A central problem in the study of magnetic sensitivity in animals has been the lack of behavioral techniques sufficiently powerful for the systematic psychophysical work required for an understanding of magnetosensory capacity and of the transduction mechanism. In recent experiments, free-flying honeybees have been conditioned to discriminate the presence and ...

Cats were tested for their ability to follow a dot target which periodically jumps horizontally from side to side. They can learn to perform saccadic tracking of various stimulus frequencies, and often they produce saccades predicting the target displacements. The preferred stimulus frequency for response to synchronize was in the ...

Previous studies indicate that in response to a step-ramp visual target movement, the saccade amplitude approximates target displacement 100 ms before saccade onset. This study examines whether the saccadic system takes target motion into consideration when computing saccadic amplitude, if target movement is seen by the subject before he is ...

The oculomotor reactions have recently attracted increasing attention for diagnostic purposes. This is in line with the view that the oculomotor system is one of the simpler, machine-like sensorimotor systems. This paper presents two examples to demonstrate that the complexity of sensorimotor processing may be higher than expected from the ...

Two experiments have been designed to test whether the saccadic system takes target motion into consideration in computing saccade amplitude. In one experiment, while the subject fixated straight ahead, either a horizontal ramp-step-ramp or a horizontal step-ramp target moved from left to right. After the step, the subject had to ...

Human and monkey saccade amplitude and latency, in response to 12-36 degrees target steps, differed substantially despite nearly identical experimental conditions. On single-step trials, monkeys did not undershoot targets, and latencies were insensitive to stimulus and contextual factors. Human saccades did undershoot, their latency was longer, and both undershoot and ...

Various aspects of saccadic eye-movements are related to stimulus luminance for a small lit stimulus that steps 10 degrees horizontally in complete darkness. The relations depend on whether the stimulus is the target for a foveating saccade, or is the cue for an "anti" saccade which peripheralizes the retinal image ...

When two stimuli are presented in different positions successively at short time intervals saccadic eye movements are usually directed at intermediate positions. This phenomenon of "averaging" of saccadic eye movements has been studied in responses to double-step target displacements in different stimulus conditions. In these conditions isoluminant and isochromatic stimuli ...

Normal subjects seated on a moving cart have been submitted to horizontal linear accelerations in the frontal plane. They were shown an earth-fixed target at a distance of 63 cm before the onset of cart motion, which occurred in total darkness. They were asked to keep their gaze on the ...

In this paper we report on human saccade dynamics in three different experimental paradigms: visual target, remembered target and anti-saccade task. We found that saccades to remembered targets and anti-saccades have strongly reduced peak velocities coupled with markedly increased durations. In addition we observed a considerable degree of asymmetry in ...

Eye position of two macaques and two humans was recorded while they detected the unpredictable dimming of a fixation spot in a dark or a light environment. Fixational saccades often had complex waveforms that resulted from clustering of two or more saccadic displacements with no intervening drift periods. In the ...

It has previously been reported by Smets that there is an increase in the magnitude of the monocular oblique effect when a 70 dB(A), 1 kHz acoustic stimulus is presented contralaterally, but not ipsilaterally, to the viewing eye. This finding was interpreted as one which provided difficulties both for data-driven ...

Two experiments examined the magnitude and direction of the initial saccade to a target that underwent two displacements within 200 msec. When the amplitude of the two target displacements was held constant at 10 deg but the angle of the displacements differed by 45 deg, a small but significant number ...

The ocular following responses elicited by brief unexpected movements of the visual scene were studied in eight rhesus monkeys. Test patterns were random dots except in one experiment when sine-wave gratings were used. Test stimuli were velocity steps of 100-ms duration applied after spontaneous saccades. Two response measures were used: ...

The ocular following responses elicited by brief unexpected movements of the visual scene were studied in 10 rhesus monkeys. Test patterns were either random dots or sine-wave gratings [spatial frequency (Fs) 0.046-1.06 cycles per degree (c/degree)]. Test stimuli were velocity steps [speed (V) 5-400 degrees/s] of 100-ms duration, applied 50 ...

Developmental dyslexics (DDs) and good readers (GRs) were tested on measures of interhemispheric coordination. All subjects (ages 16 to 47) demonstrated normal oculomotor control and visual acuity, prior to testing. Subjects were instructed to track three different point-light source patterns (single stimulus in one hemifield, dual stimuli in one hemifield ...

The test/retest variability in different regions of the visual field were evaluated in six commercially available automated threshold static perimeters using normal volunteers. Three of the devices were projection perimeters (Squid, Octopus 500, Humphrey Field analyzer) and three of them used light-emitting diode stimuli (Dicon 2000, Fieldmaster 50, Digilab 350). ...

