@article{ThielRomanoKurthsetal.2008, author = {Thiel, Marco and Romano, Maria Carmen and Kurths, J{\"u}rgen and Rolfs, Martin and Kliegl, Reinhold}, title = {Generating surrogates from recurrences}, issn = {1364-503X}, year = {2008}, abstract = {In this paper, we present an approach to recover the dynamics from recurrences of a system and then generate (multivariate) twin surrogate (TS) trajectories. In contrast to other approaches, such as the linear-like surrogates, this technique produces surrogates which correspond to an independent copy of the underlying system, i.e. they induce a trajectory of the underlying system visiting the attractor in a different way. We show that these surrogates are well suited to test for complex synchronization, which makes it possible to systematically assess the reliability of synchronization analyses. We then apply the TS to study binocular fixational movements and find strong indications that the fixational movements of the left and right eye are phase synchronized. This result indicates that there might be only one centre in the brain that produces the fixational movements in both eyes or a close link between the two centres.}, language = {en} } @article{RolfsEngbertKliegl2005, author = {Rolfs, Martin and Engbert, Ralf and Kliegl, Reinhold}, title = {Crossmodal coupling of oculomotor control and spatial attention in vision and audition}, issn = {0014-4819}, year = {2005}, abstract = {Fixational eye movements occur involuntarily during visual fixation of stationary scenes. The fastest components of these miniature eye movements are microsaccades, which can be observed about once per second. Recent studies demonstrated that microsaccades are linked to covert shifts of visual attention. Here, we generalized this finding in two ways. First, we used peripheral cues, rather than the centrally presented cues of earlier studies. Second, we spatially cued attention in vision and audition to visual and auditory targets. An analysis of microsaccade responses revealed an equivalent impact of visual and auditory cues on microsaccade-rate signature (i.e. an initial inhibition followed by an overshoot and a final return to the pre-cue baseline rate). With visual cues or visual targets, microsaccades were briefly aligned with cue direction and then opposite to cue direction during the overshoot epoch, probably as a result of an inhibition of an automatic saccade to the peripheral cue. With left auditory cues and auditory targets microsaccades oriented in cue direction. We argue that microsaccades can be used to study crossmodal integration of sensory information and to map the time course of saccade preparation during covert shifts of visual and auditory attention}, language = {en} } @article{KlieglGrabnerRolfsetal.2004, author = {Kliegl, Reinhold and Grabner, Ellen and Rolfs, Martin and Engbert, Ralf}, title = {Length, frequency, and predictability effects of words on eye movements in reading}, year = {2004}, language = {en} } @phdthesis{Rolfs2007, author = {Rolfs, Martin}, title = {In-between fixation and movement : on the generation of microsaccades and what they convey about saccade generation}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-14581}, school = {Universit{\"a}t Potsdam}, year = {2007}, abstract = {Microsaccades are an important component of the small eye movements that constitute fixation, the basis of visual perception. The specific function of microsaccades has been a long-standing research problem. Only recently, conclusive evidence emerged, showing that microsaccades aid both visual perception and oculomotor control. The main goal of this thesis was to improve our understanding of the implementation of microsaccade generation within the circuitry of saccade control, an unsolved issue in oculomotor research. We make a case for a model according to which microsaccades and saccades result from mutually dependent motor plans, competing for expression. The model consists of an activation field, coding for fixation at its center and for saccades at peripheral locations; saccade amplitude increases with eccentricity. Activity during fixation spreads to slightly peripheral locations in the field and, thus, may result in the generation of microsaccades. Inhibition of remote and excitation of neighbouring locations govern the dynamics of the field, resulting in a strong competition between fixation and saccade generation. We propose that this common-field model of microsaccade and saccade generation finds a neurophysiological counterpart in the motor map of the superior colliculus (SC), a key brainstem structure involved in the generation of saccades. In a series of five behavioral experiments, we tested implications of the model. Predictions were derived concerning (1) the behavior of microsaccades in a given task (microsaccade rate, amplitude, and direction), (2) the interactions of microsaccades and subsequent saccades, and (3) the relationship between microsaccadic behavior and neurophysiological processes at the level of the SC. The results yielded strong support for the model at all three levels of analysis, suggesting that microsaccade statistics are indicative of the state of the fixation-related part of the SC motor map.