TY  - JOUR
A1  - Engbert, Ralf
A1  - Trukenbrod, Hans Arne
A1  - Barthelme, Simon
A1  - Wichmann, Felix A.
T1  - Spatial statistics and attentional dynamics in scene viewing
JF  - Journal of vision
N2  - In humans and in foveated animals visual acuity is highly concentrated at the center of gaze, so that choosing where to look next is an important example of online, rapid decision-making. Computational neuroscientists have developed biologically-inspired models of visual attention, termed saliency maps, which successfully predict where people fixate on average. Using point process theory for spatial statistics, we show that scanpaths contain, however, important statistical structure, such as spatial clustering on top of distributions of gaze positions. Here, we develop a dynamical model of saccadic selection that accurately predicts the distribution of gaze positions as well as spatial clustering along individual scanpaths. Our model relies on activation dynamics via spatially-limited (foveated) access to saliency information, and, second, a leaky memory process controlling the re-inspection of target regions. This theoretical framework models a form of context-dependent decision-making, linking neural dynamics of attention to behavioral gaze data.
KW  - scene perception
KW  - eye movements
KW  - attention
KW  - saccades
KW  - modeling
KW  - spatial statistics
Y1  - 2015
U6  - https://doi.org/10.1167/15.1.14
SN  - 1534-7362
VL  - 15
IS  - 1
PB  - Association for Research in Vision and Opthalmology
CY  - Rockville
ER  - 
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  -