Is Direction Position? Position- and Direction-Based Correspondence Effects in Tasks with Moving Stimuli

Five experiments were carried out to test whether (task-irrelevant) motion information provided by a stimulus changing its position over time would affect manual left–right responses. So far, some studies reported direction-based Simon effects whereas others did not. In Experiment 1a, a reliable direction-based effect occurred, which was not modulated by the response mode—that is, by whether participants responded by pressing one of two keys or more dynamically by moving a stylus in a certain direction. Experiments 1a, 1b, and 2 lend support to the idea that observers use the starting position of target motion as a reference for spatial coding. That is, observers might process object motion as a shift of position relative to the starting position and not as directional information. The dominance of relative position coding could also be shown in Experiment 3, in which relative position was pitted against motion direction by presenting a static and dynamic stimulus at the same time. Additionally, we explored the role of eye movements in stimulus–response compatibility and showed in Experiments 1b and 3a that the execution or preparation of saccadic eye movements—as proposed by an attention-shifting account—is not necessary for a Simon effect to occur.

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Distributed spatial coding in the superior colliculus: A review

Visual Neuroscience ◽

10.1017/s0952523800000857 ◽

1991 ◽

Vol 6 (1) ◽

pp. 3-13 ◽

Cited By ~ 60

Author(s):

James T. McIlwain

Keyword(s):

Eye Movements ◽

Superior Colliculus ◽

Receptive Fields ◽

Saccadic Eye Movements ◽

Visual Direction ◽

Saccade Amplitude ◽

Spatial Coding ◽

Distributed Coding

AbstractThis paper reviews evidence that the superior colliculus (SC) of the midbrain represents visual direction and certain aspects of saccadic eye movements in the distribution of activity across a population of cells. Accurate and precise eye movements appear to be mediated, in part at least, by cells of the SC that have large sensory receptive fields and/or discharge in association with a range of saccades. This implies that visual points or saccade targets are represented by patches rather than points of activity in the SC. Perturbation of the pattern of collicular discharge by focal inactivation modifies saccade amplitude and direction in a way consistent with distributed coding. Several models have been advanced to explain how such a code might be implemented in the colliculus. Evidence related to these hypotheses is examined and continuing uncertainties are identified.

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Predicting 2D Target Velocity Cannot Help 2D Motion Integration for Smooth Pursuit Initiation

Journal of Neurophysiology ◽

10.1152/jn.00563.2006 ◽

2006 ◽

Vol 96 (6) ◽

pp. 3545-3550 ◽

Cited By ~ 12

Author(s):

Anna Montagnini ◽

Miriam Spering ◽

Guillaume S. Masson

Keyword(s):

Eye Movements ◽

Smooth Pursuit ◽

Object Motion ◽

Line Orientation ◽

Motion Direction ◽

Direction Error ◽

Pursuit Eye Movements ◽

Pursuit Initiation ◽

Motion Integration ◽

Tracking Direction

Smooth pursuit eye movements reflect the temporal dynamics of bidimensional (2D) visual motion integration. When tracking a single, tilted line, initial pursuit direction is biased toward unidimensional (1D) edge motion signals, which are orthogonal to the line orientation. Over 200 ms, tracking direction is slowly corrected to finally match the 2D object motion during steady-state pursuit. We now show that repetition of line orientation and/or motion direction does not eliminate the transient tracking direction error nor change the time course of pursuit correction. Nonetheless, multiple successive presentations of a single orientation/direction condition elicit robust anticipatory pursuit eye movements that always go in the 2D object motion direction not the 1D edge motion direction. These results demonstrate that predictive signals about target motion cannot be used for an efficient integration of ambiguous velocity signals at pursuit initiation.

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Influence of visual perception on spatial coding of saccadic eye movements and fixation

Neuro-Ophthalmology ◽

10.1080/01658100490887931 ◽

2004 ◽

Vol 28 (5-6) ◽

pp. 197-204 ◽

Cited By ~ 3

Author(s):

Helmut Tegetmeyer ◽

Anja Wenger

Keyword(s):

Eye Movements ◽

Visual Perception ◽

Saccadic Eye Movements ◽

Spatial Coding

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Object Motion Computation for the Initiation of Smooth Pursuit Eye Movements in Humans

Journal of Neurophysiology ◽

10.1152/jn.01042.2004 ◽

2005 ◽

Vol 93 (4) ◽

pp. 2279-2293 ◽

Cited By ~ 28

Author(s):

Julian M. Wallace ◽

Leland S. Stone ◽

Guillaume S. Masson

Keyword(s):

