@phdthesis{Cajar2016, author = {Cajar, Anke}, title = {Eye-movement control during scene viewing}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-395536}, school = {Universit{\"a}t Potsdam}, pages = {vii, 133}, year = {2016}, abstract = {Eye movements serve as a window into ongoing visual-cognitive processes and can thus be used to investigate how people perceive real-world scenes. A key issue for understanding eye-movement control during scene viewing is the roles of central and peripheral vision, which process information differently and are therefore specialized for different tasks (object identification and peripheral target selection respectively). Yet, rather little is known about the contributions of central and peripheral processing to gaze control and how they are coordinated within a fixation during scene viewing. Additionally, the factors determining fixation durations have long been neglected, as scene perception research has mainly been focused on the factors determining fixation locations. The present thesis aimed at increasing the knowledge on how central and peripheral vision contribute to spatial and, in particular, to temporal aspects of eye-movement control during scene viewing. In a series of five experiments, we varied processing difficulty in the central or the peripheral visual field by attenuating selective parts of the spatial-frequency spectrum within these regions. Furthermore, we developed a computational model on how foveal and peripheral processing might be coordinated for the control of fixation duration. The thesis provides three main findings. First, the experiments indicate that increasing processing demands in central or peripheral vision do not necessarily prolong fixation durations; instead, stimulus-independent timing is adapted when processing becomes too difficult. Second, peripheral vision seems to play a prominent role in the control of fixation durations, a notion also implemented in the computational model. The model assumes that foveal and peripheral processing proceed largely in parallel and independently during fixation, but can interact to modulate fixation duration. Thus, we propose that the variation in fixation durations can in part be accounted for by the interaction between central and peripheral processing. Third, the experiments indicate that saccadic behavior largely adapts to processing demands, with a bias of avoiding spatial-frequency filtered scene regions as saccade targets. We demonstrate that the observed saccade amplitude patterns reflect corresponding modulations of visual attention. The present work highlights the individual contributions and the interplay of central and peripheral vision for gaze control during scene viewing, particularly for the control of fixation duration. Our results entail new implications for computational models and for experimental research on scene perception.}, language = {en} } @misc{CajarEngbertLaubrock2022, author = {Cajar, Anke and Engbert, Ralf and Laubrock, Jochen}, title = {Potsdam Eye-Movement Corpus for Scene Memorization and Search With Color and Spatial-Frequency Filtering}, series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, journal = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, issn = {1866-8364}, doi = {10.25932/publishup-56318}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-563184}, pages = {1 -- 7}, year = {2022}, language = {en} } @article{CajarEngbertLaubrock2022, author = {Cajar, Anke and Engbert, Ralf and Laubrock, Jochen}, title = {Potsdam Eye-Movement Corpus for Scene Memorization and Search With Color and Spatial-Frequency Filtering}, series = {Frontiers in psychology / Frontiers Research Foundation}, volume = {13}, journal = {Frontiers in psychology / Frontiers Research Foundation}, publisher = {Frontiers Research Foundation}, address = {Lausanne, Schweiz}, issn = {1664-1078}, doi = {10.3389/fpsyg.2022.850482}, pages = {1 -- 7}, year = {2022}, language = {en} } @article{CajarEngbertLaubrock2016, author = {Cajar, Anke and Engbert, Ralf and Laubrock, Jochen}, title = {Spatial frequency processing in the central and peripheral visual field during scene viewing}, series = {Vision research : an international journal for functional aspects of vision.}, volume = {127}, journal = {Vision research : an international journal for functional aspects of vision.