Judgments of reachability are independent of visuomotor adaptation

The furthest distance that is judged to be reachable can change after participants have used a tool or if they are led to misjudge the position of their hand. Here we investigated how judged reachability changed when visual feedback about the hand was shifted. We hoped to distinguish between various ways in which visuomotor adaptation could influence judged reachability. Participants had to judge whether they could reach a virtual cube without actually doing so. They indicated whether they could reach this virtual cube by moving their hand. During these hand movements, visual feedback about the position of the hand was shifted in depth, either away from or toward the participant. Participants always adapted to the shifted feedback. In a session in which the hand movements in the presence of visual feedback were mainly in depth, perceived reachability shifted in accordance with the feedback (more distant cubes were judged to be reachable when feedback was shifted further away). In a second session in which the hand movements in the presence of visual feedback were mainly sideways, for some participants perceived reachability shifted in the opposite direction than we expected. The shift in perceived reachability was not correlated with the adaptation to the shift in visual feedback. We conclude that reachability judgments are not directly related to visuomotor adaptation.     

Self‐Control Inhibits Aggression

Aggression brings tremendous costs to individuals, relationships, and society. Yet, people behave aggressively toward strangers and close others at alarmingly high rates. The current article seeks to unlock part of the mystery of why people behave aggressively. We review evidence that self‐control failure plays an integral role in many acts of aggression and violence. We begin by reviewing theoretical models that emphasize the importance of self‐control processes in understanding aggressive and other criminal behaviors. We also discuss how a theoretical model that originally neglected self‐control processes can be extended to incorporate self‐control theorizing. We then discuss recent empirical evidence (a) showing that self‐control failure is a crucial predictor of aggression toward strangers and romantic partners and (b) identifying the neural processes relevant to the self‐control of aggression. Finally, we review evidence that self‐control processes can also explain why people engage in displaced aggression toward bystanders. By appreciating the importance of self‐control processes, researchers and laypersons can gain a better understanding of why people behave aggressively – and how aggression can be prevented.     

Psychometric functions for detection and discrimination with and without flankers

Recent studies have reported that flanking stimuli broaden the psychometric function and lower detection thresholds. In the present study, we measured psychometric functions for detection and discrimination with and without flankers to investigate whether these effects occur throughout the contrast continuum. Our results confirm that lower detection thresholds with flankers are accompanied by broader psychometric functions. Psychometric functions for discrimination reveal that discrimination thresholds with and without flankers are similar across standard levels, and that the broadening of psychometric functions with flankers disappears as standard contrast increases, to the point that psychometric functions at high standard levels are virtually identical with or without flankers. Threshold-versus-contrast (TvC) curves with flankers only differ from TvC curves without flankers in occasional shallower dippers and lower branches on the left of the dipper, but they run virtually superimposed at high standard levels. We discuss differences between our results and other results in the literature, and how they are likely attributed to the differential vulnerability of alternative psychophysical procedures to the effects of presentation order. We show that different models of flanker facilitation can fit the data equally well, which stresses that succeeding at fitting a model does not validate it in any sense.     

Timing the moment of impact in fast human movements

The reported resolution of timing the moment of impact in fast human movements differs widely depending on the task. Surprisingly, better timing is reported for the demanding task of batting a ball than for the much simpler task of tapping in synchrony with two hands. We wondered whether this is because a sizeable part of timing variability arises from misjudging the distance in the direction of one's own movement, so that moving faster (as the bat does when moving toward a ball) improves timing. We found that moving faster does indeed improve timing in both the above-mentioned tasks. After removing the proposed contribution of misjudging the distance in the direction of one's own movement, we estimated that the remaining standard deviation in timing is just over 6ms for both tasks.     

Parent training in nonviolent resistance for adult entitled dependence

"Adult entitled dependence" is a condition characterized by the extreme dependence of grown children on their family and by levels of dysfunction, seemingly excessive in light of their apparent capacity to function. The family and the dependent adult become involved in an interaction in which the very attempts to alleviate the problem may aggravate it. Parent-training in nonviolent resistance (NVR) is an intervention that has been shown to be helpful to parents of behaviorally disturbed youth. Parent training in NVR offers parents means to shift away from a stance of helplessness toward realistic goals that are accomplishable without the collaboration of their offspring. We report on the parents of 27 entitled dependent grown children who participated in parent training in NVR. Additionally, we present 2 detailed case studies that exemplify the problem and the therapeutic process. Before treatment, the dependent adults were not working or studying, drew heavily on parental services (financial or otherwise), and were resistant to parental attempts to change the situation. Most parents succeeded in overcoming their helplessness and reducing the provision of parental services. In a considerable proportion of cases, the grown children started working or studying or moved to independent lodgings.     

Adolescent marijuana use: screening and ethics

Adolescent marijuana use is an issue of concern to the entire community. The emergence of technology that can identify marijuana use poses questions relating to public health issues such as justification and extension of screening. This article discusses the moral issues relating to surveillance of adolescent marijuana use and postulates a justification for clinical screening.     

The acquisition of mental verbs: A systematic investigation of the first reference to mental state

It is generally recognized that the ability to contemplate and communicate about the knowledge, beliefs, and goals of oneself and others is a benchmark of human cognition. Yet, little is known about the beginnings of this ability, in large measure because methods for accurately assessing very young children's ability have been unavailable. Here we present the results of using a method of convergent analyses of naturally occurring speech to assess the young child's ability to contemplate and communicate about mental state. The first study describes the frequency and function of verbs of mental reference such as think and know in the speech of one child from 2;4 to 4;0. The second examines shorter samples of speech collected from 30 two-year-olds over a 6 month period. Results from both studies suggest that the earliest uses of mental verbs are for conversational functions rather than for mental reference. First attempts at mental reference begin to appear in some children's speech in the second half of the third year. Since most of the children studied exhibited the linguistic knowledge necessary to make reference to mental states, we conclude that the absence of such reference earlier suggests that still younger children lack awareness of such states, or at the very least, an understanding of their appropriateness as topics of conversation.     

Treating nailbiting: a comparative analysis of mild aversion and competing response therapies.

This study compared two methods of treating nail-biting. One method involved the use of a mild aversive stimulus in which subjects painted a bitter substance on their nails, and the other required the subject to perform a competing response whenever they had the urge to bite or found themselves biting their nails. Both methods included self-monitoring of the behaviour, and a third group of subjects performed self-monitoring alone as a control condition. The study lasted four weeks. Twenty-one subjects, seven per group, participated. Both methods resulted in significant improvements in nail length, with the competing response method showing the most beneficial effect. There was no significant improvement for the control group. The competing response condition also yielded significant improvements along other dimensions such as degree of skin damage and subjects own ratings of their control over their habit. These were not seen for the other two conditions. The benefits of this abridged version of Azrin and Nunn's (Behaviour Research and Therapy, 11, 619-628, 1973) habit reversal method in terms of treatment success, use of therapist time and client satisfaction, are discussed.