TY - JOUR A1 - Laubrock, Jochen A1 - Cajar, Anke A1 - Engbert, Ralf T1 - Control of fixation duration during scene viewing by interaction of foveal and peripheral processing JF - Journal of vision N2 - Processing in our visual system is functionally segregated, with the fovea specialized in processing fine detail (high spatial frequencies) for object identification, and the periphery in processing coarse information (low frequencies) for spatial orienting and saccade target selection. Here we investigate the consequences of this functional segregation for the control of fixation durations during scene viewing. Using gaze-contingent displays, we applied high-pass or low-pass filters to either the central or the peripheral visual field and compared eye-movement patterns with an unfiltered control condition. In contrast with predictions from functional segregation, fixation durations were unaffected when the critical information for vision was strongly attenuated (foveal low-pass and peripheral high-pass filtering); fixation durations increased, however, when useful information was left mostly intact by the filter (foveal high-pass and peripheral low-pass filtering). These patterns of results are difficult to explain under the assumption that fixation durations are controlled by foveal processing difficulty. As an alternative explanation, we developed the hypothesis that the interaction of foveal and peripheral processing controls fixation duration. To investigate the viability of this explanation, we implemented a computational model with two compartments, approximating spatial aspects of processing by foveal and peripheral activations that change according to a small set of dynamical rules. The model reproduced distributions of fixation durations from all experimental conditions by variation of few parameters that were affected by specific filtering conditions. KW - scene perception KW - spatial frequencies KW - fixation durations KW - computational modeling Y1 - 2013 U6 - https://doi.org/10.1167/13.12.11 SN - 1534-7362 VL - 13 IS - 12 PB - Association for Research in Vision and Opthalmology CY - Rockville ER - TY - JOUR A1 - Dambacher, Michael A1 - Slattery, Timothy J. A1 - Yang, Jinmian A1 - Kliegl, Reinhold A1 - Rayner, Keith T1 - Evidence for direct control of eye movements during reading JF - Journal of experimental psychology : Human perception and performance N2 - It is well established that fixation durations during reading vary with processing difficulty, but there are different views on how oculomotor control, visual perception, shifts of attention, and lexical (and higher cognitive) processing are coordinated. Evidence for a one-to-one translation of input delay into saccadic latency would provide a much needed constraint for current theoretical proposals. Here, we tested predictions of such a direct-control perspective using the stimulus-onset delay (SOD) paradigm. Words in sentences were initially masked and, on fixation, were individually unmasked with a delay (0-, 33-, 66-, 99-ms SODs). In Experiment 1, SODs were constant for all words in a sentence; in Experiment 2, SODs were manipulated on target words, while nontargets were unmasked without delay. In accordance with predictions of direct control, nonzero SODs entailed equivalent increases in fixation durations in both experiments. Yet, a population of short fixations pointed to rapid saccades as a consequence of low-level information at nonoptimal viewing positions rather than of lexical processing. Implications of these results for theoretical accounts of oculomotor control are discussed. KW - stimulus-onset delay KW - oculomotor control KW - fixation durations KW - sentence reading Y1 - 2013 U6 - https://doi.org/10.1037/a0031647 SN - 0096-1523 VL - 39 IS - 5 SP - 1468 EP - 1484 PB - American Psychological Association CY - Washington ER - TY - THES A1 - Trukenbrod, Hans Arne T1 - Temporal and spatial aspects of eye-movement control : from reading to scanning T1 - Zeitliche und räumliche Aspekte der Blicksteuerung : vom Lesen zum Scannen N2 - Eye movements are a powerful tool to examine cognitive processes. However, in most paradigms little is known about the dynamics present in sequences of saccades and fixations. In particular, the control of fixation durations has been widely neglected in most tasks. As a notable exception, both spatial and temporal aspects of eye-movement control have been thoroughly investigated during reading. There, the scientific discourse was dominated by three controversies, (i), the role of oculomotor vs. cognitive processing on eye-movement control, (ii) the serial vs. parallel processing of words, and, (iii), the control of fixation durations. The main purpose of this thesis was to investigate eye movements in tasks that require sequences of fixations and saccades. While reading phenomena served as a starting point, we examined eye guidance in non-reading tasks with the aim to identify general principles of eye-movement control. In addition, the investigation of eye movements in non-reading tasks helped refine our knowledge about eye-movement control during reading. Our approach included the investigation of eye movements in non-reading experiments as well as the evaluation and development of computational models. I present three main results : First, oculomotor phenomena during reading can also be observed in non-reading tasks (Chapter 2 & 4). Oculomotor processes determine the fixation position within an object. The fixation position, in turn, modulates both the next saccade target and the current fixation duration. Second, predicitions of eye-movement models based on sequential attention shifts were falsified (Chapter 3). In fact, our results suggest that distributed processing of multiple objects forms the basis of eye-movement control. Third, fixation durations are under asymmetric control (Chapter 4). While increasing processing demands immediately prolong fixation durations, decreasing processing demands reduce fixation durations only with a temporal delay. We propose a computational model ICAT to account for asymmetric control. In this model, an autonomous timer initiates saccades after random