What is learned from experience in a probabilistic environment?

Three experiments explored what is learned from experience in a probabilistic environment. The task was a simulated medical decision‐making task with each patient having one of two test results and one of two diseases. The test result was highly predictive of the disease for all participants. The base rate of the test result was varied between participants to produce different inverse conditional probabilities of the test result given the disease across conditions. Participants trained using feedback to predict a patient's disease from a test result showed the classic confusion of the inverse error, substituting the forward conditional probability for the inverse conditional probability when tested on it. Additional training on the base rate of the test result did little to improve performance. Training on the joint probabilities, however, produced good performance on either conditional probability. The pattern of results demonstrated that experience with the environment is not always sufficient for good performance. That natural sampling leads to good performance was not supported. Further, because participants not trained on joint probabilities did, however, know them but still committed the confusion of the inverse error, the hypothesis that having joint probabilities would facilitate performance was not supported. The pattern of results supported the conclusion that people learn all the necessary information from experience in a probabilistic environment, but depending upon what the experience was, it may interfere with their ability to recall to memory the appropriate sample set necessary for estimating or using the inverse conditional probability. Copyright © 2004 John Wiley & Sons, Ltd.     

Estimating the effect of gang membership on nonviolent and violent delinquency: a counterfactual analysis

This study reconsiders the well‐known link between gang membership and criminal involvement. Recently developed analytical techniques enabled the approximation of an experimental design to determine whether gang members, after being matched with similarly situated nongang members, exhibited greater involvement in nonviolent and violent delinquency. Findings indicated that while gang membership is a function of self‐selection, selection effects alone do not account for the greater involvement in delinquency exhibited by gang members. After propensity score matching was employed, gang members maintained a greater involvement in both nonviolent and violent delinquency when measured cross‐sectionally, but only violent delinquency when measured longitudinally. Additional analyses using inverse probability of treatment weights reaffirmed these conclusions. Aggr. Behav. 36:437–451, 2010. © 2010 Wiley‐Liss, Inc.     

Development of Force Adaptation During Childhood

Humans learn to make reaching movements in novel dynamic environments by acquiring an internal motor model of their limb dynamics. Here, the authors investigated how 4- to 11-year-old children (N = 39) and adults (N = 7) adapted to changes in arm dynamics, and they examined whether those data support the view that the human brain acquires inverse dynamics models (IDM) during development. While external damping forces were applied, the children learned to perform goal-directed forearm flexion movements. After changes in damping, all children showed kinematic aftereffects indicative of a neural controller that still attempted to compensate the no longer existing damping force. With increasing age, the number of trials toward complete adaptation decreased. When damping was present, forearm paths were most perturbed and most variable in the youngest children but were improved in the older children. The findings indicate that the neural representations of limb dynamics are less precise in children and less stable in time than those of adults. Such controller instability might be a primary cause of the high kinematic variability observed in many motor tasks during childhood. Finally, the young children were not able to update those models at the same rate as the older children, who, in turn, adapted more slowly than adults. In conclusion, the ability to adapt to unknown forces is a developmental achievement. The present results are consistent with the view that the acquisition and modification of internal models of the limb dynamics form the basis of that adaptive process.     

Why do we need perceptual content?

Most representationalists argue that perceptual experience has to be representational because phenomenal looks are, by themselves, representational. Charles Travis (2004 Travis, C. (2004). The silence of the senses. Mind, 113, 57–94.[Crossref], [Web of Science ®] , [Google Scholar]) argues that looks cannot represent. I argue that perceptual experience has to be representational due to the way the visual system works.     

Neurones miroir, résonance et cognition sociale

Mirror neurons were discovered in the 1990's by cognitive neuroscientists from Parma. How central are mirror neurons in primates, social cognition. Do mirror neurons enable an observer to match the agent's observed movements onto her own motor repertoire? Does this matching enable the observer to represent the agent's intention, as argued by Rizzolatti et al? A positive answer to these questions can't be provided unless one assumme that mirror neurons compute the goal of an action by means of a “forward model” of the perceived action. However, the experimental evidence rather suggests that mirror neurons compute the motor means for achieving the desired goal, in accordance with an “inverse model” of the perceived action.     

宽带宽噪音图片朝向辨识任务上的“反倾斜效应”

本研究探讨宽带宽噪音图片的反倾斜效应及短期训练对其影响。首先,我们测量被试对四个朝向(0°,45°,90°和135°)噪音图片的知觉明显度阈值。然后根据被试的阈值生成图片,让被试完成朝向辨识任务,记录正确率和反应时。结果表明人对倾斜朝向刺激的辨识显著好于主要朝向。并且,被试对所有朝向刺激的辨识经训练后都有显著提高。本研究提示人们对于这种宽带宽噪音图片的辨识能够学习,但是短期的训练不能使反倾斜效应消失。     

The rasch model,the law of comparative judgment and additive conjoint measurement

Relationships between the Rasch model and both the law of comparative judgment and additive conjoint measurement are discussed. The distance between the ability of Persona and the difficult of Itemi is, in the Rasch model, the baseline value corresponding to the probability thata will respond correctly toi, where this probability is interpreted as the area under a logistic curve (which is substantially equivalent to the normal curve) and is thus an application of the law of comparative judgment. Under certain assumptions, the Rasch model is also a special case of additive conjoint measurement and, properly reinterpreted, may be usefully applied in contexts other than individual differences.     

Inverse effectiveness, multisensory integration, and the bodily self: Some statistical considerations

A recent report in Consciousness and Cognition provided evidence from a study of the rubber hand illusion (RHI) that supports the multisensory principle of inverse effectiveness (PoIE). I describe two methods of assessing the principle of inverse effectiveness (‘a priori’ and ‘post-hoc’), and discuss how the post-hoc method is affected by the statistical artefact of ‘regression towards the mean’. I identify several cases where this artefact may have affected particular conclusions about the PoIE, and relate these to the historical origins of ‘regression towards the mean’. Although the conclusions of the recent report may not have been grossly affected, some of the inferential statistics were almost certainly biased by the methods used. I conclude that, unless such artefacts are fully dealt with in the future, and unless the statistical methods for assessing the PoIE evolve, strong evidence in support of the PoIE will remain lacking.