Catching With Both Hands: An Evaluation of Neural Cross-Talk and Coordinative Structure Models of Bimanual Coordination

Kelso, Southard, and Goodman (1979) and Marteniuk and MacKenzie (1980) have each proposed a different theoretical model for bimanual coordination. In the model of Kelso et al., a close temporal relationship between the hands in a bimanual task is predicted, even when each hand is required to move different distances. In Marteniuk and MacKenzie's model, separate motor commands are issued so that each limb will arrive simultaneously at the specified movement endpoint, leading to low temporal associations between limbs. In most previous work on bimanual coordination, manual aiming tasks with differing constraints have been used by subjects in individual studies. In this study, the usefulness of existing models for predicting performance in a real-world catching task in which the required movement pattern was constrained by ball flight characteristics was examined. E1even university students caught tennis balls with both hands in the following 3 conditions: Condition 1. Ball projected to the right shoulder area (left hand moved a greater distance than the right); Condition 2. Ball projected to center of the chest area, (both hands moved same distance); and Condition 3. Ball projected to left shoulder area (right hand moved a greater distance). Kinematic data (time to peak velocity, movement initiation time) indicating significant cross-correlations between the left and right limbs in all 3 conditions concurred with the data of Kelso et al. (1979) on manual aiming. Timing appeared to be an essential variable coordinating bimanual interceptive actions. Although the limbs moved at different speeds when each was required to move different distances, times to peak velocity showed strong associations, suggesting the presence of a coordinative structure.     

Set- and Element-Level Stimulus-Response Compatibility Effects for Different Manual Response Sets

In a previous study of two-choice reactions, pairings of spatial stimuli with bimanual presses made on a keyboard and verbal stimuli with unimanual aimed movements made on a display screen showed higher set-level compatibility than the opposite pairings; element-level compatibility (i.e., mapping) effects were also larger for the conditions with high set-level compatibility than for those whose set-level compatibility was low. In the 4 experiments described here, the relevant factors were isolated, allowing the determinants of those compatibility differences to be evaluated in more detail. Forty-eight students participated in Experiment 1, and 24 each in Experiments 2, 3, and 4. The primary determinant of the set-level compatibility variation was whether the response alternatives involved 1 or 2 effectors, but the differences in element-level compatibility effects were determined primarily by the distinction between responding on the screen as opposed to on the keyboard. Implications for models of stimulus-response compatibility are examined.     

False Consensus,Stereotypic Cues,and the Perception of Integrative Potential in Negotiation1

We argue that negotiators' fixed-sum perceptions are caused by the same judgment process that creates false consensus. Bargainers' reliance on their own preferences as a cue to others' preferences leads them to anticipate a fixed-sum conflict. When presented with stereotypic cues, subjects in a negotiating experiment anticipated the variable-sum nature of the task and subsequently realized highly efficient settlements extremely quickly. Surprisingly, even when the party's preferences were unrepresentative of the stereotype, agreements were no less efficient than in the absence of the cue. The implications of these findings for bargaining research and practice are discussed.     

Coordination Dynamics of the Bipedal Galloping Pattern

A motion equation in relative phase was developed that incorporates the spatial-temporal pattern of the bipedal gallop along with the more commonplace patterns of the bipedal jump and walk-run. In 3 experiments, human participants (N = 6 per experiment) simulated the bipedal gait patterns through the rhythmic motions of hand-held pendulums. Predictions of the motion equation for coordination equilibria and their respective degrees of stability were confirmed. In particular, the gallop pattern was less stable than the fundamental in-phase and antiphase patterns but changed in qualitatively similar ways to those gaits as a function of limb asymmetry and movement frequency. The relation between the modeled coordination dynamics and the kinematic characteristics of real bipedal galloping is discussed     

Adult Attachment Styles, the Desire to Have Children, and Working Models of Parenthood

ABSTRACT College students who had yet to marry and begin a family were asked about their desire to have children and their beliefs and expectations about themselves as parents (Study 1) and the characteristics of their prospective children (Study 2). Persons with more avoidant and anxious-ambivalent models of close adult relationships harbored more negative models of parent-hood and parent-child relationships. These findings indicate that working models of parenting and parent-child relationships form well before marriage and the birth of children and that these models are systematically associated with attachment styles in adult relationships. The findings also suggest ways in which insecure attachments between child and parent may be influenced by the caregiver's models of parenting and parent-child relationships.     

Influences of Destructive Personality Information on Decision Making1

This study examined the effects of information about a landlord's personality on juror judgments for a landlord-tenant civil trial. The personality information manipulated was specifically relevant to destructive acts. Alternative versions of witness testimony were used to describe a landlord either high or low on need for power. treating people as objects, and negative life themes. This information strongly influenced aspects of the schema for this case constructed by the individual mock jurors. Destructive personality information caused dislike of the landlord and lowered the credibility of his story. If the landlord treated people as objects, the credibility of the tenant's story and positive evaluations of the tenant increased. Juror judgments about relative fault were strongly shifted by destructive personality information. An empirical model for juror decisions indicated a dynamic interplay of story components and fault judgments.     

Measurement and mismeasurement of mood: recurrent and emergent issues

The affective explosion in psychology has led to tremendous advances in mood measurement. Mood ratings reflect a hierarchical structure consisting of two broad dimensions-Positive Affect and Negative Affect-and multiple specific states. Brief scales have been developed that reliably assess Positive and Negative Affect across different populations and time frames, in both between- and within-subject data. We examine controversies related to (a) the content of these higher order scales and (b) the independence of Positive and Negative Affect. Regarding the latter, we show that Positive and Negative Affect scales remain largely independent across a wide range of conditions, even after controlling for random and systematic error. Finally, there remains little consensus regarding the lower order structure of affect. This lack of a compelling taxonomy has substantially slowed progress in assessing mood at the specific affect level.     

The Shadow of Dunblane

The massacre of sixteen children and their teacher in Scotland, at the Dunblane Primary School, earlier this year, shook the world. Hundreds of thousands of flowers were sent from all over the globe, as a gesture of sympathy and solidarity. Eight months later, the world carries on its normal business, but for the people of Dunblane there can be no return to normality. This article looks at some points raised by the Cullen Report, the Government inquiry into the massacre, particularly the emerging details about the background of the killer, Thomas Hamilton. These details are set alongside Jung's discussion of the Shadow archetype. The article also examines the role of the local churches at the time of the tragedy and thereafter, particularly the Cathedral at the center of Dunblane. The final section looks at some general reactions within the community to the killings.     

Stochastic ordering using the latent trait and the sum score in polytomous IRT models

In a restricted class of item response theory (IRT) models for polytomous items the unweighted total score has monotone likelihood ratio (MLR) in the latent trait. MLR implies two stochastic ordering (SO) properties, denoted SOM and SOL, which are both weaker than MLR, but very useful for measurement with IRT models. Therefore, these SO properties are investigated for a broader class of IRT models for which the MLR property does not hold.In this study, first a taxonomy is given for nonparametric and parametric models for polytomous items based on the hierarchical relationship between the models. Next, it is investigated which models have the MLR property and which have the SO properties. It is shown that all models in the taxonomy possess the SOM property. However, counterexamples illustrate that many models do not, in general, possess the even more useful SOL property.Hemker's research was supported by the Netherlands Research Council, Grant 575-67-034. Junker's research was supported in part by the National Institutes of Health, Grant CA54852, and by the National Science Foundation, Grant DMS-94.04438.