Eye Movements ◽

Smooth Pursuit ◽

Object Motion ◽

Type I ◽

Type Ii ◽

Smooth Pursuit Eye Movements ◽

Motion Direction ◽

Pursuit Eye Movements ◽

Motion Computation ◽

Tracking Direction

Pursuing an object with smooth eye movements requires an accurate estimate of its two-dimensional (2D) trajectory. This 2D motion computation requires that different local motion measurements are extracted and combined to recover the global object-motion direction and speed. Several combination rules have been proposed such as vector averaging (VA), intersection of constraints (IOC), or 2D feature tracking (2DFT). To examine this computation, we investigated the time course of smooth pursuit eye movements driven by simple objects of different shapes. For type II diamond (where the direction of true object motion is dramatically different from the vector average of the 1-dimensional edge motions, i.e., VA ≠ IOC = 2DFT), the ocular tracking is initiated in the vector average direction. Over a period of less than 300 ms, the eye-tracking direction converges on the true object motion. The reduction of the tracking error starts before the closing of the oculomotor loop. For type I diamonds (where the direction of true object motion is identical to the vector average direction, i.e., VA = IOC = 2DFT), there is no such bias. We quantified this effect by calculating the direction error between responses to types I and II and measuring its maximum value and time constant. At low contrast and high speeds, the initial bias in tracking direction is larger and takes longer to converge onto the actual object-motion direction. This effect is attenuated with the introduction of more 2D information to the extent that it was totally obliterated with a texture-filled type II diamond. These results suggest a flexible 2D computation for motion integration, which combines all available one-dimensional (edge) and 2D (feature) motion information to refine the estimate of object-motion direction over time.

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Blink-Perturbed Saccades in Monkey. I. Behavioral Analysis

Journal of Neurophysiology ◽

10.1152/jn.2000.83.6.3411 ◽

2000 ◽

Vol 83 (6) ◽

pp. 3411-3429 ◽

Cited By ~ 51

Author(s):

H.H.L.M. Goossens ◽

A. J. Van Opstal

Keyword(s):

Eye Movements ◽

Saccadic Eye Movements ◽

Neural Mechanism ◽

Linear Superposition ◽

Velocity Amplitude ◽

Starting Position ◽

Restoring Forces ◽

Reflex Blinks ◽

Saccade Trajectory ◽

Straight Ahead

Saccadic eye movements are thought to be influenced by blinking through premotor interactions, but it is still unclear how. The present paper describes the properties of blink-associated eye movements and quantifies the effect of reflex blinks on the latencies, metrics, and kinematics of saccades in the monkey. In particular, it is examined to what extent the saccadic system accounts for blink-related perturbations of the saccade trajectory. Trigeminal reflex blinks were elicited near the onset of visually evoked saccades by means of air puffs directed on the eye. Reflex blinks were also evoked during a straight-ahead fixation task. Eye and eyelid movements were measured with the magnetic-induction technique. The data show that saccade latencies were reduced substantially when reflex blinks were evoked prior to the impending visual saccades as if these saccades were triggered by the blink. The evoked blinks also caused profound spatial-temporal perturbations of the saccades. Deflections of the saccade trajectory, usually upward, extended up to ∼15°. Saccade peak velocities were reduced, and a two- to threefold increase in saccade duration was typically observed. In general, these perturbations were largely compensated in saccade mid-flight, despite the absence of visual feedback, yielding near-normal endpoint accuracies. Further analysis revealed that blink-perturbed saccades could not be described as a linear superposition of a pure blink-associated eye movement and an unperturbed saccade. When evoked during straight-ahead fixation, blinks were accompanied by initially upward and slightly abducting eye rotations of ∼2–15°. Back and forth wiggles of the eye were frequently seen; but in many cases the return movement was incomplete. Rather than drifting back to its starting position, the eye then maintained its eccentric orbital position until a downward corrective saccade toward the fixation spot followed. Blink-associated eye movements were quite rapid, albeit slower than saccades, and the velocity-amplitude-duration characteristics of the initial excursions as well as the return movements were approximately linear. These data strongly support the idea that blinks interfere with the saccade premotor circuit, presumably upstream from the neural eye-position integrator. They also indicated that a neural mechanism, rather than passive elastic restoring forces within the oculomotor plant, underlies the compensatory behavior. The tight latency coupling between saccades and blinks is consistent with an inhibition of omnipause neurons by the blink system, suggesting that the observed changes in saccade kinematics arise elsewhere in the saccadic premotor system.

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