attention and spatial resolution

13
Attention and spatial resolution

Upload: lillith-best

Post on 30-Dec-2015

41 views

Category:

Documents


0 download

DESCRIPTION

Attention and spatial resolution. Landolt squares. Vernier. Broken lines. : p

TRANSCRIPT

Page 1: Attention and spatial resolution

Attention and spatial resolution

Page 2: 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

Page 3: Attention and spatial resolution

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

Page 4: Attention and spatial resolution

• Performance decreases with target eccentricity

• Attention reduces this performance decrement, consistent with enhanced spatial resolution

Carrasco & Yeshurun, 1998

Visual search

Page 5: Attention and spatial resolution

• Attention improves performance in Landolt-square (acuity) and Vernier (hyperacuity) tasks

• Effect increases with eccentricity

Yeshurun & Carrasco, 1999

Acuity task

Page 6: Attention and spatial resolution

attention decreases gap threshold at cued location and increase it at uncued location

Montagna, Pestilli, & Carrasco, 2009

Acuity task

Page 7: Attention and spatial resolution

• However, heightened resolution is not always optimal

Spatial resolution

Page 8: Attention and spatial resolution

+

performancepeak

periphery

Per

form

ance

Eccentricityfovea

Texture segmentation task

Page 9: Attention and spatial resolution

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

Page 10: Attention and spatial resolution

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

Page 11: Attention and spatial resolution

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

Page 12: Attention and spatial resolution

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

Page 13: Attention and spatial resolution

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