Comfort constrains graphic workspace: Test results of a 3D forearm model

Human movement performance is subject to many physical and psychological constraints. Analyses of these constraints may not only improve our understanding of the performance aspects that subjects need to keep under continuous control, but may also shed light on the possible origins of specific behavioral preferences that people display in motor tasks. The goal of the present paper is to make an empirical contribution here. In a recent simulation study, we reported effects of pen-grip and forearm-posture constraints on the spatial characteristics of the pen tip's workspace in drawing. The effects concerned changes in the location, size, and orientation of the reachable part of the writing plane, as well as variations in the computed degree of comfort in the hand and finger postures required to reach the various parts of this area. The present study is aimed at empirically evaluating to what extent these effects influence subjects' graphic behavior in a simple, free line-drawing task. The task involved the production of small back-and-forth drawing movements in various directions, to be chosen randomly under three forearm-posture and five pen-grip conditions. The observed variations in the subjects' choice of starting positions showed a high level of agreement with those of the simulated graphic-area locations, showing that biomechanically defined comfort of starting postures is indeed a determinant of the selection of starting points. Furthermore, between-condition rotations in the frequency distributions of the realized stroke directions corresponded to the simulation results, which again confirms the importance of comfort in directional preferences. It is concluded that postural rather than spatial constraints primarily affect subjects' preferences for starting positions and stroke directions in graphic motor performance. The relevance of the present modelling approach and its results for the broader field of complex motor behavior, including the manipulation of tools, is indicated briefly. Received: 9 March 1998 / Accepted: 27 November 1998     

The acquisition of an appetite

Unlike older animals, weanling-age rats do not seek water to drink when they are dehydrated, despite the fact that a physiological sensitivity to dehydration is present very soon after birth. We demonstrate here that the appetitive behaviors needed to approach and obtain water become linked to dehydration only as a result of specific postnatal learning experience. Preventing early experience with dehydration retards the developmental emergence of dehydration-induced, water-oriented behavior in young rats. But a single pairing of water with dehydration can establish an appetitive response. These findings reveal a critical role of early learning in the development of goal-oriented behavior. Such a learning process is potentially characteristic of other behavioral systems, from the most basic appetites to complex motives.     

Forgetting of prior remembering in persons reporting recovered memories of childhood sexual abuse

Case studies of individuals reporting recovered memories of childhood sexual abuse suggest that some overestimate their prior forgetting of the abuse. People reporting recovered or continuous memories of childhood sexual abuse and control subjects reporting no history of abuse participated in two experiments examining this "forgot it all along" phenomenon. Participants in Experiment 1 were more likely to forget that they had previously recalled a studied item if they were cued to think of it differently on two recall tests than if they were cued to think of it in the same way on the two tests. This effect was stronger for recovered-memory participants than for continuous-memory and control participants. In Experiment 2, participants recalled autobiographical events three times over a period of 4 months. Much as in Experiment 1, they underestimated prior remembering when the events had been recalled in a different emotional frame (positive vs. negative) on the previous occasion. This underestimation was more pronounced for recovered-memory participants than for continuous-memory and control participants.     

Analytic preparation: the creation of an analytic climate with patients not yet in analysis

The art and science of beginning an analysis has a life of its own and can be considered in many ways quite apart from its later stages. An incremental path forward is smoothed for patients who are not yet prepared to analyze, and builds eventually into something readily recognizable as an analysis. The term analytic preparation refers to this set of processes. Early on, the analyst is concerned less with facilitating an early replica of an idealized analysis than with facilitating the mutual adaptation of patient and analyst as they begin to negotiate a "thought community." Since analytic preparation is not an entity, it does not neatly overlap in real time with the opening phase as usually described, does not have a discrete beginning or end, and does not abruptly shift mid-stream into analysis proper. Some relations between analytic preparation, analytic interaction, and the interpretation of transference are examined.     

Negotiators' bargaining histories and their effects on future negotiation performance

In 2 studies the authors show that the quality of deals negotiators reach are significantly influenced by their previous bargaining experiences. As predicted, negotiators who reached an impasse on a prior negotiation were more likely either to impasse in their next negotiation or to reach deals of low joint value compared to those who had reached an initial agreement. Notably, the impact of past performance on subsequent deals was just as strong for negotiators who changed partners on the 2nd occasion. Results highlight the role of bargaining histories as significant predictors of negotiation behavior. Moreover, they suggest that, at least in some cases, negotiations should be conceptualized as interrelated exchanges rather than separable incidents.     

Phonological neighborhood density in the picture naming of young children who stutter: preliminary study

The purpose of this study was to assess the effect of phonological neighborhood density on the speech reaction time (SRT) and errors of children who do and do not stutter during a picture-naming task. Participants were nine 3-5-year-old children who stutter (CWS) matched in age and gender to nine children who do not stutter (CWNS). Initial analyses indicated that both CWNS and CWS were significantly faster (i.e., exhibited shorter SRTs) and more accurate on phonologically sparse than phonologically dense words, findings consistent with those found with older children (Newman & German, 2002). Further analyses indicated that talker group differences in receptive language scores weakened these findings. These preliminary findings were taken to suggest that phonological neighborhood density appears to influence the picture-naming speed and accuracy of preschool-aged children. EDUCATIONAL OBJECTIVES: The reader will learn about and be able to: (1) recognize the relevance of examining phonological variables in relation to childhood stuttering; and (2) describe the method of measuring speech reaction times and errors during a picture-naming task as a means of assessing linguistic skills.     

Contingency experiences of 3-month-old children and their relation to later developmental achievements

In this study, the authors investigated the relation between early social contingency experiences and infants' competencies to detect nonsocial contingencies. In this study of 87 three-month-old infants, the authors operationalized early social contingencies as prompt, contingent maternal responses and coded microanalytically on the basis of video-recorded mother-infant interactions. The authors assessed competence to detect nonsocial contingencies by 2 methods: (a) the mobile conjugate reinforcement paradigm, which focuses on detecting contingencies between the infants' actions (kicking) and nonsocial consequences (mobile moving) and (b) the visual expectation paradigm, which focuses on detecting contingencies between 1 event (a smiley face projected on a screen) that was followed by a 2nd event (a complex picture projected on the other side of the screen). The results showed that early social contingencies are related to the competency to detect nonsocial action-consequence contingencies in the mobile conjugate reinforcement paradigm.