}, language = {en} } @misc{DambacherRolfsGoellneretal.2009, author = {Dambacher, Michael and Rolfs, Martin and G{\"o}llner, Kristin and Kliegl, Reinhold and Jacobs, Arthur M.}, title = {Event-related potentials reveal rapid verification of predicted visual input}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-44953}, year = {2009}, abstract = {Human information processing depends critically on continuous predictions about upcoming events, but the temporal convergence of expectancy-based top-down and input-driven bottom-up streams is poorly understood. We show that, during reading, event-related potentials differ between exposure to highly predictable and unpredictable words no later than 90 ms after visual input. This result suggests an extremely rapid comparison of expected and incoming visual information and gives an upper temporal bound for theories of top-down and bottom-up interactions in object recognition.}, language = {en} } @article{ThielRomanoKurthsetal.2006, author = {Thiel, Marco and Romano, Maria Carmen and Kurths, J{\"u}rgen and Rolfs, Martin and Kliegl, Reinhold}, title = {Twin surrogates to test for complex synchronisation}, doi = {10.1209/epl/i2006-10147-0}, year = {2006}, abstract = {We present an approach to generate (multivariate) twin surrogates (TS) based on recurrence properties. This technique generates surrogates which correspond to an independent copy of the underlying system, i.e. they induce a trajectory of the underlying system starting at different initial conditions. We show that these surrogates are well suited to test for complex synchronisation and exemplify this for the paradigmatic system of Rossler oscillators. The proposed test enables to assess the statistical relevance of a synchronisation analysis from passive experiments which are typical in natural systems}, language = {en} } @article{RolfsDambacherCavanagh2013, author = {Rolfs, Martin and Dambacher, Michael and Cavanagh, Patrick}, title = {Visual adaptation of the perception of causality}, series = {Current biology}, volume = {23}, journal = {Current biology}, number = {3}, publisher = {Cell Press}, address = {Cambridge}, issn = {0960-9822}, doi = {10.1016/j.cub.2012.12.017}, pages = {250 -- 254}, year = {2013}, abstract = {We easily recover the causal properties of visual events, enabling us to understand and predict changes in the physical world. We see a tennis racket hitting a ball and sense that it caused the ball to fly over the net; we may also have an eerie but equally compelling experience of causality if the streetlights turn on just as we slam our car's door. Both perceptual [1] and cognitive [2] processes have been proposed to explain these spontaneous inferences, but without decisive evidence one way or the other, the question remains wide open [3-8]. Here, we address this long-standing debate using visual adaptation-a powerful tool to uncover neural populations that specialize in the analysis of specific visual features [9-12]. After prolonged viewing of causal collision events called "launches" [1], subsequently viewed events were judged more often as noncausal. These negative aftereffects of exposure to collisions are spatially localized in retinotopic coordinates, the reference frame shared by the retina and visual cortex. They are not explained by adaptation to other stimulus features and reveal visual routines in retinotopic cortex that detect and adapt to cause and effect in simple collision stimuli.}, language = {en} } @article{LaubrockKlieglRolfsetal.2010, author = {Laubrock, Jochen and Kliegl, Reinhold and Rolfs, Martin and Engbert, Ralf}, title = {When do microsaccades follow spatial attention?}, issn = {1943-3921}, doi = {10.3758/APP.72.3.683}, year = {2010}, abstract = {Following up on an exchange about the relation between microsaccades and spatial attention (Horowitz, Fencsik, Fine, Yurgenson, \& Wolfe, 2007; Horowitz, Fine, Fencsik, Yurgenson, \& Wolfe, 2007; Laubrock, Engbert, Rolfs, \& Kliegl, 2007), we examine the effects of selection criteria and response modality. We show that for Posner cuing with saccadic responses, microsaccades go with attention in at least 75\% of cases (almost 90\% if probability matching is assumed) when they are first (or only) microsaccades in the cue target interval and when they occur between 200 and 400 msec after the cue. The relation between spatial attention and the direction of microsaccades drops to chance level for unselected microsaccades collected during manual-response conditions. Analyses of data from four cross-modal cuing experiments demonstrate an above-chance, intermediate link for visual cues, but no systematic relation for auditory cues. Thus, the link between spatial attention and direction of microsaccades depends on the experimental condition and time of occurrence, but it can be very strong.