}, publisher = {Elsevier}, address = {Oxford}, issn = {0042-6989}, doi = {10.1016/j.visres.2016.05.008}, pages = {186 -- 197}, year = {2016}, abstract = {Visuospatial attention and gaze control depend on the interaction of foveal and peripheral processing. The foveal and peripheral regions of the visual field are differentially sensitive to parts of the spatial frequency spectrum. In two experiments, we investigated how the selective attenuation of spatial frequencies in the central or the peripheral visual field affects eye-movement behavior during real-world scene viewing. Gaze-contingent low-pass or high-pass filters with varying filter levels (i.e., cutoff frequencies; Experiment 1) or filter sizes (Experiment 2) were applied. Compared to unfiltered control conditions, mean fixation durations increased most with central high-pass and peripheral low-pass filtering. Increasing filter size prolonged fixation durations with peripheral filtering, but not with central filtering. Increasing filter level prolonged fixation durations with low-pass filtering, but not with high-pass filtering. These effects indicate that fixation durations are not always longer under conditions of increased processing difficulty. Saccade amplitudes largely adapted to processing difficulty: amplitudes increased with central filtering and decreased with peripheral filtering; the effects strengthened with increasing filter size and filter level. In addition, we observed a trade-off between saccade timing and saccadic selection, since saccade amplitudes were modulated when fixation durations were unaffected by the experimental manipulations. We conclude that interactions of perception and gaze control are highly sensitive to experimental manipulations of input images as long as the residual information can still be accessed for gaze control. (C) 2016 Elsevier Ltd. All rights reserved.}, language = {en} } @misc{CajarEngbertLaubrock2016, author = {Cajar, Anke and Engbert, Ralf and Laubrock, Jochen}, title = {Eye movements during gaze-contingent spatial-frequency filtering of real-world scenes: Effects of filter location, cutoff, and size}, series = {Perception}, volume = {45}, journal = {Perception}, publisher = {Sage Publ.}, address = {London}, issn = {0301-0066}, pages = {126 -- 126}, year = {2016}, language = {en} } @article{CajarEngbertLaubrock2020, author = {Cajar, Anke and Engbert, Ralf and Laubrock, Jochen}, title = {How spatial frequencies and color drive object search in real-world scenes}, series = {Journal of vision}, volume = {20}, journal = {Journal of vision}, number = {7}, publisher = {Association for Research in Vision and Opthalmology}, address = {Rockville}, issn = {1534-7362}, doi = {10.1167/jov.20.7.8}, pages = {16}, year = {2020}, abstract = {When studying how people search for objects in scenes, the inhomogeneity of the visual field is often ignored. Due to physiological limitations, peripheral vision is blurred and mainly uses coarse-grained information (i.e., low spatial frequencies) for selecting saccade targets, whereas high-acuity central vision uses fine-grained information (i.e., high spatial frequencies) for analysis of details. Here we investigated how spatial frequencies and color affect object search in real-world scenes. Using gaze-contingent filters, we attenuated high or low frequencies in central or peripheral vision while viewers searched color or grayscale scenes. Results showed that peripheral filters and central high-pass filters hardly affected search accuracy, whereas accuracy dropped drastically with central low-pass filters. Peripheral filtering increased the time to localize the target by decreasing saccade amplitudes and increasing number and duration of fixations. The use of coarse-grained information in the periphery was limited to color scenes. Central filtering increased the time to verify target identity instead, especially with low-pass filters. We conclude that peripheral vision is critical for object localization and central vision is critical for object identification. Visual guidance during peripheral object localization is dominated by low-frequency color information, whereas high-frequency information, relatively independent of color, is most important for object identification in central vision.}, language = {en} } @article{CajarSchneeweissEngbertetal.2016, author = {Cajar, Anke and Schneeweiss, Paul and Engbert, Ralf and Laubrock, Jochen}, title = {Coupling of attention and saccades when viewing scenes with central and peripheral degradation}, series = {Journal of vision}, volume = {16}, journal = {Journal of vision}, publisher = {Association for Research in Vision and Opthalmology}, address = {Rockville}, issn = {1534-7362}, doi = {10.1167/16.2.8}, pages = {19}, year = {2016}, abstract = {Degrading real-world scenes in the central or the peripheral visual field yields a characteristic pattern: Mean saccade amplitudes increase with central and decrease with peripheral degradation. Does this pattern reflect corresponding modulations of selective attention? If so, the observed