attention and spatial resolution
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Attention and spatial resolution. Landolt squares. Vernier. Broken lines. : pTRANSCRIPT
Attention and spatial resolution
2
Spatial resolution
• Our ability to resolve small details (spatial resolution) is maximal at fovea and declines as we move away from fixation
• Most everyday life tasks benefit from heightened resolution
Antis, 1974
Landolt squares Broken lines Vernier
Pe
rfo
rma
nce
Eccentricity (in deg)
Acuity tasks:
Yeshurun & Carrasco, 1998
Attention improves performance in tasks limited by the visual system‘s spatial resolution, which decreases with eccentricity:
• Visual search• Acuity tasks• Texture segmentation
Attention and spatial resolution
• Performance decreases with target eccentricity
• Attention reduces this performance decrement, consistent with enhanced spatial resolution
Carrasco & Yeshurun, 1998
Visual search
• Attention improves performance in Landolt-square (acuity) and Vernier (hyperacuity) tasks
• Effect increases with eccentricity
Yeshurun & Carrasco, 1999
Acuity task
attention decreases gap threshold at cued location and increase it at uncued location
Montagna, Pestilli, & Carrasco, 2009
Acuity task
• However, heightened resolution is not always optimal
Spatial resolution
+
performancepeak
periphery
Per
form
ance
Eccentricityfovea
Texture segmentation task
Average spatial filter size
+
Texture segmentation task
e.g., Gurnsey et al. 1996; Joffe & Scialfa 1995; Kehrer 1989, 1997; Morikawa 2000; Potechin & Gurnsey 2003
performancepeak
Per
form
ance
periphery
Eccentricityfovea
Performance due to the mismatch between texture scale and average size of spatial filters as a function of eccentricity.
Central performance drop (CPD): due to spatial resolution being too high at central locations.
resolution too high
resolution too low
LARGE TEXTURE SCALE(viewing distance: 28 cm)
SMALL TEXTURE SCALE(viewing distance: 57 cm)
valid
neutral
10
Attention & Texture segmentation
• Exogenous attention automatically enhances resolution, even when it impairs performance
e.g., Yeshurun & Carrasco 1998; 2000; Talgar & Carrasco, 2002
High Spatial Frequencies
Low Spatial Frequencies
Baseline
validneutral
• Exogenous attention enhances resolution by increasing the sensitivity of high spatial frequency selective filters:
- adapting to high (but not to low spatial frequencies) eliminates the CPD and the central attentional impairment
Carrasco, Loula & Ho, 2006
Attention & Texture segmentation
12
small texture scale(viewing distance: 100 cm)
valid
neutral
large texture scale(viewing distance: 50 cm)
validneutral
Attention & Texture segmentation
• Endogenous attention benefits performance at all eccentricities, suggesting a more flexible mechanism
Yeshurun, Montagna & Carrasco 2008
Performance at peripheral locations improves
Spatial resolution
FLEXIBILITY?
Performance at central locations impairs improves
improves
either increased or decreased?
EXOGENOUS ENDOGENOUS
_
+
Eccentricity
AUTOMATICITY
_
+
Pe
rfo
rma
nce
increase
decrease?
Spatial resolution:
_
+
Eccentricity
Yeshurun, Montagna & Carrasco (2008)Carrasco, Loula & Ho (2006)Yeshurun & Carrasco (1998; 2000)
validneutral
increased
small filterssensitivity