}, language = {en} } @article{RolfsLaubrockKliegl2006, author = {Rolfs, Martin and Laubrock, Jochen and Kliegl, Reinhold}, title = {Shortening and prolongation of saccade latencies following microsaccades}, doi = {10.1007/s00221-005-0148-1}, year = {2006}, abstract = {When the eyes fixate at a point in a visual scene, small saccades rapidly shift the image on the retina. The effect of these microsaccades on the latency of subsequent large-scale saccades may be twofold. First, microsaccades are associated with an enhancement of visual perception. Their occurrence during saccade target perception could, thus, decrease saccade latencies. Second, microsaccades are likely to indicate activity in fixation-related oculomotor neurons. These represent competitors to saccade-related cells in the interplay of gaze holding and shifting. Consequently, an increase in saccade latencies would be expected after microsaccades. Here, we present evidence for both aspects of microsaccadic impact on saccade latency. In a delayed response task, participants made saccades to visible or memorized targets. First, microsaccade occurrence up to 50 ms before target disappearance correlated with 18 ms (or 8\%) faster saccades to memorized targets. Second, if microsaccades occurred shortly (i.e., < 150 ms) before a saccade was required, mean saccadic reaction time in visual and memory trials was increased by about 40 ms (or 16\%). Hence, microsaccades can have opposite consequences for saccade latencies, pointing at a differential role of these fixational eye movements in the preparation of saccade motor programs}, language = {en} } @article{KinderRolfsKliegl2008, author = {Kinder, Annette and Rolfs, Martin and Kliegl, Reinhold}, title = {Sequence learning at optimal stimulus-response mapping : evidence from a serial reaction-time task}, doi = {10.1080/17470210701557555}, year = {2008}, abstract = {We propose a new version of the serial reaction time (SRT) task in which participants merely looked at the target instead of responding manually. As response locations were identical to target locations, stimulus - response compatibility was maximal in this task. We demonstrated that saccadic response times decreased during training and increased again when a new sequence was presented. It is unlikely that this effect was caused by stimulus - response (S - R) learning because bonds between (visual) stimuli and (oculomotor) responses were already well established before the experiment started. Thus, the finding shows that the building of S - R bonds is not essential for learning in the SRT task.}, language = {en} } @article{BoettcherRolfsKliegletal.2009, author = {B{\"o}ttcher, Heiko and Rolfs, Martin and Kliegl, Reinhold and Ihle, Wolfgang}, title = {Inattentional blindness and change blindness bei Jungen mit ADHS}, year = {2009}, language = {en} } @article{BoettcherRolfsKliegletal.2009, author = {B{\"o}ttcher, Heiko and Rolfs, Martin and Kliegl, Reinhold and Ihle, Wolfgang}, title = {Inattentional blindness and change blindness bei Jungen mit ADHS : Posterpr{\"a}sentation}, issn = {1616-3443}, doi = {10.1026/1616-3443.38.S1.20}, year = {2009}, language = {de} } @article{KlieglRolfsLaubrocketal.2009, author = {Kliegl, Reinhold and Rolfs, Martin and Laubrock, Jochen and Engbert, Ralf}, title = {Microsaccadic modulation of response times in spatial attention tasks}, issn = {0340-0727}, doi = {10.1007/s00426-008-0202-2}, year = {2009}, language = {en} } @article{RolfsLaubrockKliegl2008, author = {Rolfs, Martin and Laubrock, Jochen and Kliegl, Reinhold}, title = {Microsaccade-induced prolongation of saccadic latencies depends on microsaccade amplitude}, issn = {1995-8692}, year = {2008}, language = {en} } @article{Rolfs2009, author = {Rolfs, Martin}, title = {Microsaccades : small steps on a long way}, issn = {0042-6989}, doi = {10.1016/j.visres.2009.08.010}, year = {2009}, abstract = {Contrary to common wisdom, fixations are a dynamically rich behavior, composed of continual, miniature eye movements, of which microsaccades are the most salient component. Over the last few years, interest in these small movements has risen dramatically, driven by both neurophysiological and psychophysical results and by advances in techniques, analysis, and modeling of eye movements. The field has a long history but a significant portion of the earlier work has gone missing in the current literature, in part, as a result of the collapse of the field in the 1980s that followed a series of discouraging results. The present review compiles 60 years of work demonstrating the unique contribution of microsaccades to visual and oculomotor function. Specifically, the review covers the contribution of microsaccades to (1) the control of fixation position, (2) the reduction of perceptual fading and the continuity of perception, (3) the generation of synchronized visual transients, (4) visual acuity, (5) scanning of small spatial regions, (6) shifts of spatial attention, (7) resolving perceptual ambiguities in the face of multistable perception, as well as several other functions. The accumulated evidence demonstrates that microsaccades serve both perceptual and oculomotor goals and although in some cases their contribution is neither necessary nor unique, microsaccades are a malleable tool conveniently employed by the visual system.