saccades directed at the correct location in anticipation of the target curved away from the location that was predicted by the interfering association. Furthermore, changes in curvature during training corresponded to predicted changes in associative memory. We propose that this curvature was caused by the inhibition of the incorrect prediction, as previously has been suggested with the concept of distractor inhibition (Sheliga, Riggio, & Rizzolatti, 1994; Tipper, Howard, & Houghton, 2000). The paradigm provides a new method to examine memory interference during associative learning. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Signal-dependent noise determines motor planning

When we make saccadic eye movements or goal-directed arm movements, there is an infinite number of possible trajectories that the eye or arm could take to reach the target. However, humans show highly stereotyped trajectories in which velocity profiles of both the eye and hand are smooth and symmetric for brief movements. Here we present a unifying theory of eye and arm movements based on the single physiological assumption that the neural control signals are corrupted by noise whose variance increases with the size of the control signal. We propose that in the presence of such signal-dependent noise, the shape of a trajectory is selected to minimize the variance of the final eye or arm position. This minimum-variance theory accurately predicts the trajectories of both saccades and arm movements and the speed-accuracy trade-off described by Fitt's law. These profiles are robust to changes in the dynamics of the eye or arm, as found empirically. Moreover, the relation between path curvature and hand velocity during drawing movements reproduces the empirical 'two-thirds power law. This theory provides a simple and powerful unifying perspective for both eye and arm movement control.     

A test of models of personality disorder configuration.

In this study, the authors examined the degrees to which various models of personality disorder (PD) configuration are consistent with the primary data sets from clinical and community samples reported in the recent literature. Factor analyses were conducted on PD intercorrelation matrices, and the loading matrices were rotated to maximum possible fit with target matrices representing the PD configuration models. There was little support for the interpersonal circle or other circular orderings of PDs, or for T. Millon's (1990, 1996) biosocial learning theory. There was moderate support for the Diagnostic and Statistical Manual of Mental Disorders (4th ed., DSM-IV; American Psychiatric Association, 1994) dimensions, for C. R. Cloninger's (1987) tridimensional theory, and for S. Torgersen and R. Alnaes's (1989) decision tree. There was consistent, stronger support for the 5-factor model (T. A. Widiger, T. J. Trull, J. F. Clarkin, C. Sanderson, & P. T. Costa, 1994) and for an empirically derived 7-factor model by C. R. Cloninger and D. M. Svrakic (1994). However, a focus on just 4 factors seems preferable and sufficient. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Trajectory formation based on physiological characteristics of skeletal muscles

Human arm trajectories in natural unrestricted reaching movements were studied. They have particular properties such that a hand path is a rather simple straight or curved line, and a tangential velocity profile of hand is bell-shaped. Also these properties are invariant, independent of movement duration and hand-held load. In this study, trajectory formation is investigated on the basis of physiological characteristics of skeletal muscles, and a criterion prescribed by a derivative of isometric muscle torque is proposed. Subsequently, optimal trajectories are formulated under various conditions of movement to account for a planning strategy of human arm trajectories. In addition to such a theoretical approach, human arm trajectories are experimentally observed by a measuring system which provides a visual sensor and a target tracking device, enabling totally unrestricted movements. Then, optimal trajectories are quantitatively evaluated in comparison with experimental data in which essential properties of human arm trajectories are demonstrated. These results support the idea that human arm trajectories are planned in order to minimize the proposed criterion which is determined from physiological aspects. Finally, the physiological advantages of human arm trajectories are discussed with regard to the analysis of observed and optimal trajectories.     

Mandibular implant-retained overdenture: finite element analysis of two anchorage systems

Human arm movements towards visual targets are remarkably reproducible in several tasks and conditions. Various authors have reported that trajectories of unconstrained point-to-point movements are slightly curved, smooth and have bell-shaped velocity profiles. The hand paths of such movements show small - but significant - curvatures throughout the workspace. The cause of these curvatures is still obscure. Traditionally this curvature is explained as the result of an optimisation process or is ascribed to mechanical or dynamic properties of the effector system. Recently, however, it has been suggested that these curvatures are due at least partly, to the visual misperception of straight lines. To evaluate the latter hypothesis, we compared unconstrained, self-paced point-to-point movements that subjects made with their right and left hand. We assume that the visual misperception may depend on the position in the workspace, subject, etc. but not on the hand used to make the movement. Therefore we argue that if curvature is caused by a visual misperception of straight lines, curvatures should be the same for movements made with the left and right hand. Our experiments cast strong doubt on the hypothesis that curvatures are the result of a visual distortion, because curvatures of the left hand trajectories, mirrored in the mid-sagittal plane, are found to be accurately described by trajectories of the right hand. Estimates of the effect of visual distortion on movement curvature show that, if present, this effect is very small compared with other sources that contribute to movement curvature. We found that curvatures depend strongly on the subject and on the direction and distance of the movement. Curvatures do not seem to be caused purely by the dynamic properties of the arm, since curvatures do not change significantly with increasing movement velocity. Therefore, we conclude that curvatures reflect an inherent property of the control of multi-joint arm movements.     

