the role of
figural context & attention
in masking
identification task
A. Williams and Weisstein 1978
identification task
A. Williams and Weisstein 1978
identification task
A. Williams and Weisstein 1978
« Consequently, as well as relying on bottom-up activation, the perceptual process may also incorporate a top-down feedbackactivity or a same-level horizontal modulation between therepresentations of context and local features. »
Breitmeyer and ögmen 2006
target-mask integration
A. Williams and Weisstein 1981
depth connectedness
target-mask integration
A. Williams and Weisstein 1981
depth connectedness
target-mask integration
A. Williams and Weisstein 1981
depth connectedness
other gestalt factors also modulating masking- collinearity (decreased masking)- symmetry (increased masking)- similarity (increased masking)
target-only integration
Ramachandran and Cobb 1995, experiment 1
target-only integration
Ramachandran and Cobb 1995, experiment 1
target-only integration
Ramachandran and Cobb 1995, experiment 2
Constant SOA = 116 ms
Subjective rating of visibility:Attending squares: 1.17Attending circles: 4.08
conclusion (?)
figural context modulates the masking function ...
... but !
some researchers may have combined selective attention and grouping
others have confounded space- or location-based attention with object- or configuration-based attention
conclusion (?)
figural context modulates the masking function ...
... but !
some researchers may have combined selective attention and grouping
others have confounded space- or location-based attention with object- or configuration-based attention ...
... therefore
unclear if modulation of masking is due to grouping or space/object-based attention
space-based attentional effects
Enns and DiLollo 1997, experiment 1
space-based attentional effects
Enns and DiLollo 1997, experiment 1
masking with four-dot mask not onlydue to low-level contour interactions
space-based attentional effects
Enns and DiLollo 1997, experiment 2
masking insensitive to contour proximity at parafoveal locations
space-based attentional effects
Enns and DiLollo 1997, experiment 3
four-dot masking increased with number of targets
space-based attentional effects
Enns and DiLollo 1997
conclusions
• four-dot masking cannot be explained by contour-based mechanisms commonly used to explain meta-contrast.• one explanation might be incomplete focusing of spatial attention
space-based attentional effects
Enns and DiLollo 1997
conclusions
• four-dot masking cannot be explained by contour-based mechanisms commonly used to explain meta-contrast.• one explanation might be incomplete focusing of spatial attention
« ... these data suggest that the need for observers to distribute their attention over all three targets, prior to the onset of the four dots, resulted in masking of even the foveated target shape. »
space-based attentional effects
Tata 2002, experiment 1
masking increased with number of targets
space-based attentional effects
Tata 2002, experiment 2
correct attentional cue decreased masking
space-based attentional effects
Tata 2002, experiment 3
pop-out effect reduced masking
space-based attentional effects
Tata 2002
conclusions
• results suggest that theories based on low-level processes early in visual system is insufficient to explain metacontrast masking.• visual selective attention plays an important role in metacontrast masking
object/feature-based attentional effects
inattentional blindness, is an observed phenomenon of the inability to perceive features in a visual scene when the observer is not attending to them.
object/feature-based attentional effects
inattentional blindness, is an observed phenomenon of the inability to perceive features in a visual scene when the observer is not attending to them.
object/feature-based attentional effects
inattentional blindness, is an observed phenomenon of the inability to perceive features in a visual scene when the observer is not attending to them.
more familiar, typical, or salient visual objects have higher probability of resisting IB, which leads to less masking compared to items less resistant to IB.
central attentional effects
mechanisms of masking:
• integration through common synthesis • interchannel inhibition• replacement principle
Michaels and Turvey 1979
central attentional effects
mechanisms of masking:• camouflage masking • interruption
Enns and DiLollo 1997
another role of attention:increase spatiotemporal resolution of objects presented to nonfoveal regions
masking by four dots possible because:• unattended targets are coded with low spatiotemporal
resolution • attended four-dot mask have an advantage when
competing for higher level mechanisms involved in object recognition
central attentional effects
mechanisms of masking:• camouflage masking • interruption
Enns and DiLollo 1997
another role of attention:increase spatiotemporal resolution of objects presented to nonfoveal regions
masking by four dots possible because:• unattended targets are coded with low spatiotemporal
resolution • attended four-dot mask have an advantage when
competing for higher level mechanisms involved in object recognition
Object substitution masking
conclusions
figural context and masking
• gestalt factors influence masking• target integrated in an object (2D/3D) is less masked• different temporal properties governs operation of
different gestalt factors of figural organization• target being part of larger gestalt is masked less than
when being part of a meaningless arrangement
Breitmeyer and ögmen 2006
conclusions
figural context and masking
• gestalt factors influence masking• target integrated in an object (2D/3D) is less masked• different temporal properties governs operation of
different gestalt factors of figural organization• target being part of larger gestalt is masked less than
when being part of a meaningless arrangement
attention and masking
• attending features or location of targets enhances visibility of the target
• centrally controlled attention processes mediate transfer of information from iconic levels to post-iconic levels predicts level of performance
Breitmeyer and ögmen 2006
conclusions
both figural context and attention affects visibility of a target, but this is a general feature of attention/figural context when studied in a variety of other experimental paradigms
Breitmeyer and ögmen 2006
conclusions
both figural context and attention affects visibility of a target, but this is a general feature of attention/figural context when studied in a variety of other experimental paradigms
« Thus both top-down influences on backward masking can be viewed simply as modulators of masking analogous to the bottom-up modulatory effects produced by varying certain physical parameters of the target and mask stimuli »
Breitmeyer and ögmen 2006
thank you
for your attention
at the lecture