}, language = {en} } @article{LaubrockEngbertRolfsetal.2007, author = {Laubrock, Jochen and Engbert, Ralf and Rolfs, Martin and Kliegl, Reinhold}, title = {Microsaccades are an index of covert attention : commentary on Horowitz, Fine, Fencsik, Yurgenson and Wolfe}, issn = {0956-7976}, doi = {10.1111/j.1467-9280.2007.01904.x}, year = {2007}, language = {en} } @article{RolfsOhl2011, author = {Rolfs, Martin and Ohl, Sven}, title = {Visual suppression in the superior colliculus around the time of microsaccades}, series = {Journal of neurophysiology}, volume = {105}, journal = {Journal of neurophysiology}, number = {1}, publisher = {American Chemical Society}, address = {Bethesda}, issn = {0022-3077}, doi = {10.1152/jn.00862.2010}, pages = {1 -- 3}, year = {2011}, abstract = {Miniature eye movements jitter the retinal image unceasingly, raising the question of how perceptual continuity is achieved during visual fixation. Recent work discovered suppression of visual bursts in the superior colliculus around the time of microsaccades, tiny jerks of the eyes that support visual perception while gaze is fixed. This finding suggests that corollary discharge, supporting visual stability when rapid eye movements drastically shift the retinal image, may also exist for the smallest saccades.}, language = {en} } @misc{KlieglRolfsLaubrocketal.2009, author = {Kliegl, Reinhold and Rolfs, Martin and Laubrock, Jochen and Engbert, Ralf}, title = {Microsaccadic Modulation of Response Times in Spatial Attention Tasks}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-57098}, year = {2009}, abstract = {Covert shifts of attention are usually reflected in RT differences between responses to valid and invalid cues in the Posner spatial attention task. Such inferences about covert shifts of attention do not control for microsaccades in the cue target interval. We analyzed the effects of microsaccade orientation on RTs in four conditions, crossing peripheral visual and auditory cues with peripheral visual and auditory discrimination targets. Reaction time was generally faster on trials without microsaccades in the cue-target interval. If microsaccades occurred, the target-location congruency of the last microsaccade in the cuetarget interval interacted in a complex way with cue validity. For valid visual cues, irrespective of whether the discrimination target was visual or auditory, target-congruent microsaccades delayed RT. For invalid cues, target-incongruent microsaccades facilitated RTs for visual target discrimination, but delayed RT for auditory target discrimination. No reliable effects on RT were associated with auditory cues or with the first microsaccade in the cue-target interval. We discuss theoretical implications on the relation about spatial attention and oculomotor processes.}, language = {en} } @article{RolfsKlieglEngbert2008, author = {Rolfs, Martin and Kliegl, Reinhold and Engbert, Ralf}, title = {Toward a model of microsaccade generation : the case of microsaccadic inhibition}, issn = {1534-7362}, doi = {10.1167/8.11.5}, year = {2008}, language = {en} } @misc{RolfsEngbertKliegl2005, author = {Rolfs, Martin and Engbert, Ralf and Kliegl, Reinhold}, title = {Crossmodal coupling of oculomotor controland spatial attention in vision and audition}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-56804}, year = {2005}, abstract = {Fixational eye movements occur involuntarily during visual fixation of stationary scenes. The fastest components of these miniature eye movements are microsaccades, which can be observed about once per second. Recent studies demonstrated that microsaccades are linked to covert shifts of visual attention [e.g., Engbert \& Kliegl (2003), Vision Res 43:1035-1045]. Here,we generalized this finding in two ways. First, we used peripheral cues, rather than the centrally presented cues of earlier studies. Second, we spatially cued attention in vision and audition to visual and auditory targets. An analysis of microsaccade responses revealed an equivalent impact of visual and auditory cues on microsaccade-rate signature (i.e., an initial inhibition followed by an overshoot and a final return to the pre-cue baseline rate). With visual cues or visual targets,microsaccades were briefly aligned with cue direction and then opposite to cue direction during the overshoot epoch, probably as a result of an inhibition of an automatic saccade to the peripheral cue. With left auditory cues and auditory targets microsaccades oriented in cue direction. Thus, microsaccades can be used to study crossmodal integration of sensory information and to map the time course of saccade preparation during covert shifts of visual and auditory attention.