Eye Movement Research Papers - Academia.edu (original) (raw)

Many current neurophysiological, psychophysical, and psychological approaches to vision rest on the idea that when we see, the brain produces an internal representation of the world. The activation of this internal representation is... more

Many current neurophysiological, psychophysical, and psychological approaches to vision rest on the idea that when we see, the brain produces an internal representation of the world. The activation of this internal representation is assumed to give rise to the experience of seeing. The problem with this kind of approach is that it leaves unexplained how the existence of such a detailed internal representation might produce visual consciousness. An alternative proposal is made here. We propose that seeing is a way of acting. It is a particular way of exploring the environment. Activity in internal representations does not generate the experience of seeing. The outside world serves as its own, external, representation. The experience of seeing occurs when the organism masters what we call the governing laws of sensorimotor contingency. The advantage of this approach is that it provides a natural and principled way of accounting for visual consciousness, and for the differences in the ...

Decisions about the visual world can take time to form, especially when information is unreliable. We studied the neural correlate of gradual decision formation by recording activity from the lateral intraparietal cortex (area LIP) of... more

Decisions about the visual world can take time to form, especially when information is unreliable. We studied the neural correlate of gradual decision formation by recording activity from the lateral intraparietal cortex (area LIP) of rhesus monkeys during a combined motion-discrimination reaction-time task. Monkeys reported the direction of random-dot motion by making an eye movement to one of two peripheral choice targets, one of which was within the response field of the neuron. We varied the difficulty of the task and measured both the accuracy of direction discrimination and the time required to reach a decision. Both the accuracy and speed of decisions increased as a function of motion strength. During the period of decision formation, the epoch between onset of visual motion and the initiation of the eye movement response, LIP neurons underwent ramp-like changes in their discharge rate that predicted the monkey's decision. A steeper rise in spike rate was associated with ...

Immediately following an event at a peripheral location there is facilitation for the processing of other stimuli near that location. This is said to reflect a reflexive shift of attention towards the source of stimulation. After... more

Immediately following an event at a peripheral location there is facilitation for the processing of other stimuli near that location. This is said to reflect a reflexive shift of attention towards the source of stimulation. After attention is removed from such a peripheral location, there is then delayed responding to stimuli subsequently displayed there. This inhibitory aftereffect, first described in 1984 and later labeled 'inhibition of return (IOR)', encourages orienting towards novel locations and hence might facilitate foraging and other search behaviors. Since its relatively recent discovery, IOR has been the subject of intensive investigation, from many angles and with a wide variety of approaches. After describing the seminal contribution of Posner and Cohen ('Who'), this review will discuss what causes IOR and, once initiated, what effects IOR has on subsequent processing ('What'). The time course ('When') and spatial distribution ('Where') of IOR, and what is known about IOR's neural implementation ('How') and functional significance ('Why') are also discussed.

Objectives: Electrical potentials produced by blinks and eye movements present serious problems for electroencephalographic (EEG) and event-related potential (ERP) data interpretation and analysis, particularly for analysis of data from... more

Objectives: Electrical potentials produced by blinks and eye movements present serious problems for electroencephalographic (EEG) and event-related potential (ERP) data interpretation and analysis, particularly for analysis of data from some clinical populations. Often, all epochs contaminated by large eye artifacts are rejected as unusable, though this may prove unacceptable when blinks and eye movements occur frequently.Methods: Frontal channels are often used as reference signals to regress out eye artifacts, but inevitably portions of relevant EEG signals also appearing in EOG channels are thereby eliminated or mixed into other scalp channels. A generally applicable adaptive method for removing artifacts from EEG records based on blind source separation by independent component analysis (ICA) (Neural Computation 7 (1995) 1129; Neural Computation 10(8) (1998) 2103; Neural Computation 11(2) (1999) 606) overcomes these limitations.Results: Results on EEG data collected from 28 normal controls and 22 clinical subjects performing a visual selective attention task show that ICA can be used to effectively detect, separate and remove ocular artifacts from even strongly contaminated EEG recordings. The results compare favorably to those obtained using rejection or regression methods.Conclusions: The ICA method can preserve ERP contributions from all of the recorded trials and all the recorded data channels, even when none of the single trials are artifact-free.

