Selection and Planning of Reach to Grasp Actions in the Presence of Competing Action Targets

当计划一个行动时，我们的环境中可能有许多我们可以与之交互的对象。考虑一下和朋友共进午餐，你的水杯、朋友的杯子、番茄酱瓶子、盐瓶都可能成为你行动的潜在目标。以前的研究表明，我们的伸手动作可以转向或远离环境中令人分心的物品，当有令人分心的物品存在时，我们需要更长的反应时间才能到达目标。然而，这些研究中的大多数都使用了指向运动。显然，我们经常需要抓取环境中的物体，但抓取可能会改变我们想要将手臂运送到物体上的方式。例如，你可以指向一个物体上的任何地方，但你需要让你的手掌可用于该物体，才能抓住它。这项拟议研究的主要目标是了解当我们的环境中有多个对象时，我们如何选择和计划抓取动作。这项拟议的研究将使用特殊的摄像头来记录参与者如何在空间中移动手臂，以及使用特殊的手套来记录人的手的形状。在所有的实验中，当另一个物体出现时，参与者必须伸手抓住或指向物体。在第一系列实验中，参与者将在开始运动之前知道他们应该到达什么对象。我们预计他们的手臂路径将受到非目标对象的影响，特别是受位于手掌同一侧的非目标对象的影响。在另一系列实验中，参与者需要在知道目标在哪里之前开始移动。只有当它们开始移动时，它们才会被提示哪个物体是目标。这模仿了我们如何在不确定的条件下或当环境中的信息发生变化时计划我们的行动。我们预计参与者会计划开始移动，这样当他们不确定要移动到哪个对象时，他们的手掌就可以用于两个潜在的对象。在最后一系列实验中，参与者将看到两个大小不同的物体。他们将不得不在不知道哪个物体将成为目标的情况下开始移动。我们将检查他们张开的手有多大，以什么形状。在这一系列实验中，我们还将建立一个模型，预测手在运动早期最终会做出什么样的抓握形状。这项拟议的研究将为我们的大脑如何控制手臂和手的使用提供新的知识。预测抓取运动的模型可以在基于机器人和手势的界面中应用。

When planning an action there can be many objects in our environment that we can interact with. Consider meeting a friend for lunch, your water glass, your friend's glass, the ketchup bottle, the salt shaker could all be potential targets for your action. Previous research has shown that our reaching movements can veer toward or away from distracting items in our environment and we take longer to react to reach to a target in the presence of distracting items. Most of these studies however, have used pointing movements. Clearly we often need to grasp objects in the environment, but grasping may change how we want to transport our arm to the object. For instance you can point anywhere on an object, but you need to make the palm of your hand available to the object to be able to grasp it. The main goal of the proposed research is to understand how we select and plan grasping actions when there are multiple objects in our environment. The proposed research will use special cameras that record how the participant is moving their arm through space, and special gloves that can record the shape of a person's hand. In all experiments, participants will have to reach to grasp or reach to point to objects when another object is present. In the first series of experiments, participants will know what object they are supposed to reach to before they start the movement. We expect that their arm path will be affected by the non-target objects, and in particular, by non-target objects that are on the same side of the palm. In another series of experiments participants will need to start their movement before they know where the target is. Only once they start their movement will they be cued to which object is the target. This mimics how we plan our actions under uncertain conditions or when information changes in our environment. We expect that participants will plan to start their movement so their palm is available to both potential objects when they are not sure what object they will have to move to. In a final series of experiments, participants will be presented with two differently sized objects. They will have to start their movement without knowing which object will be the target. We will examine how big they open their hand and in what shape. In this series of experiments we will also be building a model that predicts what grasping shape the hand will eventually make early in the movement. The proposed research will provide new knowledge on how our brain controls the use of our arm and our hand. The model that predicts grasping movements can have applications in robotics and gesture based interfaces.