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Visual backward masking: Modeling spatial and temporal aspects.

Hermens F, Ernst U - Adv Cogn Psychol (2008)

Bottom Line: In modeling visual backward masking, the focus has been on temporal effects.Although interesting effects of the spatial layout of the mask have been found, only a few attempts have been made to model these phenomena.We argue that for better understanding of visual masking, it is vitally important to consider the interplay of spatial and temporal factors together in one single model.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Psychophysics, Brain Mind Institutem, Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland.

ABSTRACT
In modeling visual backward masking, the focus has been on temporal effects. More specifically, an explanation has been sought as to why strongest masking can occur when the mask is delayed with respect to the target. Although interesting effects of the spatial layout of the mask have been found, only a few attempts have been made to model these phenomena. Here, we elaborate a structurally simple model which employs lateral excitation and inhibition together with different neural time scales to explain many spatial and temporal aspects of backward masking. We argue that for better understanding of visual masking, it is vitally important to consider the interplay of spatial and temporal factors together in one single model.

No MeSH data available.


Stimulus sequence (A) and simulation results (B) of data presented by							Herzog et al. (2001). The small							red horizontal bars indicate where the activity of the trace drops below							a particular threshold. A Vernier target was masked by a grating							consisting of a five-element center and a 20-element surround, which							were presented at different onset times. Once presented, the stimulus							remained on the screen until 300 ms after target offset. The model							correctly predicts that the target strength remains strongest for							simultaneous onset of the mask’s center and surround.
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Figure 8: Stimulus sequence (A) and simulation results (B) of data presented by Herzog et al. (2001). The small red horizontal bars indicate where the activity of the trace drops below a particular threshold. A Vernier target was masked by a grating consisting of a five-element center and a 20-element surround, which were presented at different onset times. Once presented, the stimulus remained on the screen until 300 ms after target offset. The model correctly predicts that the target strength remains strongest for simultaneous onset of the mask’s center and surround.

Mentions: As discussed before, a grating of five elements is a stronger mask than one consisting of 25 elements (Herzog, Fahle, & Koch, 2001). Here, we will show simulation results in which the relative onset of the five central elements and the 20 surrounding elements of a 25-element mask was varied. Figure 8A shows the sequences used in the experiment by Herzog et al. (2001) . For negative SOAs, the 20 surrounding elements of the mask preceded the five central elements. For positive SOAs, the central five elements were presented before the surrounding 20 elements. At zero SOA, all 25 elements were presented simultaneously. In the experiment, Vernier offset discrimination thresholds were found to be minimal for an SOA equal to zero, and increased with SOA (either positive or negative).


Visual backward masking: Modeling spatial and temporal aspects.

Hermens F, Ernst U - Adv Cogn Psychol (2008)

Stimulus sequence (A) and simulation results (B) of data presented by							Herzog et al. (2001). The small							red horizontal bars indicate where the activity of the trace drops below							a particular threshold. A Vernier target was masked by a grating							consisting of a five-element center and a 20-element surround, which							were presented at different onset times. Once presented, the stimulus							remained on the screen until 300 ms after target offset. The model							correctly predicts that the target strength remains strongest for							simultaneous onset of the mask’s center and surround.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2864987&req=5

Figure 8: Stimulus sequence (A) and simulation results (B) of data presented by Herzog et al. (2001). The small red horizontal bars indicate where the activity of the trace drops below a particular threshold. A Vernier target was masked by a grating consisting of a five-element center and a 20-element surround, which were presented at different onset times. Once presented, the stimulus remained on the screen until 300 ms after target offset. The model correctly predicts that the target strength remains strongest for simultaneous onset of the mask’s center and surround.
Mentions: As discussed before, a grating of five elements is a stronger mask than one consisting of 25 elements (Herzog, Fahle, & Koch, 2001). Here, we will show simulation results in which the relative onset of the five central elements and the 20 surrounding elements of a 25-element mask was varied. Figure 8A shows the sequences used in the experiment by Herzog et al. (2001) . For negative SOAs, the 20 surrounding elements of the mask preceded the five central elements. For positive SOAs, the central five elements were presented before the surrounding 20 elements. At zero SOA, all 25 elements were presented simultaneously. In the experiment, Vernier offset discrimination thresholds were found to be minimal for an SOA equal to zero, and increased with SOA (either positive or negative).

Bottom Line: In modeling visual backward masking, the focus has been on temporal effects.Although interesting effects of the spatial layout of the mask have been found, only a few attempts have been made to model these phenomena.We argue that for better understanding of visual masking, it is vitally important to consider the interplay of spatial and temporal factors together in one single model.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Psychophysics, Brain Mind Institutem, Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland.

ABSTRACT
In modeling visual backward masking, the focus has been on temporal effects. More specifically, an explanation has been sought as to why strongest masking can occur when the mask is delayed with respect to the target. Although interesting effects of the spatial layout of the mask have been found, only a few attempts have been made to model these phenomena. Here, we elaborate a structurally simple model which employs lateral excitation and inhibition together with different neural time scales to explain many spatial and temporal aspects of backward masking. We argue that for better understanding of visual masking, it is vitally important to consider the interplay of spatial and temporal factors together in one single model.

No MeSH data available.