TY  - GEN
A1  - Laubrock, Jochen
A1  - Engbert, Ralf
A1  - Cajar, Anke
T1  - Gaze-contingent manipulation of the FVF demonstrates the importance of fixation duration for explaining search behavior
T2  - Behavioral and brain sciences : an international journal of current research and theory with open peer commentary
N2  - Hulleman & Olivers' (H&O's) model introduces variation of the functional visual field (FVF) for explaining visual search behavior. Our research shows how the FVF can be studied using gaze-contingent displays and how FVF variation can be implemented in models of gaze control. Contrary to H&O, we believe that fixation duration is an important factor when modeling visual search behavior.
Y1  - 2017
U6  - https://doi.org/10.1017/S0140525X16000145
SN  - 0140-525X
SN  - 1469-1825
VL  - 40
SP  - 31
EP  - 32
PB  - Cambridge Univ. Press
CY  - New York
ER  - 
TY  - GEN
A1  - Cajar, Anke
A1  - Engbert, Ralf
A1  - Laubrock, Jochen
T1  - Eye movements during gaze-contingent spatial-frequency filtering of real-world scenes: Effects of filter location, cutoff, and size
T2  - Perception
Y1  - 2016
SN  - 0301-0066
SN  - 1468-4233
VL  - 45
SP  - 126
EP  - 126
PB  - Sage Publ.
CY  - London
ER  - 
TY  - GEN
A1  - Kruegel, Andre
A1  - Engbert, Ralf
T1  - Statistics of microsaccades indicate early frequency effects during visual word recognition
T2  - Perception
Y1  - 2016
SN  - 0301-0066
SN  - 1468-4233
VL  - 45
SP  - 127
EP  - 127
PB  - Sage Publ.
CY  - London
ER  - 
TY  - GEN
A1  - Schütt, Heiko Herbert
A1  - Rothkegel, Lars Oliver Martin
A1  - Trukenbrod, Hans Arne
A1  - Engbert, Ralf
A1  - Wichmann, Felix A.
T1  - Predicting fixation densities over time from early visual processing
T2  - Perception
N2  - Bottom-up saliency is often cited as a factor driving the choice of fixation locations of human observers, based on the (partial) success of saliency models to predict fixation densities in free viewing. However, these observations are only weak evidence for a causal role of bottom-up saliency in natural viewing behaviour. To test bottom-up saliency more directly, we analyse the performance of a number of saliency models---including our own saliency model based on our recently published model of early visual processing (Schütt & Wichmann, 2017, JoV)---as well as the theoretical limits for predictions over time. On free viewing data our model performs better than classical bottom-up saliency models, but worse than the current deep learning based saliency models incorporating higher-level information like knowledge about objects. However, on search data all saliency models perform worse than the optimal image independent prediction. We observe that the fixation density in free viewing is not stationary over time, but changes over the course of a trial. It starts with a pronounced central fixation bias on the first chosen fixation, which is nonetheless influenced by image content. Starting with the 2nd to 3rd fixation, the fixation density is already well predicted by later densities, but more concentrated. From there the fixation distribution broadens until it reaches a stationary distribution around the 10th fixation. Taken together these observations argue against bottom-up saliency as a mechanistic explanation for eye movement control after the initial orienting reaction in the first one to two saccades, although we confirm the predictive value of early visual representations for fixation locations. The fixation distribution is, first, not well described by any stationary density, second, is predicted better when including object information and, third, is badly predicted by any saliency model in a search task.
Y1  - 2019
SN  - 0301-0066
SN  - 1468-4233
VL  - 48
SP  - 64
EP  - 65
PB  - Sage Publ.
CY  - London
ER  - 
TY  - GEN
A1  - Schwetlick, Lisa
A1  - Trukenbrod, Hans Arne
A1  - Engbert, Ralf
T1  - The Influence of Visual Long Term Memory on Eye Movements During Scene Viewing
T2  - Perception
Y1  - 2019
SN  - 0301-0066
SN  - 1468-4233
VL  - 48
IS  - S1
SP  - 138
EP  - 138
PB  - Sage Publ.
CY  - London
ER  -