How exogenous spatial attention affects visual representation

Abstract

Orienting covert spatial attention to a target location enhances visual sensitivity and benefits performance in many visual tasks. How these attention-related improvements in performance affect the underlying visual representation of low-level visual features is not fully understood. Here we focus on characterizing how exogenous spatial attention affects the feature representations of orientation and spatial frequency. We asked observers to detect a vertical grating embedded in noise and performed psychophysical reverse correlation. Doing so allowed us to make comparisons with previous studies that utilized the same task and analysis to assess how endogenous attention and presaccadic modulations affect visual representations. We found that exogenous spatial attention improved performance and enhanced the gain of the target orientation without affecting orientation tuning width. Moreover, we found no change in spatial frequency tuning. We conclude that covert exogenous spatial attention alters performance by strictly boosting gain of orientation-selective filters, much like covert endogenous spatial attention.

Differential impact of exogenous and endogenous attention on the contrast sensitivity function across eccentricity

“…These novel findings advance our understanding of the effects of exogenous and endogenous attention on a fundamental measure of visual function, contrast sensitivity. Although many previous studies have demonstrated that both exogenous attention ( Barbot et al, 2011 ; Barbot et al, 2012 ; Cameron et al, 2002 ; Carrasco et al, 2000 ; Carrasco & McElree, 2001 ; Fernández et al, 2019 ; Foley & Schwarz, 1998 ; Herrmann et al, 2010 ; Ling & Carrasco, 2006b ; Liu et al, 2005 ; Morgan et al, 1998 ; Pestilli et al, 2007 ; Pestilli & Carrasco, 2005 ; Smith et al, 2004 ; Solomon, Lavie, & Morgan, 2004 ) and endogenous attention ( Barbot et al, 2012 ; Dosher & Lu, 2000a , 2000b ; Herrmann et al, 2010 ; Huang & Dobkins, 2005 ; Lee et al, 1997 , 1999 ; Ling & Carrasco, 2006a , 2006b ; Lu et al, 2002 ; Lu & Dosher, 1998 , 2000 , 2004 ; Morrone et al, 2002 , 2004 ) improve contrast sensitivity, we characterized their effects across SF and eccentricity to reveal that each operates differently relative to the constraints of the visual system at each eccentricity.…”

“…The current findings also provide possible explanations for discrepant findings in the literature regarding the effects of exogenous attention on contrast sensitivity across SF. A recent study (Fernández et al, 2019) used psychophysical reverse correlation to assess how exogenous attention altered sensitivity to orientation and SF to improve task performance. The authors found that behavioral improvements were not associated with enhanced sensitivity to SFs, which would seemingly conflict with the enhancements observed here.…”

“…Contrast sensitivity, the ability to discriminate visual patterns from a uniform background, is a fundamental measure of visual function that depends substantially on the pattern's spatial frequency (SF) and eccentricity ( Campbell & Robson, 1968 ; De Valois, Morgan, Snodderly, 1974 ; Hilz & Cavonius, 1974 ; Kelly, 1977 ; Owsley, 2003 ; Robson, 1966 ; Robson & Graham, 1981 ; Rovamo Virsu, & Näsänen, 1978 ; Virsu & Rovamo, 1979 ). Covert spatial attention (henceforth attention)—the prioritization of discrete spatial locations in the absence of eye movements—enhances contrast sensitivity for a wide range of spatial frequencies and at several eccentricities ( Barbot, Landy, & Carrasco, 2011 , Barbot, Landy, & Carrasco, 2012 ; Cameron, Tai, & Carrasco, 2002 ; Carrasco, Penpeci-Talgar, & Eckstein, 2000 ; Carrasco & McElree, 2001 ; Dosher & Lu, 2000a ; Dosher & Lu, 2000b ; Fernández et al, 2019 ; Foley & Schwarz, 1998 ; Herrmann, Montaser-Kouhsari, Carrasco, & Heeger, 2010 ; Huang & Dobkins, 2005 ; Lee et al, 1997 ; Lee, Itti, Koch, & Braun, 1999 ; Ling & Carrasco, 2006a ; Ling & Carrasco, 2006b ; Liu, Pestilli, & Carrasco, 2005 ; Lu, Lesmes, & Dosher, 2002 ; Lu & Dosher, 1998 ; Lu & Dosher, 2000 ; Morgan, Ward, & Castet, et al,1998 ; Morrone, Denti, & Spinelli, 2002 ; Morrone, Denti, & Spinelli, 2004 ; Pestilli, Viera, & Carrasco, 2007 ; Pestilli & Carrasco, 2005 ; Smith, Wolfgang, & Sinclair, 2004 ; Solomon, 2004 ; Solomon, Lavie, & Morgan, 1997 ; for reviews see, Carrasco, 2006 , Carrasco, 2011 ; Carrasco, 2014 ). However, very few studies have directly compared the effects of exogenous (involuntary) and endogenous (voluntary) attention on contrast sensitivity ( Barbot et al, 2012 ; Herrmann et al, 2010 ; Ling & Carrasco, 2006b ; Lu & Dosher, 2000 ), and no single study has jointly man...…”

“…Attention has been widely demonstrated to increase contrast sensitivity across the CSF ( Cameron et al, 2002 ; Carrasco et al, 2000 ) and separately at several eccentricities ( Barbot et al, 2011 ; Barbot et al, 2012 ; Carrasco, 2006 ; Carrasco & McElree, 2001 ; Dosher & Lu, 2000a , 2000b ; Fernández, Li, & Carrasco, 2019 ; Foley & Schwarz, 1998 ; Herrmann et al, 2010 ; Huang & Dobkins, 2005 ; Lee, Koch, & Braun, 1997 ; Lee, Koch, & Braun, 1999 ; Ling & Carrasco, 2006a ; Ling & Carrasco, 2006b ; Liu et al, 2005 ; Lu et al, 2002 ; Lu & Dosher, 1998 ; Lu & Dosher, 2000 ; Morgan et al, 1998 ; Morrone et al, 2002 , 2004 ; Pestilli et al, 2007 ; Pestilli & Carrasco, 2005 ; Smith et al, 2004 ; Solomon, 2004 ; Solomon et al, 1997 ). On the perceptual level, such attentional modulation is governed by two mechanisms: signal enhancement and external noise reduction.…”

Time-dependent inhibition of covert shift of attention

“…Numerous studies have shown perceptual benefits at locations that have been previously cued, even when no eye movement is made, confirming that it is possible to orient attention covertly (Posner 1980; see: Posner 2015 for a review). These studies have mostly used simple detection responses, but covert orienting can also improve the discimination of spatial frequency and lower the contrast threshold for orientation discimination (Barbot et al 2012; Cameron et al 2002; Carrasco 2011; Fernández et al 2019; Lee et al 1999; Pestilli and Carrasco 2005; Solomon 2004). Given the strong similarities between the overt and covert process, we ask whether the phenomenon of saccadic inhibition, which arises with striking regularity in overt responses, extends to covert orienting behaviour.…”