Revisiting the metacontrast dissociation: Comparing sensitivity across different measures and tasks

In the metacontrast dissociation procedure, presenting a masked shape prime prior to a visible shape target leads to reaction-time effects of the prime in an indirect measure, although participants cannot consciously detect prime shapes in a direct measure (Klotz & Neumann, 1999 Klotz, W. and Neumann, O. 1999. Motor activation without conscious discrimination in metacontrast masking. Journal of Experimental Psychology: Human Perception and Performance, 25: 976–992.  [Google Scholar]). This has been taken as evidence for the processing of unconscious input. The results of the present metacontrast dissociation study indicate that although participants are unable to consciously report the shape of the prime, they can consciously perceive motion between masked primes and visible targets in a hybrid direct/indirect measure (Experiments 1 and 3). This indicates that former tests did not provide an exhaustive measure for residual conscious perception of the prime in the metacontrast dissociation procedure. Further tests, however, reveal that residual motion perception cannot account for performance in the indirect measure (Experiments 2 and 3). Although the results thus leave the conception of processing of unconscious input intact, they may prompt a revision of its criteria.     

Dynamic action in virtual environments: Constraints on the accessibility of action knowledge in children and adults

In a series of three experiments, we probed the accessibility of action knowledge in different versions of a virtual environment (VE) with 7-year-old children and adults. Using a PHANToM^TM haptic interface, participants performed a virtual throwing task in which they tried to propel a ball from a table to hit a target on the ground. In Experiments 1 and 2, the virtual scene was presented on a computer monitor, and, in Experiment 3, it was projected by using a video projector so that the vertical and horizontal dimensions and the spatial location of the VE corresponded to the real-world dimensions. Results indicate that action knowledge is accessible even in a nonimmersive VE, but also suggest that the need to recalibrate perceptual-motor mappings constrains the accessibility of this kind of intuitive knowledge.     

The influence of motor expertise and motor experience on action and actor recognition

Two experiments examined whether different levels of motor and visual experience influence action perception and whether this effect depends on the type of perceptual task. Within an action recognition task (Experiment 1), professional basketball players and novice college students were asked to identify basketball dribbles from point-light displays. Results showed faster reaction times and greater accuracy in experts, but no advantage when observing either own or teammates’ actions compared with unknown expert players. Within an actor recognition task (Experiment 2), the same expert players were asked to identify the model actors. Results showed poor discrimination between teammates and players from another team, but a more accurate assignment of own actions to the own team. When asked to name the actor, experts recognised themselves slightly better than teammates. Results support the hypothesis that motor experience influences action recognition. They also show that the influence of motor experience on the perception of own actions depends on the type of perceptual task.     

The complex challenges of ethical choices by engineers in public service

This paper proposes that engineers in public service are confronted with unavoidable complexity in their ethical considerations. The complexity begins with interactions among venues of ethical choices. Engineers must make ethical choices simultaneously at the individual, professional, organizational and societal levels. These ethical domains often conflict. The complexity also stems from situations in which physical properties may remain stable, but important social, economic, institutional and political conditions can change substantially. The paper proposes that the reflective learning approach of pragmatism can help with these challenging situations. This approach depends upon employing Dewey’s five stage process of inquiry to engage the ethical complexity inherent in the practice of engineering in the public service. An earlier version of this paper was presented at the 2005 conference, Ethics and Social Responsibility in Engineering and Technology, Linking Workplace Ethics and Education, co-hosted by Gonzaga University and Loyola Marymount University, Los Angeles, CA, USA, 9–10 June 2005.     

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.     

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.     

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.     

动、静态视觉信息在真实世界视觉搜索中的作用

真实环境中的视觉搜索是人和动物赖以生存的重要能力。目前的视觉搜索研究多使用静态的观察者和静止的二维搜索对象, 侧重于探究注意在搜索中的作用; 现有的视觉搜索理论模型主要概括了影响搜索的自上而下的注意因素, 而将自下而上影响因素简单归结为影像显著性, 然而在真实环境中, 观察者或搜索对象是可以运动的, 搜索时可利用的视觉信息包括动态光流和静态影像结构信息。已有的视觉识别研究发现这两种信息相结合可以使观察者准确持久地识别场景、事件和三维结构。在现有视觉搜索理论模型中引入两种视觉信息可以较好还原真实环境中的搜索任务。我们提出研究构想和实验方案,探究利用动、静态视觉信息的视觉搜索过程, 从而完善现有的视觉搜索模型。我们认为充分利用环境信息可以提高搜索效率, 且在视觉搜索训练和智能搜索设计等方面有重要的应用价值。