Temporal characteristics of depth perception from motion parallax were examined by modulating parallax intermittently while observers moved their head side to side. In Experiment 1, parallax of a fixed value was introduced only for the central 1/6 to 5/6 portion of each component head movement. It was found that the perceived depth was proportional to the temporal average of parallax-specified ...

A seven point locomotion scoring scale, ranging from 0=normal locomotion to 6=unable to stand or move, has been developed. To test the between and within observer reliability of the scale, 65 movie clips of sheep with normal and varying degrees of abnormal locomotion were made. Three observers familiar with sheep locomotion were trained to read the movie clips. Thirty clips were randomly select...

Recent years have seen rapid developments in the field of remote eye tracking. Whereas only a few years ago the standard in eye tracking was for systems to be intrusive, i.e. they either required the user’s head to be fixated or equipment to be mounted on the user’s head, systems have now evolved to the point where the user can move freely in front of the system (within certain limits), and goo...

Vision influences behavior, but ongoing behavior also modulates vision in animals ranging from insects to primates. The function and biophysical mechanisms of most such modulations remain unresolved. Here, we combine behavioral genetics, electrophysiology, and high-speed videography to advance a function for behavioral modulations of visual processing in Drosophila. We argue that a set of motio...

Relative image motion resulting from active movement of the observer could potentially serve as a powerful perceptual cue, both for segmentation of object boundaries and for depth perception. To examine the perceptual role of motion parallax from shearing motion, we measured human performance in three psychophysical tasks: segmentation, depth ordering, and depth magnitude estimation. Stimuli co...

Although visual input is egocentric, at least some visual perceptions and representations are allocentric, that is, independent of the observer's vantage point or motion. Three experiments investigated the visual perception of three-dimensional object motion during voluntary and involuntary motion in human subjects. The results show that the motor command contributes to the objective perception...

When shifting gaze to foveate a new target, humans mostly choose a unique set of eye and head movements from an infinite number of possible combinations. This stereotypy suggests that a general principle governs the movement choice. Here, we show that minimizing the impact of uncertainty, i.e., noise affecting motor performance, can account for the choice of combined eye-head movements. This op...

The head movement of a walking pigeon Columba livia is characterized by two alternating phases, a thrust phase and a hold phase. While the head is rapidly thrust forward during the thrust phase, it has been shown repeatedly that it remains virtually motionless with respect to translation along a horizontal axis (roll axis) during the hold phase. It has been shown that the stabilization during t...

Although the eyes and head can potentially rotate about any three-dimensional axis during orienting gaze shifts, behavioral recordings have shown that certain lawful strategies--such as Listing's law and Donders' law--determine which axis is used for a particular sensory input. Here, we review recent advances in understanding the neuromuscular mechanisms for these laws, the neural mechanisms th...

When people perform a task as part of a joint action, their behavior is not the same as it would be if they were performing the same task alone, since it has to be adapted to facilitate shared understanding (or sometimes to prevent it). Joint performance of music offers a test bed for ecologically valid investigations of the way non-verbal behavior facilitates joint action. Here we compare the ...