the role of figural context

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the role offigural context attentionin
masking
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identification task
A. Williams and Weisstein 1978
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identification task
A. Williams and Weisstein 1978
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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 feedback activity or a
same-level horizontal modulation between
the representations of context and local
features. 
Breitmeyer and ögmen 2006
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target-mask integration
depth connectedness
A. Williams and Weisstein 1981
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target-mask integration
depth connectedness
A. Williams and Weisstein 1981
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target-mask integration
depth connectedness
other gestalt factors also modulating masking -
collinearity (decreased masking) - symmetry
(increased masking) - similarity (increased
masking)
A. Williams and Weisstein 1981
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target-only integration
Ramachandran and Cobb 1995, experiment 1
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target-only integration
Ramachandran and Cobb 1995, experiment 1
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target-only integration
Constant SOA 116 ms Subjective rating of
visibility Attending squares 1.17 Attending
circles 4.08
Ramachandran and Cobb 1995, experiment 2
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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
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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
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space-based attentional effects
Enns and DiLollo 1997, experiment 1
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space-based attentional effects

• masking with four-dot mask not only
• due to low-level contour interactions

Enns and DiLollo 1997, experiment 1
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space-based attentional effects

• masking insensitive to contour
• proximity at parafoveal locations

Enns and DiLollo 1997, experiment 2
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space-based attentional effects

• four-dot masking increased with number of targets

Enns and DiLollo 1997, experiment 3
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space-based attentional effects

• 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

Enns and DiLollo 1997
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space-based attentional effects

• 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.
Enns and DiLollo 1997
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space-based attentional effects
masking increased with number of targets
Tata 2002, experiment 1
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space-based attentional effects
correct attentional cue decreased masking
Tata 2002, experiment 2
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space-based attentional effects
pop-out effect reduced masking
Tata 2002, experiment 3
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space-based attentional effects

• 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

Tata 2002
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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.
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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.
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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.
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central attentional effects

• mechanisms of masking
• integration through common synthesis
• interchannel inhibition
• replacement principle

Michaels and Turvey 1979
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central attentional effects

• mechanisms of masking
• camouflage masking
• interruption

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

Enns and DiLollo 1997
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central attentional effects

• mechanisms of masking
• camouflage masking
• interruption

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
Enns and DiLollo 1997
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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
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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
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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
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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
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thank youfor your attentionat the lecture