动觉监督早期介入对动作技能形成的影响

通过人工动作技能项目和典型职业操作技能项目的训练活动,研究了动觉监督早期介入对动作技能形成的影响,结果表明早期进行动觉监督训练可以更为充分、有效地发挥动觉监督的作用,提高动作技能形成的成绩和效率。据此讨论了“视觉为主转化为动觉为主”监督机制观点的局限性,认为自觉的职业操作技能训练活动无须遵循这一结论;提出了含有动觉训练的职业操作技能训练模式。     

Discrimination of direction of movements in pigeons following previous experience of motion/static discrimination

Two experiments examined pigeons' discrimination of directional movement using pictorial images shown on computer monitors. Stimuli consisted of the movement of a bird against a stationary background or the movement of the background behind a stationary bird. In Experiment 1, pigeons were trained to discriminate either leftward or rightward motion of either the bird or the background from stationary frames drawn from the same movies. The background-discrimination group acquired the discrimination faster than the bird-discrimination group. In Experiment 2, transfer of the discrimination from the task of Experiment 1 to a discrimination between motion directions was examined. Most of the pigeons learned this discrimination rapidly, whereas in a pilot study in which direction discrimination was trained without previous static/movement discrimination, learning was poor. It appears that an experimental history of movement against stationary discrimination promoted the pigeons' learning of the directional motion discrimination.     

Perceiving the inertial properties of actions in anticipation skill

Inertial properties of throwing or striking actions constrain action outcomes, but their role in anticipation skill has not been investigated yet. Therefore, the aim of this study was to systematically investigate the effect of inertial constraints on anticipation skill. Fifteen semi-professional and fifteen novice soccer players were tasked with determining the kick direction of penalty kicks occluded at 160 ms, 80 ms before ball-foot contact, at ball-foot contact, or 80 ms after ball-foot contact. The inertial constraints were manipulated by loading the kicking leg with a 2.25 kg weight around the shank of the kicking leg and were compared with unloaded kicks. Anticipation accuracy of kick direction, response time, and decision confidence were recorded. It was found that loaded kick directions were anticipated more accurately, faster, and at earlier occlusion periods than unloaded kicks. The higher accuracy for the loaded kicks was found in the earlier occlusion conditions in experts compared to novices, as were the positive relationships between accuracy and confidence. It was concluded that the perception of the inertial constraints of the kicking action allowed for earlier anticipation of kick direction. It is proposed that accurate perception of the biomechanical property radius of gyrations in the body segments linking proximal to distal towards the kicking foot may provide this information.     

The significance of blushing for fair- and dark-skinned people

Since blushing is difficult to detect in people with dark skin, their experience of blushing may differ fundamentally from people with fair skin. To investigate this issue, cheek temperature and forehead blood flow were measured in 16 Caucasians and 16 Indians during mental arithmetic and singing. Caucasians (particularly females) thought that they blushed more intensely than Indians, and also reported greater self-consciousness when singing. Vascular responses did not differ between groups. However, skin tone moderated the association between vascular responses and ratings of self-consciousness, blushing intensity, blushing propensity and fear of negative evaluation. These findings support the notion that the visibility of blushing influences the nature of emotions experienced in embarrassing social encounters.     

Influence of perceived emotion and gender on social motor coordination

Theorists have long postulated that facial properties such as emotion and sex are potent social stimuli that influence how individuals act. Yet extant scientific findings were mainly derived from investigations on the prompt motor response upon the presentation of affective stimuli, which were mostly delivered by means of pictures, videos, or text. A theoretical question remains unaddressed concerning how the perception of emotion and sex would modulate the dynamics of a continuous coordinated behaviour. Conceived in the framework of dynamical approach to interpersonal motor coordination, the present study aimed to address this question by adopting the coupled-oscillators paradigm. Twenty-one participants performed in-phase and anti-phase coordination with two avatars (male and female) displaying three emotional expressions (neutral, happy, and angry) at different frequencies (100% and 150% of the participant's preferred frequency) by executing horizontal rhythmic left-right oscillatory movements. Time to initiate movement (TIM), mean relative phase error (MnRP), and standard deviation of relative phase (SDRP) were calculated as indices of reaction time, deviation from the intended pattern of coordination, and coordination stability, respectively. Results showed that in anti-phase condition at 150% frequency, MnRP was lower with the angry and the female avatar. In addition, coordination was found to be more stable with the male avatar than the female one when both displaying neutral emotion. But the happy female avatar was found to elicit more stable coordination than the neutral female avatar. These results implied that individuals are more relaxed to coordinate with the female than the male, and the sensorimotor system becomes more flexible to coordinate with an angry person. It is also suggested social roles influence how people coordinate, and individuals attend more to interact with a happy female. In sum, the present study evidenced that social perception is embodied in the interactive behaviour during social interaction.     

