Resolution thresholds for Landolt C's and vernier targets remain the same whether target is stationary or moving with horizontal vertical velocities of up to 2.5°/s foveal presentations lasting 0.1 0.2 s. Oblique motions are tolerated only 1°/s. Because visual pursuit ruled out by randomization direction motion short exposure, it concluded that a retinal image not prerequisite good acuity.

EYE MOVEMENT responses to even the simplest visual stimulus moving in only one dimension an otherwise structureless field are result of activities at several levels. One may distinguish factors operating three somewhat arbitrarily delineated levels: (<i>a</i>) involving mechanical aspects orbit and other levels intervening between initiation nerve impulses designed move eye actual movement; (<i>b</i>) operation what often called psycho-optical reflexes, i. e., mechanisms which make eyes so...

DODGE, who was the first systematically to study and classify various types of eye movements, attached name "saccadic movement" rapid changes in position eyeball which are typically found between fixational pauses during reading. He also observed that movements constituting fast phase opticokinetic vestibular nystagmus have similar characteristics. Most experimenters all voluntary executed absence a moving visual stimulus saccadic, even "pursuit" movement patterns, response stimuli, can be...

1. The adaptation state of a uniformly illuminated patch human cone retina was determined by finding the threshold for small, brief light spot seen flashing in its centre.2. When is increased diameter, first raised, and beyond critical background lowered.3. This interpreted as manifestation excitatory inhibitory interaction stimuli: illumination retinal regions immediate neighbourhood area tested acts to raise level, those further removed lower it.4. which adapting produces inhibition about...

To examine the role of primary visual cortex in visuospatial integration, we studied spatial arrangement contextual interactions response properties neurons alert monkeys and human perception. We found a segregation opposing interactions. At level cortical neurons, excitatory were located along ends receptive fields, while inhibitory strongest orthogonal axis. Parallel psychophysical studies observers showed surrounding target line with similar distribution. The results suggest that V1 can...

Cells in adult primary visual cortex are capable of integrating information over much larger portions the field than was originally thought. Moreover, their receptive properties can be altered by context within which local features presented and changes experience. The substrate for both spatial integration cortical plasticity is likely to found a plexus long-range horizontal connections, formed pyramidal cells, link cells each area distances 6-8 mm. relationship between connections...

One of the fundamental tasks visual cortex is to integrate input from different parts retina, parsing an image into contours and surfaces, then assembling these features coherent representations objects. To examine role primary in integration information, we measured response properties neurons under stimulus conditions. Surprisingly, found that even most conventional measures receptive field (RF) size were not fixed, but could vary depending on contrast foreground–background relationships....

Crist, Roy E., Mitesh K. Kapadia, Gerald Westheimer, and Charles D. Gilbert. Perceptual learning of spatial localization: specificity for orientation, position, context. J. Neurophysiol. 78: 2889–2894, 1997. Discrimination simple visual attributes can improve significantly with practice. We have trained human observers to perform peripherally presented tasks involving the localization short line segments examined location, geometric arrangement stimulus. Several weeks training resulted in...

• Comparison of visual acuity measurements under different conditions (eg, age, refractive error, disease progress, recovery from injury) depends crucially on the scale applied to values minimum angle resolution. Four kinds scales are examined: resolution (MAR) in linear, logarithmic, exponential, and reciprocal measures. To help construct an equal-discriminability for acuity, standard errors mean five retinal locations were determined experimentally two observers. Because ratio error/mean...