The retinotectal connections of developing Rana tadpoles and froglets have been studied using light-pipe techniques to directly assay the pattern of the projection from the retina to the tectum. The projection site of the retina surrounding the optic nerve head was determined at two different stages of development (late larval ...

The responses of E-cells, basilar pyramidal cells, of the electrosensory lateral line lobe (ELLL) were studied in normal animals (Apteronotus leptorhynchus) and in fish in which a component of the descending input from the midbrain n. praeeminentialis to the ELLL was interrupted by lesions or by application of local anesthetics. ...

The configuration and extension of enhancement and suppression zones were compared with the configuration and extension of on- and off-response zones across the receptive field of simple cells in cat striate cortex. The enhancement and suppression zones were determined by a dual-stimulus technique where a stationary flashing light slit produced ...

The basic conditions and stimulus parameters of the paradigm usually used to study visual field-hemisphere differences are reviewed. An argument is presented that a majority of published reports using this paradigm are, in fact, the same basic experiment. The similarity of many parameters over experiments constitutes a set of effects ...

The activity of 53 antidromically identified abducens motoneurons was analyzed in alert cats during spontaneous and vestibular induced eye movements. Conduction velocities ranged from 13 to 70 m/s and all motoneurons increased their discharge rates with successive eye positions in the abducting direction. Motoneurons were recruited from -19 degrees to ...

When confronted with randomly presented targets demanding change in mean visual direction (version of 4.5-7 deg) as well as a change in vergence (1.5-2.5 deg) both naive and experienced subjects can make short-latency saccades which differ markedly and appropriately in the excursion of the two eyes, and which thereby achieve ...

Three experiments examined whether age and sex differences in pedestrian accidents might be partly attributable to differences in the visual perception of peripheral stimuli. Primary schoolchildren and adults responded individually to the presentation of lights at retinal eccentricities of 2 degrees, 20 degrees and 40 degrees. Experiments 1 and 2 ...

Sensitivity for detecting visual signals distributed at various locations throughout the visual field was studied in 16 male subjects who were all exposed to two degrees of ambient heat (91 degrees F/61% RH; 55 degrees F/35% RH) while wearing the Army chemical protective clothing system; also to 70 degrees F/35% ...

The detection of coherent movement in stroboscopically (100 Hz) displayed moving random checkerboard ("Julesz-") patterns is studied psychophysically for eccentricities up to 48 degrees in the temporal visual field. Starting from the assumption that the studied visual subsystem consists of ensembles of 'bilocal' movement detectors ("Reichardt-detectors"), the parameters of these ...

Properties of gain adaptivity in the saccadic system were studied. Subjects had to track a target which moved in single or double steps. The first target step which elicited the primary saccade had an amplitude in the range of 8-16 deg. The primary saccade triggered a further target displacement of ...

Involuntary eye movements were recorded during threshold detection tasks under various experimental conditions. The data were analyzed for interdependencies between stimulus parameters, detection performance, and oculomotor behaviour. The data demonstrate that under certain conditions, saccadic parameters are adaptive to specific stimulus properties. Further, the data suggest that for stationary patterns ...

Visual suppression accompanying voluntary saccades and eyeblinks was measured for a range of amplitudes of both. Saccade amplitudes varied from 2 to 32 degrees and blink amplitudes varied from a slight movement to a full closure of the eye. In every case, thresholds for detecting full-field luminance decrements were determined ...

A neotropical treefrog, Smilisca sila, exhibits an unusual ability to synchronize its calling with that of neighbors such that calls often overlap temporally. Call playback experiments measured the latency to evoked calling in response to one-note and two-note mating calls. Approximately one-half of the responses overlapped the one-note stimulus call, ...

The perception of the eccentricity of a suprathreshold light flash (III/4e) presented in a Goldmann perimeter was measured in four ophthalmologically normal observers and three young observers with retinitis pigmentosa (RP). The task was to indicate the perceived distance from central fixation of each light flash by making a mark ...

Single unit activity was monitored in the prelunate gyrus of monkeys trained to execute or suppress goal-directed saccades to a peripheral target in the presence or absence of a central fixation spot. Throughout the experiments in the dimming paradigm was used. We observed the previously reported spatially selective enhancement of ...

Saccades are the rapid eye movements used to change visual fixation. Normal saccades end abruptly with very little postsaccadic ocular drift, but acute ocular motor deficits can cause the eyes to drift appreciably after a saccade. Previous studies in both patients and monkeys with peripheral ocular motor deficits have demonstrated ...