Motion tracking of parents’ infant‐ versus adult‐directed actions reveals general and action‐specific modulations

Parents tend to modulate their movements when demonstrating actions to their infants. Thus far, these modulations have primarily been quantified by human raters and for entire interactions, thereby possibly overlooking the intricacy of such demonstrations. Using optical motion tracking, the precise modulations of parents’ infant‐directed actions were quantified and compared to adult‐directed actions and between action types. Parents demonstrated four novel objects to their 14‐month‐old infants and adult confederates. Each object required a specific action to produce a unique effect (e.g. rattling). Parents were asked to demonstrate an object at least once before passing it to their demonstration partner, and they were subsequently free to exchange the object as often as desired. Infants’ success at producing the objects’ action‐effects was coded during the demonstration session and their memory of the action‐effects was tested after a several‐minute delay. Indicating general modulations across actions, parents repeated demonstrations more often, performed the actions in closer proximity and demonstrated action‐effects for longer when interacting with their infant compared to the adults. Meanwhile, modulations of movement size and velocity were specific to certain action‐effect pairs. Furthermore, a ‘just right’ modulation of proximity was detected, since infants’ learning, memory, and parents’ prior evaluations of their infants’ motor abilities, were related to demonstrations that were performed neither too far from nor too close to the infants. Together, these findings indicate that infant‐directed action modulations are not solely overall exaggerations but are dependent upon the characteristics of the to‐be learned actions, their effects, and the infant learners.     

Does Object Height Affect the Dart Throwing Motion Angle during Seated Activities of Daily Living?

Abstract

Complex wrist motions are needed to complete various daily activities. Analyzing the multidimensional motion of the wrist is crucial for understanding our functional movement. Several studies have shown that numerous activities of daily livings (ADLs) are performed using an oblique plane of wrist motion from radial-extension to ulnar-flexion, named the Dart Throwing Motion (DTM) plane. To the best of our knowledge, the DTM plane angle performed during ADLs has not been compared between different heights (e.g. table, shoulder and head height), as is common when performing day-to-day tasks. In this study, we compared DTM plane angles when performing different ADLs at three different heights and examined the relationship between DTM plane angles and limb position. We found that height had a significant effect on the DTM plane angles - the mean DTM plane angle was greater at the lower level compared to the mid and higher levels. A significant effect of shoulder orientation on mean DTM plane angles was shown in the sagittal and coronal planes. Our findings support the importance of training daily tasks at different heights during rehabilitation following wrist injuries, in order to explore a large range of DTM angles, to accommodate needs of common ADLs.     

Determination of visual figure and ground in dynamically deforming shapes

Figure/ground assignment - determining which part of the visual image is foreground and which background - is a critical step in early visual analysis, upon which much later processing depends. Previous research on the assignment of figure and ground to opposing sides of a contour has almost exclusively involved static geometric factors - such as convexity, symmetry, and size - in non-moving images. Here, we introduce a new class of cue to figural assignment based on the motion of dynamically deforming contours. Subjects viewing an animated, deforming shape tended to assign figure and ground so that articulating curvature extrema - i.e., "hinging" vertices - had negative (concave) contour curvature. This articulating-concavity bias is present when all known static cues to figure/ground are absent or neutral in each of the individual frames of the animation, and even seems to override a number of well-known static cues when they are in opposition to the motion cue. We propose that the phenomenon reflects the visual system's inbuilt expectations about the way shapes will deform - specifically, that deformations tend to involve rigid parts articulating at concavities.     

The role of language in memory for actions

Languages differ with respect to how aspects of motion events tend to be lexicalized. English typically conflates MOTION with MANNER, but Japanese and Spanish typically do not. We report a set of experiments that assessed the effect of this cross-linguistic difference on participants' decisions in a similarity-judgment task about scenes containing novel animations as stimuli. In Experiment 1, which required participants to encode the stimuli briefly into memory, we observed a language effect; in Experiment 2, which required participants to analyze the same stimuli, but not remember them, the language effect disappeared. Hence, these experiments reveal a task-dependent effect, which, we argue, points to working memory as the source of the language effect observed in Experiment 1 and, potentially, other experiments that have shown a linguistic relativity effect.     

Assessing pain behaviour of low-back pain patients in real time: concurrent validity and examiner sensitivity

Several systems for measuring pain behaviour have been developed for clinical settings. The present study reports on a real-time system for coding five categories of pain behaviour for low-back pain patients: guarding, touching, sounds, words, and facial expression. Unique features of the system are the use of refined measures of facial expression and integration of the measurements with a standardized physical examination. 176 sub-acute and chronic low-back pain patients underwent a physical examination while their pain behaviour was coded. Concurrent measures of subjective pain, medically-incongruent signs, and independent global ratings of pain behaviour were taken. Analyses indicated that the pain behaviours, particularly guarding and facial expression, varied systematically with the alternative measures, supporting the concurrent validity of the behaviour observation system. While pain behaviours, especially use of words and facial expressions, were significantly associated with the examiners' independent ratings, the strength of the associations suggested that, in the absence of direct training, examiners' performance was relatively poor. Implications for training of clinicians in detecting pain behaviour are discussed.