}, language = {en} } @misc{RolfsKlieglEngbert2004, author = {Rolfs, Martin and Kliegl, Reinhold and Engbert, Ralf}, title = {Microsaccade orientation supports attentional enhancement opposite to a peripheral cue: Commentary on Tse, Sheinberg, and Logothetis}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-57081}, year = {2004}, language = {en} } @article{RolfsEngbertKliegl2004, author = {Rolfs, Martin and Engbert, Ralf and Kliegl, Reinhold}, title = {Microsaccade orientation supports attentional enhancement opposite to a peripheral cue}, year = {2004}, language = {en} } @article{RomanoThielKurthsetal.2006, author = {Romano, Maria Carmen and Thiel, Marco and Kurths, J{\"u}rgen and Rolfs, Martin and Engbert, Ralf and Kliegl, Reinhold}, title = {Synchronization Analysis and Recurrence in Complex Systems}, isbn = {978-3-527-40623-4}, year = {2006}, language = {en} } @misc{ThielRomanoKurthsetal.2006, author = {Thiel, Marco and Romano, Maria Carmen and Kurths, J{\"u}rgen and Rolfs, Martin and Kliegl, Reinhold}, title = {Generating Surrogates from Recurrences}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-56906}, year = {2006}, abstract = {In this paper we present an approach to recover the dynamics from recurrences of a system and then generate (multivariate) twin surrogate (TS) trajectories. In contrast to other approaches, such as the linear-like surrogates, this technique produces surrogates which correspond to an independent copy of the underlying system, i. e. they induce a trajectory of the underlying system visiting the attractor in a different way. We show that these surrogates are well suited to test for complex synchronization, which makes it possible to systematically assess the reliability of synchronization analyses. We then apply the TS to study binocular fixational movements and find strong indications that the fixational movements of the left and right eye are phase synchronized. This result indicates that there might be one centre only in the brain that produces the fixational movements in both eyes or a close link between two centres.}, language = {en} } @misc{RolfsLaubrockKliegl2006, author = {Rolfs, Martin and Laubrock, Jochen and Kliegl, Reinhold}, title = {Shortening and Prolongation of Saccade Latencies Following Microsaccades}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-57012}, year = {2006}, abstract = {When the eyes fixate at a point in a visual scene, small saccades rapidly shift the image on the retina. The effect of these microsaccades on the latency of subsequent large-scale saccades may be twofold. First, microsaccades are associated with an enhancement of visual perception. Their occurrence during saccade target perception should, thus, decrease saccade latencies. On the other hand, microsaccades likely indicate activity in fixation-related oculomotor neurons. These represent competitors to saccade-related cells in the interplay of gaze holding and shifting. Consequently, an increase in saccade latencies after microsaccades would be expected. Here, we present evidence for both aspects of microsaccadic impact on saccade latency. In a delayed response task, participants made saccades to visible or memorized targets. First, microsaccade occurrence up to 50 ms before target disappearance correlated with 18 ms (or 8\%) faster saccades to memorized targets. Second, if microsaccades occurred shortly (i.e., < 150 ms) before a saccade was required, saccadic reaction times in visual and memory trials were increased by about 40 ms (or 16\%). Hence, microsaccades can have opposite consequences for saccade latencies, pointing at a differential role of these fixational eye movements in preparation of motor programs.}, language = {en} } @misc{ThielRomanoKurthsetal.2006, author = {Thiel, Marco and Romano, Maria Carmen and Kurths, J{\"u}rgen and Rolfs, Martin}, title = {Twin Surrogates to Test for Complex Synchronisation}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-57231}, year = {2006}, abstract = {We present an approach to generate (multivariate) twin surrogates (TS) based on recurrence properties. This technique generates surrogates which correspond to an independent copy of the underlying system, i. e. they induce a trajectory of the underlying system starting at different initial conditions. We show that these surrogates are well suited to test for complex synchronisation and exemplify this for the paradigmatic system of R¨ossler oscillators. The proposed test enables to assess the statistical relevance of a synchronisation analysis from passive experiments which are typical in natural systems.}, language = {en} }