Information Theory has been applied to produce estimates of how valuable each stimulus location on the Friedmann Visual Field Analyser mk. II is in detecting early glaucomatous visual field defects. The results indicate that stimuli in the superior arcuate region of the visual field and in the inferior nasal quadrant ...

Five experiments were conducted to examine duration of visible persistence in sequences of stimuli. The basic display consisted of a point that stepped around a circular path on the face of an oscilloscope. Observers estimated the number of points seen simultaneously. Results were compared with a control condition in which ...

Three experiments investigating the basis of induced motion are reported. The proposition that induced motion is based on the visual capture of eye-position information and is therefore a subject-relative, rather than object-relative, motion was explored in the first experiment. Observers made saccades to an invisible auditory stimulus following fixation on ...

This study examines whether selective attention can influence sensory-discriminative aspects of nociception in humans and monkeys trained to detect innocuous and noxious thermal stimuli. Human subjects had two contact thermodes positioned bilaterally above the upper lip. Upon trial initiation both thermodes heated to either 39 degrees C, an innocuous warm ...

When letters and words are presented tachistoscopically, material from the right visual field (RVF) can be reported more accurately than that from the left visual field (LVF). The RVF superiority may reflect either left hemispheric dominance for language or directional scanning. Previous studies have deliberately focused on the cerebral asymmetry ...

The thermal sensitivity of three humans and two rhesus monkeys was measured behaviorally, using the "yes-no" paradigm of the Theory of Signal Detection. The aim was to evaluate the monkey's thermal-sensing system as a model for that of humans. Three of the principal variables of human thermal sensations--rate of the ...

First saccade responses to sudden presentations of a target/nontarget stimulus consisting of green and red spots of light have been investigated. This paradigm, which avoids certain ambiguities present in earlier experiments with identical double stimuli, leads to remarkably similar conclusions. We found, again, that the saccadic system had short-latency compromising ...

Multi-flash campimetry is a computer-implemented psychophysical technique that allows a rapid and extensive assessment of visual flicker sensitivity. Multi-flash field maps generated from the data typically reveal the presence of 'islands' of degraded temporal resolution in multiple sclerosis (MS) patients, but not in normal control observers. These distinct 'islands' presumably ...

Practitioners of the mindfulness form of Buddhist meditation were tested for visual sensitivity before and immediately after a 3-mo. retreat during which they practiced mindfulness meditation for 16 hr. each day. A control group composed of the staff at the retreat center was similarly tested. Visual sensitivity was defined in ...

The altered feedback technique is very suited to display nonlinearities of the human smooth pursuit system. In fact, when the gain of the retinal feedback path is raised, for the horizontal channel, above its normal unitary negative value, a threshold is met beyond which sustained horizontal self-excited smooth oscillations of ...

The paper deals with the initiation of visually guided saccades, in order to break down the saccadic reaction time into functionally different periods of time. It takes into account that spatial processing of information is so basic that modelling of saccadic control properties should include spatio-temporal arrangements. The output signal ...

Earlier studies using visual double stimuli along the horizontal axis have revealed a strong averaging tendency in the saccadic system. This study shows averaging also for equally eccentric double stimuli with a modest difference in direction (delta phi = 30 deg). When the difference is enlarged (delta phi = 90 ...

The influence of the predictive adaptability on saccades was studied in 20 normal subjects ranging in age from 18 to 43 years. The average velocity of random and constant saccades showed almost the same results. The maximum velocity of constant saccades was slightly faster than that of the random saccades. ...

Monkeys were trained to fixate a small spot of light (fixation spot) and to saccade to a peripheral target if and only if the fixation spot was turned off. If the offset of the fixation spot preceded the onset of the peripheral target by a temporal gap of more than ...

Peak velocity of saccade, maximum velocity of smooth pursuit, and peak velocity of slow phase of vestibular and optovestibular nystagmus were measured three times daily on three separate days in 6 healthy subjects in order to estimate the intra-individual variation of the results of oculomotor tests. Analysis of variance revealed ...

Two studies examined perception of briefly presented (100-msec.) strings of letters. In Study One, 20 subjects were presented horizontal 5-letter strings in the left, central, and right visual fields. These were compared with 5-letter vertical strings presented centrally in the lower, central, and upper visual fields. Similar within-string patterns were ...

1. Horizontal gratings flashed for 20 ms were used to compare visual contrast sensitivity during horizontal saccades with sensitivity during normal vision, at three luminance levels, 4 X 10(2), 4 X 10(-2), and 4 X 10(-4) cd/m2. 2. Greatest sensitivity loss during saccades was found at low spatial frequencies. There ...