time intervals independent of ongoing processing. However, processing demands that are higher than expected inhibit the execution of the next saccade and, thereby, prolong the current fixation. On the other hand, lower processing demands will not affect the duration before the next saccade is executed. Since the autonomous timer adjusts to expected processing demands from fixation to fixation, a decrease in processing demands may lead to a temporally delayed reduction of fixation durations. In an extended version of ICAT, we evaluated its performance while simulating both temporal and spatial aspects of eye-movement control. The eye-movement phenomena investigated in this thesis have now been observed in a number of different tasks, which suggests that they represent general principles of eye guidance. I propose that distributed processing of the visual input forms the basis of eye-movement control, while fixation durations are controlled by the principles outlined in ICAT. In addition, oculomotor control contributes considerably to the variability observed in eye movements. Interpretations for the relation between eye movements and cognition strongly benefit from a precise understanding of this interplay. N2 - Blickbewegungen stellen ein wichtiges Instrument dar, um kognitive Prozesse zu untersuchen. In den meisten Paradigmen ist allerdings wenig über die Entstehung von Sakkaden und Fixationen bekannt. Insbesondere die Kontrolle der Fixationsdauern wurde häufig außer acht gelassen. Eine wesentliche Ausnahme stellt die Leseforschung dar, in der sowohl zeitlichliche als auch räumliche Aspekte der Blickbewegungssteuerung im Detail betrachtet wurden. Dabei war der wissenschaftliche Diskurs durch drei Kontroversen gekennzeichnet, die untersuchten, (i), welchen Einfluss okulomotorische bzw. kognitive Prozesse auf die Blicksteuerung haben, (ii), ob Worte seriell oder parallel verarbeitet werden und, (iii), wie Fixationsdauern kontrolliert werden. Die vorliegende Arbeit zielt im wesentlichen darauf ab, die Dynamik von Fixationssequenzen zu erforschen. Ausgehend von den Erkenntnissen beim Lesen untersuchten wir Blickbewegungen in Nichtlese-Aufgaben, mit dem Ziel allgemeine Prinzipien der Blicksteuerung zu identifizieren. Zusätzlich versuchten wir mit Hilfe dieser Aufgaben, Erkenntnisse über Prozesse beim Lesen zu vertiefen. Unser Vorgehen war sowohl von der Durchführung von Experimenten als auch der Entwicklung und Evaluation computationaler Modelle geprägt. Die Hauptbefunde zeigten: Erstens, okulomotorische Phänomene des Lesens lassen sich in Suchaufgaben ohne Wortmaterial replizieren (Kapitel 2 & 4). Dabei bestimmen okulomotorische Prozesse die Fixationsposition innerhalb eines Objektes. Diese wiederum beeinflusst das nächste Sakkadenziel sowie die Fixationsdauer. Zweitens, wesentliche Vorhersagen von Modellen, in denen Blickbewegungen von seriellen Aufmerksamkeitsverschiebungen abhängen, konnten falsifiziert werden (Kapitel 3). Stattdessen legen unsere Erkenntnisse nahe, dass die Blicksteuerung von der parallelen Verarbeitung mehrerer Objekte abhängt. Drittens, Fixationsdauern werden asymmetrisch kontrolliert (Kapitel 4). Während hohe Verarbeitungsanforderungen Fixationsdauern unmittelbar verlängern können, führen niedrige Verarbeitungsanforderungen nur zeitlich verzögert zu einer Reduktion. Wir schlagen ein computationales Modell ICAT vor, um asymmetrische Kontrolle zu erklären. Grundlage des Modells ist ein autonomer Zeitgeber, der unabhängig von der momentanen Verarbeitung nach zufälligen Zeitintervallen Sakkaden initiiert. Unerwartet hohe Verarbeitungsanforderungen können die Initiierung der nächsten Sakkade hinauszögern, während unerwartet niedrige Verarbeitungsanforderungen den Beginn der nächsten Sakkade nicht verändern. Der Zeitgeber passt sich allerdings von Fixation zu Fixation neuen Verarbeitungsanforderungen an, so dass es zu einer zeitlich verzögerten Reduktion der Fixationsdauern kommen kann. In einer erweiterten Version des Modells überprüfen wir die Kompatibilität ICATs mit einer realistischen räumlichen Blicksteuerung. Die Ähnlichkeit von Blickbewegungsphänomenen über Aufgaben hinweg legt nahe, dass sie auf allgemeinen Prinzipien basieren. Grundlage der Blicksteuerung ist die verteilte Verarbeitung des visuellen Inputs, während die Kontrolle der Fixationsdauer auf den Prinzipien von ICAT beruht. Darüber hinaus tragen okulomotorische Phänomene wesentlich zur Variabilität der Blicksteuerung bei. Ein Verständnis dieses Zusammenspiels hilft entscheidend den Zusammenhang von Blickbewegungen und Kognitionen besser zu verstehen. KW - Blickbewegungen KW - Fixationssequenzen KW - Computationale Modellierung KW - Fixationdauern KW - Fixationspositionen KW - Eye movements KW - fixation sequences KW - computational modeling KW - fixation durations KW - fixation positions Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-70206 ER - TY - GEN A1 - Dambacher, Michael A1 - Kliegl, Reinhold T1 - Synchronizing timelines: Relations between fixation durations and N400 amplitudes during sentence reading N2 - We examined relations between eye movements (single-fixation durations) and RSVP-based event-related potentials (ERPs; N400’s) recorded during reading the same sentences in two independent experiments. Longer fixation durations correlated with larger N400 amplitudes. Word frequency and predictability of the fixated word as well as the predictability of the upcoming word accounted for this covariance in a path-analytic model. Moreover, larger N400 amplitudes entailed longer fixation durations on the next word, a relation accounted for by word frequency. This pattern offers a neurophysiological correlate for the lag-word frequency effect on fixation durations: Word processing is reliably expressed not only in fixation durations on currently fixated words, but also in those on subsequently fixated words. T3 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - paper 262 KW - sentence reading KW - eye-movements KW - fixation durations KW - rapid serial visual presentation (RSVP) KW - event-related potentials (ERP) KW - N400 KW - path analysis Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-57212 ER -