If a target toward which an individual moves his hand suddenly moves, he adjusts the movement of accordingly. Does use visual information on target's velocity to anticipate where will reach target? These questions were addressed in present study. Subjects (N = 6 each 4 experiments) instructed hit disk with rod as soon it appeared screen. Trajectories stationary disks compared those that jumped leftward or rightward subject's started moving screen, and either background rightward. About 110...

Ss were presented with spiders running from left to right at various velocities over a structured background.Motion of the background influenced perceived velocity spider: Motion in opposite direction than spider increased velocity.The position was not by motion.Ss asked hit as quickly possible.Fast higher slow spiders.The same effect found if only differed apparent velocity, induced motion background.The trajectory authors concluded that although is nothing but change time, and are...

One generally has the impression that one feels one's hand at same location as sees it. However, because our brain deals with possibly conflicting visual and proprioceptive information about position by combining it into an optimal estimate of hand's location, mutual calibration is not necessary to achieve such a coherent percept. Does sensory integration nevertheless entail calibration? We asked subjects move their between targets. Blocks trials without any feedback were alternated blocks...

We often encounter pairs of variables in the world whose mutual relationship can be described by a function. After training, human responses closely correspond to these functional relationships. Here we study how humans predict unobserved segments function that they have been trained on and compare predictions differ those made various function-learning models literature. Participants' performance was best predicted polynomial functions generated observations. Further, participants were able...

Abstract In daily life we often interact with moving objects in tasks that involve analyzing visual motion, like catching a ball. To do so successfully track our gaze, using combination of smooth pursuit and saccades. Previous work has shown the occurrence direction corrective saccades leads to changes perceived velocity objects. Here investigate whether such lead equivalent biases interception. Participants had targets their separate sessions either judge targets’ velocities or intercept...

Despite the many studies on visual control of grasping, little is known about how and when small variations in shape affect grasping kinematics. In present study we asked subjects to grasp elliptical cylinders that were placed 30 60 cm front them. The cylinders' aspect ratio was varied systematically between 0.4 1.6, their orientation steps degrees. Subjects picked up all noncircular with a hand approximately coincided one principal axes. probability selecting given axis highest its equal...

To study the strategy in responding to target displacements during fast goal-directed arm movements, we examined how quickly corrections are initiated and vigorously they executed. We perturbed position at various moments before after movement initiation. Corrections perturbations started were with same latency as movement. Subjects also responded a second perturbation reach, even if only separated by 60 ms. The magnitude of correction was minimized respect time remaining until end conclude...

The movements that we make are variable. It is well established at least a part of this variability caused by noise in central motor planning. Here, studied how the random effects planning translate into changes Are independently added to constant mean end point, or do they accumulate over movements? To distinguish between these possibilities, examined repeated, discrete various tasks which output could be decomposed task-relevant and task-irrelevant component. We found all component had...

People can hit rapidly moving balls with amazing precision. To determine how they manage to do so, we explored various factors that could manipulate influenced people's precision when intercepting virtual targets. We found temporal was highest for fast targets subjects were free intercept wherever wished. Temporal much poorer the point of interception specified in advance. Examining responses abrupt perturbations target's motion revealed people adjusted where rather than would target if...

Predictive eye movements targeted toward the direction of ball bounce are a feature gaze behavior when intercepting target soon after it has bounced. However, there is conjecture over exact location which these predictive directed, and whether during this period moving or instead "lies in wait" for to arrive. Therefore, aim study was further examine made hitting bouncing ball. We tracked head 23 novice participants who attempted hit approaching tennis balls virtual environment. The differed...

When we reach out for an object with our hand, transform visual information about the object's position into muscle contractions that will bring digits to position. If a tool transformation is different, because must critical part of object, rather than digits. The difference between motion hand and can be quite large, as when moving computer mouse across table cursor on screen. We examined responses unpredictable perturbations during such movements. People responded quickly changes in...

A decade ago, S. Aglioti, J. F. X. DeSouza, and M. A. Goodale (1995) published an experiment that has had a big influence on the way visual information is thought to control human behavior. Their findings have often been simplified as suggesting action immune perceptual illusions. The current authors critically analyze 4 steps involved in this simplification argue research during last 10 years shown validity of 3 doubtful. They conclude cannot be regarded firm support for 2-visual-systems...

Neurons in different cortical visual areas respond to attributes with latencies. How does this affect the on-line control of our actions? We studied hand movements directed toward targets that could be distinguished from other objects by luminance, size, orientation, color, shape or texture. In some trials, target changed places one at onset hand's movement. determined latency for correcting movement direction new location. show subjects can correct their short all attributes, but responses...