The 1968 Rechtschaffen and Kales (R & K) sleep scoring man- ual was published 15 years after REM sleep was discovered. Advances in the ensuing 28 years warranted a re-look at visual scoring of sleep stages. This paper describes the work... more

The 1968 Rechtschaffen and Kales (R & K) sleep scoring man- ual was published 15 years after REM sleep was discovered. Advances in the ensuing 28 years warranted a re-look at visual scoring of sleep stages. This paper describes the work of the AASM Visual Scoring Task Force, including methodology, a literature review and the rationale behind the new rules.

The neural events associated with visually guided reaching begin with an image on the retina and end with impulses to the muscles. In between, a reaching plan is formed. This plan could be in the coordinates of the arm, specifying the... more

The neural events associated with visually guided reaching begin with an image on the retina and end with impulses to the muscles. In between, a reaching plan is formed. This plan could be in the coordinates of the arm, specifying the direction and amplitude of the ...

We studied the functional organization of human posterior parietal and frontal cortex using functional magnetic resonance imaging (fMRI) to map preparatory signals for attending, looking, and pointing to a peripheral visual location. The... more

We studied the functional organization of human posterior parietal and frontal cortex using functional magnetic resonance imaging (fMRI) to map preparatory signals for attending, looking, and pointing to a peripheral visual location. The human frontal eye field and two separate regions in the intraparietal sulcus were similarly recruited in all conditions, suggesting an attentional role that generalizes across response effectors. However, the preparation of a pointing movement selectively activated a different group of regions, suggesting a stronger role in motor planning. These regions were lateralized to the left hemisphere, activated by preparation of movements of either hand, and included the inferior and superior parietal lobule, precuneus, and posterior superior temporal sulcus, plus the dorsal premotor and anterior cingulate cortex anteriorly. Surface-based registration of macaque cortical areas onto the map of fMRI responses suggests a relatively good spatial correspondence ...

Change-blindness, occurs when large changes are missed under natural viewing conditions because they occur simultaneously with a brief visual disruption, perhaps caused by an eye movement,, a flicker, a blink, or a camera cut in a film... more

Change-blindness, occurs when large changes are missed under natural viewing conditions because they occur simultaneously with a brief visual disruption, perhaps caused by an eye movement,, a flicker, a blink, or a camera cut in a film sequence. We have found that this can occur even when the disruption does not cover or obscure the changes. When a few small, high-contrast shapes are briefly spattered over a picture, like mudsplashes on a car windscreen, large changes can be made simultaneously in the scene without being noticed. This phenomenon is potentially important in driving, surveillance or navigation, as dangerous events occurring in full view can go unnoticed if they coincide with even very small, apparently innocuous, disturbances. It is also important for understanding how the brain represents the world.

In a task requiring an optimal hand pointing (with regards to both time and accuracy) at a peripheral target, there is first a saccade of the eye within 250 ms, followed 100 ms later by the hand movement. However the latency of the hand... more

In a task requiring an optimal hand pointing (with regards to both time and accuracy) at a peripheral target, there is first a saccade of the eye within 250 ms, followed 100 ms later by the hand movement. However the latency of the hand movement is poorly correlated with that of the eye movement. When the peripheral target is cut off at the onset of the saccade, there is no correlation between the error of the gaze position and the error of the hand pointing. This suggests an early parallel processing of the two motor outputs. The duration of hand movement does not change significantly when subjects either see or not see their hand (closed or open loop). In the open loop situation, the undershoot of the hand pointing increases with target eccentricity, whatever the subjects are allowed or not to do a saccade toward the target. It suggests that the encoding of eye position by itself is a poor index for an accurately guided movement of the hand.

The spatial and temporal organization of hand and eye movements were studied in normal human subjects as they pointed toward small visual targets. The experiment was designed to assess the role of information about target position in... more

The spatial and temporal organization of hand and eye movements were studied in normal human subjects as they pointed toward small visual targets. The experiment was designed to assess the role of information about target position in correcting the trajectory of the hand when view of the hand was not available. To accomplish this, the duration of target presentation was systematically varied across blocks of trials. The results of this experiment showed that pointing movements were about 3 times more accurate when the target was present throughout the entire pointing movement, than when the target disappeared shortly after the hand movement had begun. These data indicate that pointing movements made without view of the limb are not purely preprogrammed but instead, are corrected during their execution. These modifications to the motor program are smoothly integrated into the ongoing movement and must depend upon comparing visual information about the position of the target with non-visual information about the position of the limb. The source of this non-visual information was not directly established in the present experiment but presumably must be derived from kinesthetic reafferences and/or efference copy.