ORCID Profile
0000-0002-8214-8556
Current Organisation
Humboldt-Universität zu Berlin
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Publisher: Elsevier BV
Date: 06-2013
Publisher: Cold Spring Harbor Laboratory
Date: 19-07-2023
DOI: 10.1101/2023.07.17.549281
Abstract: Perception relies on active s ling of the environment. What part of the physical world can be sensed is limited by biophysical constraints of sensory systems, but might be further constrained by the kinematic bounds of the motor actions that acquire sensory information. We tested this fundamental idea for humans’ fastest and most frequent behavior—saccadic eye movements—which entails retinal motion that commonly escapes visual awareness. We discover that the visibility of a high-speed stimulus, presented during fixation, is predicted by the lawful sensorimotor contingencies that saccades routinely impose on the retina, reflecting even distinctive variability between observers’ movements. Our results suggest that the visual systems’ functional and implementational properties are best understood in the context of movement kinematics that impact its sensory surface.
Publisher: Association for Research in Vision and Ophthalmology (ARVO)
Date: 16-10-2015
DOI: 10.1167/15.14.7
Publisher: Elsevier BV
Date: 09-2018
DOI: 10.1016/J.CONCOG.2018.05.004
Abstract: Saccades rapidly jerk the eye into new positions, yet we rarely experience the motion streaks imposed on the retinal image. Here we examined spatial and temporal properties of post-saccadic masking-one potential explanation of this perceptual omission. Observers judged the motion direction of a target stimulus, a Gaussian blob, that moved vertically upwards or downwards and then back to its initial position, just as observers made a saccade. We manipulated the onset and offset of the target and of distractors in various spatial relations to the target, and assessed their effect on performance and subjective confidence. Although the presence of the target after the saccade caused the strongest omission, the offset of spatially distant distractor stimuli upon saccade offset also impaired performance. The temporal properties of these two separate effects suggest that, in addition to masking, an independent effect of attentional distraction further accentuates perceptual omission of intra-saccadic motion streaks.
Publisher: SAGE Publications
Date: 03-08-2019
Abstract: As the eyes move, they incessantly impose motion blur on the retinal image, yet our perception of the world remains undisturbed. In fact, it is often assumed that intrasaccadic visual signals are largely eliminated from processing by a dedicated suppression mechanism. Here, we describe an easy-to-build presentation device that produces a stimulus that is highly salient and well resolvable during saccades: Using LED strips with high temporal resolution, any type of text and image stimulus can be presented in an anorthoscopic fashion—as if seen through and travelling behind a narrow slit—at very short durations. Whereas these stimuli appear as a brief flash during fixation, saccades spread them across the retina, producing spatially extended and well-resolved retinal images. In fact, retinally painted images induced by saccades across a series of anorthoscopic image presentations were correctly identified by observers in 90% of all cases. So why should we suppress intrasaccadic perception if it enables us to experience the joy of retinal painting?
Publisher: Society for Neuroscience
Date: 13-08-2018
DOI: 10.1523/JNEUROSCI.0736-18.2018
Abstract: Transmission delays in the nervous system pose challenges for the accurate localization of moving objects as the brain must rely on outdated information to determine their position in space. Acting effectively in the present requires that the brain compensates not only for the time lost in the transmission and processing of sensory information, but also for the expected time that will be spent preparing and executing motor programs. Failure to account for these delays will result in the mislocalization and mistargeting of moving objects. In the visuomotor system, where sensory and motor processes are tightly coupled, this predicts that the perceived position of an object should be related to the latency of saccadic eye movements aimed at it. Here we use the flash-grab effect, a mislocalization of briefly flashed stimuli in the direction of a reversing moving background, to induce shifts of perceived visual position in human observers (male and female). We find a linear relationship between saccade latency and perceived position shift, challenging the classic dissociation between “vision for action” and “vision for perception” for tasks of this kind and showing that oculomotor position representations are either shared with or tightly coupled to perceptual position representations. Altogether, we show that the visual system uses both the spatial and temporal characteristics of an upcoming saccade to localize visual objects for both action and perception. SIGNIFICANCE STATEMENT Accurately localizing moving objects is a computational challenge for the brain due to the inevitable delays that result from neural transmission. To solve this, the brain might implement motion extrapolation, predicting where an object ought to be at the present moment. Here, we use the flash-grab effect to induce perceptual position shifts and show that the latency of imminent saccades predicts the perceived position of the objects they target. This counterintuitive finding is important because it not only shows that motion extrapolation mechanisms indeed work to reduce the behavioral impact of neural transmission delays in the human brain, but also that these mechanisms are closely matched in the perceptual and oculomotor systems.
Publisher: American Physiological Society
Date: 02-2022
Abstract: Sometimes a visual stimulus reaches awareness, and sometimes it does not. To understand why, we need objective, bias-free measures of awareness. We discovered that a reflexive freezing of small eye movements indicates when an observer detects a stimulus. Furthermore, when we biased observers’ decisions to report seeing the stimulus, the oculomotor response was unaltered. This suggests that the threshold for conscious perception is independent of the decision criterion and is revealed by oculomotor freezing.
No related grants have been discovered for Martin Rolfs.