saccade amplitude pattern should reflect more focused attention in the central region with peripheral degradation and an attentional bias toward the periphery with central degradation. To investigate this hypothesis, we measured the detectability of peripheral (Experiment 1) or central targets (Experiment 2) during scene viewing when low or high spatial frequencies were gaze-contingently filtered in the central or the peripheral visual field. Relative to an unfiltered control condition, peripheral filtering induced a decrease of the detection probability for peripheral but not for central targets (tunnel vision). Central filtering decreased the detectability of central but not of peripheral targets. Additional post hoc analyses are compatible with the interpretation that saccade amplitudes and direction are computed in partial independence. Our experimental results indicate that task-induced modulations of saccade amplitudes reflect attentional modulations.}, language = {en} } @article{CajarSchneeweissEngbertetal.2016, author = {Cajar, Anke and Schneeweiß, Paul and Engbert, Ralf and Laubrock, Jochen}, title = {Coupling of attention and saccades when viewing scenes with central and peripheral degradation}, series = {Journal of Vision}, volume = {16}, journal = {Journal of Vision}, number = {2}, publisher = {ARVO}, address = {Rockville, Md.}, issn = {1534-7362}, doi = {10.1167/16.2.8}, pages = {1 -- 19}, year = {2016}, abstract = {Degrading real-world scenes in the central or the peripheral visual field yields a characteristic pattern: Mean saccade amplitudes increase with central and decrease with peripheral degradation. Does this pattern reflect corresponding modulations of selective attention? If so, the observed saccade amplitude pattern should reflect more focused attention in the central region with peripheral degradation and an attentional bias toward the periphery with central degradation. To investigate this hypothesis, we measured the detectability of peripheral (Experiment 1) or central targets (Experiment 2) during scene viewing when low or high spatial frequencies were gaze-contingently filtered in the central or the peripheral visual field. Relative to an unfiltered control condition, peripheral filtering induced a decrease of the detection probability for peripheral but not for central targets (tunnel vision). Central filtering decreased the detectability of central but not of peripheral targets. Additional post hoc analyses are compatible with the interpretation that saccade amplitudes and direction are computed in partial independence. Our experimental results indicate that task-induced modulations of saccade amplitudes reflect attentional modulations.}, language = {en} } @misc{CajarSchneeweissEngelbertetal.2016, author = {Cajar, Anke and Schneeweiß, Paul and Engelbert, Ralf and Laubrock, Jochen}, title = {Coupling of attention and saccades when viewing scenes with central and peripheral degradation}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-394918}, pages = {19}, year = {2016}, abstract = {Degrading real-world scenes in the central or the peripheral visual field yields a characteristic pattern: Mean saccade amplitudes increase with central and decrease with peripheral degradation. Does this pattern reflect corresponding modulations of selective attention? If so, the observed saccade amplitude pattern should reflect more focused attention in the central region with peripheral degradation and an attentional bias toward the periphery with central degradation. To investigate this hypothesis, we measured the detectability of peripheral (Experiment 1) or central targets (Experiment 2) during scene viewing when low or high spatial frequencies were gaze-contingently filtered in the central or the peripheral visual field. Relative to an unfiltered control condition, peripheral filtering induced a decrease of the detection probability for peripheral but not for central targets (tunnel vision). Central filtering decreased the detectability of central but not of peripheral targets. Additional post hoc analyses are compatible with the interpretation that saccade amplitudes and direction are computed in partial independence. Our experimental results indicate that task-induced modulations of saccade amplitudes reflect attentional modulations.}, language = {en} } @inproceedings{LaubrockCajarEngbert2012, author = {Laubrock, Jochen and Cajar, Anke and Engbert, Ralf}, title = {Peripheral spatial frequency processing affects timing and metrics of saccades}, series = {Perception}, volume = {41}, booktitle = {Perception}, publisher = {Sage Publ.}, address = {London}, issn = {0301-0066}, pages = {170 -- 170}, year = {2012}, language = {en} }