The structure of tradeoffs in model building

Despite their best efforts, scientists may be unable to construct models that simultaneously exemplify every theoretical virtue. One explanation for this is the existence of tradeoffs: relationships of attenuation that constrain the extent to which models can have such desirable qualities. In this paper, we characterize three types of tradeoffs theorists may confront. These characterizations are then used to examine the relationships between parameter precision and two types of generality. We show that several of these relationships exhibit tradeoffs and discuss what consequences those tradeoffs have for theoretical practice. John Matthewson and Michael Weisberg have contributed equally to this paper.     

Infants’ cortical processing of biological motion configuration – A fNIRS study

Biological motion perception is a key component of action perception contributing to social cognition in crucial ways. Contemporary neuroimaging studies show that biological motion is processed differently in the human brain from other types of motion. In particular, the right posterior Superior Temporal Sulcus (rpSTS), an area known for its central role in social perception, has been consistently associated with the perception of biological motion in the mature brain. By contrast, most findings investigating the development of biological motion perception in infancy come from behavioral studies, and far less is known regarding the right STS’ role in processing biological motion.The current study used fNIRS to measure brain activation to biological motion in the rSTS region of 7–8-month-old infants. Infants were presented with two conditions: an approaching coherent motion of a person walking (coherent point-light-walker, PLW); and a spatially scrambled version of this display, where the global configuration of a person walking was disrupted (scrambled PLW).We found a functional activation, i.e., a significant increase in HbO₂ concentration in relation to baseline, in the right middle-posterior temporal cortex only when infants viewed the coherent point-light-walker. This activation statistically differed from the scrambled point-light-walker, and no significant activations were found for viewing the scrambled motion.Our study adds evidence pointing to rSTS’ sensitivity to the global human configuration in biological motion processing during infancy. The rSTS seems thus to become functionally specialized in biological motion configuration as early as at 7–8 months of age.     

运动觉、布局无关运动与路径整合

路径整合是空间导航的一个重要子领域。本研究采用了一种三角形完成任务的新变式来研究路径整合问题，发现在剥夺被试的视觉输入的前提下，去除被试部分运动觉后，其绩效有不同水平的下降；同时还发现在编码过程中与路径布局无关的不同方向旋转间并无显著性差异。此外，由于本研究是在室外空间中所做的现场研究，故得到的结果优于室内所做的经典研究，进而验证了前人的一个猜测。     

The perception of biological and mechanical motion in female fragile X premutation carriers

Previous studies reported impaired visual information processing in patients with fragile X syndrome and in premutation carriers. In this study, we assessed the perception of biological motion (a walking point-light character) and mechanical motion (a rotating shape) in 25 female fragile X premutation carriers and in 20 healthy non-carrier controls. Stimuli were moving stimulus dots embedded among a cloud of noise dots. Sensitivity (d′) for motion detection was determined. Emotional symptoms were assessed by Hamilton’s depression and anxiety rating scales. Results revealed that the premutation carriers displayed lower sensitivities for biological and mechanical motion relative to the non-carriers. This deficit was more pronounced in the case of biological stimuli. The premutation carriers displayed higher depression and anxiety scores relative to the non-carriers. Higher depression, but not anxiety, scores were associated with decreased sensitivity for biological, but not mechanical, motion in the carrier group. These results suggest that motion perception deficits are detectable in fragile X premutation carriers, and that the impairment of biological motion perception is associated with depressive symptoms.     

Auditory stimulation affects apparent motion1

Abstract: In two experiments, we investigated how the number of auditory stimuli affected the apparent motion induced by visual stimuli. The multiple visual stimuli that induced the apparent motion on the front parallel plane, or in the depth dimension in terms of the binocular disparity cue, were accompanied by multiple auditory stimuli. Observers reported the number of visual stimuli (Experiments 1 and 2) and the displacement of the apparent motion that was defined by the distance between the first and last visual stimuli (Experiment 2). When the number of auditory stimuli was more/less than that of the visual stimuli, observers tended to perceive more/less visual stimuli and a larger/smaller displacement than when the numbers of the auditory and visual stimuli were the same, regardless of the dimension of motion. These results suggest that auditory stimulation may modify the visual processing of motion by modulating the spatiotemporal resolution and extent of the displacement.     

手的拦截运动的速度伴随效应及影响因素

对手的拦截运动的理论假设、速度伴随效应及其影响因素进行了总结和分析。指出:(1)“速度伴随效应”的机制可能在于补偿反应延迟、维持必需的注视时间、对即时运动信息的利用或时间-准确性权衡;(2)手的拦截运动指标受目标运动方向、先前任务、练习、目标大小、运动表征和策略以及双眼线索等因素的影响;(3)对拦截运动的进一步研究可在统一理论解释的基础上进行,克服研究方法和范围的局限。     

From body motion to cheers: Speakers’ body movements as predictors of applause

Appearance cues and brief displays of behavior are related to people’s personality, to their performance at work and to the outcomes of elections. Thus, people present themselves to others on different communication channels, while their interaction partners form first impressions on the basis of the displayed cues. In the current study we examined whether people are able to read information from politicians’ body motion. For a rating experiment we translated short video clips of politicians giving a speech into animated stick-figures and had these animations rated on trustworthiness, dominance, competence and the Big Five personality dimensions. Afterwards we correlated the ratings with the applause and the hecklings that the speakers received throughout their entire speech. This revealed that speakers whose body movements were perceived as high on dominance, as high on extraversion and as low on agreeableness received more applause. Although the results obtained need support from additional studies they indicate that body motion is an informative cue in real life settings.     

Developmental changes in children's understanding of horizontal projectile motion

This study investigated 5‐ to 13‐year‐old children's performance in solving horizontal projectile motion problems, in which they predicted the trajectory of a carried object released from a carrier in three different contexts. The results revealed that 5‐ and 8‐year‐olds' trajectory predictions were easily distracted by salient contextual features (e.g. the relative spatial locations between objects), whereas a proportion of 11‐ and 13‐year‐olds' performance suggested the engagement of the impetus concept in trajectory prediction. The impetus concept is a typical misconception of inertial motion that assumes that motion is caused by force. Children's performance across ages suggested that their naïve knowledge of projectile motion was neither well‐developed and coherent nor completely fragmented. Instead, this study presented the dynamic process in which children with age gradually overcame the influences of contextual features and consistently used the impetus concept across motion problems.