Perceiving and tracking kinesthetic stimuli: Further evidence of motor–perceptual interactions.

Two experiments pursued previous studies (P. Viviani & P. Mounoud, 1990; P. Viviani & N. Stucchi, 1989) on motor–perceptual interactions. The right arm of blindfolded participants was moved passively along elliptic trajectories. Kinematics was either coherent or at variance with the relation (two-thirds power law) observed in active movements. In Experiment 1 participants compared the horizontal and vertical extent of the ellipses. Kinematics affected aspect ratio discrimination: The direction along which the movement decelerated was subjectively stretched. In Experiment 2 participants used the left arm to reproduce in real time the movement of the right arm. The trajectories of the left arm presented a stretch similar to the perceptual illusion demonstrated in Experiment 1. Between-arm asynchrony suggests that the motor control system cannot use kinesthetic information that is at variance with the flow of reafferences normally associated with voluntary movements. It is argued that these interactions occur at the level of a central amodal representation of the stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Minimum-jerk, two-thirds power law, and isochrony: converging approaches to movement planning.

Two approaches to the study of movement planning were contrasted. Data on the drawing of complex two-dimensional trajectories were used to test whether the covariations of the kinematic and geometrical parameters of the movement formalized by the two-thirds power law and by the isochrony principle (P. Viviani & R. Schneider, 1991) can be derived from the minimum-jerk model hypothesis (T. Flash & N. Hogan, 1985). The convergence of the 2 approaches was satisfactory insofar as the relation between tangential velocity and curvature is concerned (two-thirds power law). Global isochrony could not be deduced from the optimal control hypothesis. Scaling of velocity within movement subunits can instead be derived from the minimum jerk hypothesis. The implications vis-à-vis the issue of movement planning are discussed with an emphasis on the representation used by the motor control system for coding the intended trajectories. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The spatiotemporal structure of control variables during catching

The discrepancy between traditional (force scaling models) and the more recently conceived dynamic explanations of load compensation (lambda model) was the departure point for the present study. By using the complex "open" motor skill of catching a ball--rather than the traditional "closed" skills--under "normal" (baseline) conditions and under conditions where a spring load was applied to the catching hand (thereby changing the dynamics of the skeletomuscular system) it was hoped to provide further clarification of this issue. Traditional force scaling models, in this respect, would predict that maximal closing velocity of the grasp action, and movement time would not be significantly different between a control and a spring-load condition. In contrast, a dynamic system perspective would maintain that spring loading would be compensated for by a change in the rate of shift of the reciprocal command (R-command). The obtained results showed a significant difference for conditions with regard to the maximal closing velocity of the grasp action, the baseline condition being higher than the two spring-load conditions. Furthermore, a significant difference was found for the aperture at moment of catch, the aperture at moment of catch being smaller in the baseline condition than that under the two spring-load conditions. With regard to the temporal variables, no significant differences were obtained. A comprehensive overall explanation of the obtained data in terms of the force scaling models was not realisable. It may be that findings supporting such theories are task specific and that for constrained tasks--such as catching a ball--different underlying organisational principles apply. The lambda model, however, could explain adequately the obtained results. It was concluded that, except for the preparatory phase associated with load compensation before the onset of the movement of the ball, the spatiotemporal structure of the control pattern underlying catching remains the same (invariant) in both baseline and load conditions. Thereby, the spatiotemporal structure of the resulting movement changes under the influence of the load and thus is not the same for load and baseline condition.     

The generalized optic acceleration cancellation theory of catching.

The generalized optic acceleration cancellation (GOAC) theory of catching proposes that the path of a fielder running to catch a ball is determined by the attempt to satisfy 2 independent constraints. The 1st is to keep the angle of elevation of gaze to the ball increasing at a decreasing rate. The 2nd is to control the rate of horizontal rotation necessary to maintain fixation on the ball. Depending on the lateral velocity of the ball relative to the fielder, this rate may be zero or constant at a negative or positive value. The authors show that a simulated fielder implementing the GOAC strategy follows a path indistinguishable from that of real fielders running to catch balls thrown on the same trajectories. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Functional asymmetries in the quality of handwriting movements: A kinematic analysis.

Writing hand preference is a prominent functional asymmetry, but biomechanical factors may also contribute to any kinematic differences in the quality of handwriting movements performed by either hand. Eighteen dextral participants used a noninking pen with their right or left hand to write cursive letter l, inverted ls, and their mirror images (to control for biomechanical differences) on a graphics tablet. Kinematic analysis of the scaling, consistency, efficiency, and shape of writing stroke trajectories revealed functional asymmetries between hands. The right hand was faster and produced more efficient strokes, which were of more consistent length, duration, and peak velocity. Differences between hands do not simply reflect biomechanical factors; therefore, the documentation of any functional asymmetries may allow their subsequent use as markers of underlying pathology in conditions such as schizophrenia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Postdictors of eyewitness errors: Can false identifications be diagnosed?

Eyewitness researchers have "postdicted" identification accuracy using witness confidence (S. L. Sporer, S. Penrod, D. Read, & B. Cutler, 1995), response latency (S. L. Sporer, 1993, 1994), and endorsement of statements consistent with using relative versus absolute judgment strategies (D. Dunning & L. B. Stem, 1994; R. C. L. Lindsay & K. Bellinger, 1999). All of these measures were collected from 321 introductory psychology students who had viewed a staged crime and completed a lineup identification task. Some participants received feedback after identification (G. L. Wells & A. L. Bradfield, 1998). Lineup fairness was also used as a postdictor of eyewitness accuracy. Discriminant function analysis indicated that 75.2% of choosers and 63.0% of nonchoosers were correctly classified. Decision time and lineup fairness were the best postdictors of accuracy. The implications for postdicting real eyewitness decisions are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Negative affect and interpersonal rejection among prison inmates in a therapeutic community: A social relations analysis.

The authors used D. A. Kenny's (1994a) social relations model to examine J. C. Coyne's (1976b) interpersonal theory of depression among a clinical sample of well-acquainted prison inmates. Members of 12 therapy groups (N/&=/&142) diagnosed with a substance abuse disorder completed a self-report measure of depression and anxiety and indicated their desire to interact with other group members. There was both consensus about which group members were rejected and individual differences in the participants' reported desire for future interaction with other group members. Those reporting high levels of depressive negative affect were most likely to be rejected. Those lowest in positive affect indicated the least desire for future interaction with others. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Gender differences in learning and memory after pediatric traumatic brain injury.

Thirty boys and 30 girls who sustained a traumatic brain injury (TBI) were evaluated within 1 year postinjury with the California Verbal Learning Test--Children's Version (CVLT-C; D. C. Delis, J. H. Kramer, E. Kaplan, & B. A. Ober, 1994). Boys had statistically significantly lower performance on the CVLT-C than girls in the absence of statistically significant group differences on various demographic and neurological variables. Although the effect size for this difference was modest (η=.09), gender accounted for a statistically significant amount of the variance (5%) in CVLT-C scores in addition to effects of injury severity and age. It is concluded that male gender is associated with an increased risk for retrieval deficits after pediatric TBI, possibly because of reduced speed or efficiency of information processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Latent growth modeling of the relationship between depressive symptoms and substance use during adolescence.

To explicate the nature of the relationship between depressive symptoms and substance use, the authors conducted research that incorporated both individual and group approaches and utilized longitudinal data across development. Multiple-group latent growth curve models were used to assess specific dimensions (cross-sectional and longitudinal correlation, within-individual change, and movement off developmental trajectories) of the relationship between depressive symptoms and substance use during adolescence and how this relationship differs by gender. Annual survey data from 8th through 11th grade were provided by 441 girls and 510 boys in the Raising Healthy Children project (E. C. Brown, R. F. Catalano, C. B. Fleming, K. P. Haggerty, & R. D. Abbott, 2005). Levels of depressive symptoms and substance use in early adolescence were positively associated for alcohol, marijuana, and cigarette use for girls, but only for marijuana use for boys. Individual changes in depressive symptoms and substance use across adolescence were positively associated for each type of substance use. Evidence was also found for positive association between episodic expressions of depressive symptoms and alcohol use that fell outside developmental trajectories. Predictive relationships across constructs were not found, with the exception of higher level of depressive symptoms in early adolescence predicting less increase in alcohol use. (PsycINFO Database Record (c) 2010 APA, all rights reserved)