Absence of contour linking in peripheral vision

“contour immersed in a random texture [36,83,56,109,108,57,14,11,58], are”

“Another may be that contour linking may be totally absent for peripheral processing ( Hess & Dakin, 1997 ).”

“here referred to as a simple filter model (see [28] for details).”

“Neighboring gratings whose contours are approximately collinear more readily group to form smooth curves than do grating patches consisting of contours that deviate markedly from collinearity (Field, Hayes & Hess, 1993; Kovacs & Julesz, 1993; Hess & Dakin, 1997).”

“Similar were the results in psychophysical studies reporting lower detection thresholds of aligned Gabor patches (Gilbert and Wiesel 1990; Hess and Dakin 1997; Polat and Norcia 1998; Keeble and Hess 1999) with larger response amplitudes and higher contrast sensitivity.”

“…(Bonneh, Sagi, & Polat, 2004, 2007; Levi, Hariharan, & Klein, 2002; Polat, Bonneh, Ma-Naim, Belkin, & Sagi, 2005; Polat, Ma-Naim, Belkin, & Sagi, 2004; Polat, Sagi, & Norcia, 1997), and impaired contour detection (Hess & Dakin, 1997; Kovacs, Polat, Pennefather, Chandna, & Norcia, 2000).”

“2 log units) difference between smooth and star-shaped elliptic configurations, which indicates that similar mechanisms for contour integration at threshold are operative in the periphery (but see [38]).”

“A great deal of research has suggested there is interaction between channels, so one channel’s activity will affect the selective responsiveness of SFs in another channel (Henning, Hertz, & Broadbent, 1975; Nachmias, Sansbury, Vassiley, & Weber, 1973; Nachmias & Weber, 1975; Tolhurst & Barfield, 1978; and, more recent…”

“They are relatively insensitive to the contrast (Hess, Dakin, & Field, 1998) and contrast polarity of contour elements (Field et al., 1993; Hess & Dakin, 1997 ) but are sensitive to their spatial frequency (Dakin & Hess, 1998), degree of phase alignment (Dakin & Hess, 1999), and depth (Hess & Field, 1995).”

“Keywords: Color vision; Isoluminance; Red–green and blue–yellow mechanisms; Contour integration”

“Another possibility is that symmetry detection depends on the foveal specialization of linking mechanisms such as those that mediate the detection of co-aligned features (Hess & Dakin, 1997).”

“This notion is consistent with a growing consensus (Livne & Sagi, 2007; May & Hess, 2007) that the processes that produce crowding may be the same as those that limit contour integration in the periphery (Hess & Dakin, 1997).”

“, 1997), hue (McIlhagga and Mullen, 1996), eccentricity (Hess and Dakin, 1997), number of elements (Moulden, 1994), and closure (Kóvacs and Julesz, 1993; it should be noted that recent evidence suggests that sensitivity to closure may be explained by smoothness constraints on contour integration, see Pettet et al.”

“(8)), provided facilitatory interactions still occur (Hess & Dakin, 1997; Xing & Heeger, 2000).”

“The parameters of the embedded contours, such as length and curvature, prevent the contour from being detected by individual receptive fields (Hess & Dakin, 1997); the responses of multiple local units must be integrated in order to detect the contour.”

“We specifically avoided scaling our stimuli with eccentricity because we wanted to investigate performance at a given spatial scale and eccentricity (though this is not important because this task exhibits scale invariance over the relevant eccentricity range investigated here; Hess & Dakin, 1997).”

“Thus, there was no evidence for an additional penalty for changes in curvature.”

“Finally, the MIRAGE was offered only for processing of 1-D signals and the extension to two dimensions may not be trivial (although Hess and Dakin [23] have reported using a 2-D adaptation of the algorithm, but gave no details).”

“Performance decreases with eccentricity in a variety of tasks (Berkley, Kitterle, & Watkins, 1975; 1995; Gurnsey, Pearson, & Day, 1996; Hess & Dakin, 1997) and varies even at isoeccentric locations causing a horizontalvertical anisotropy (HVA) and a vertical meridian asymmetry (VMA).”

“Hess and colleagues have argued cogently for a strong role for positional uncertainty, in limiting contour integration both in strabismic amblyopia (Hess et al., 1997, 1998) and in peripheral vision ( Hess & Dakin, 1997, 1999 ).”

“While we know that the conditions under which a whole multi-element contour can be signaled by large filters are quite limited (Hess & Dakin, 1997), that is not to say that the response of large filters to pair-wise groupings in the contour might not be important for binding these elements across…”

“This result demonstrates that contour integration follows a scale invariance as previously suggested by Hess and Dakin (1997), who reported that contour detection is constant over a wide range of viewing distances.”

“The position of the contour was jittered up to 2° around the centre of the screen so that its elements appeared in different spots but at roughly the same radius so as to minimize positional uncertainty (e.g., Hess & Dakin, 1997, 1999).”

“Note that individual Gabor elements were sine phase (Hess & Dakin, 1999) not cosine phase as incorrectly reported by Hess and Dakin (1997).”

“Also, arrays of near-collinear Gabor elements become integrated into larger contours, grouping together to form smooth curves which stand out saliently from a background of randomly oriented Gabor elements (Field, Hayes, & Hess, 1993; Hess & Dakin, 1997; Kovacs & Julesz, 1993).”

“It is known that for humans, contours close to the fovea are more easy to integrate [20–22] than in the periphery, whereas the ideal model is translationally invariant and thus unaffected by the placement of a contour.”

“However, Hess and Dakin (1997) have recently shown that contour linking is impaired in peripheral vision: this finding is particularly relevant since contour integration is generally thought to involve second-order combination of filter outputs.”

“Similarly, Hess & Dakin [34] found that contour inte gration mechanisms degrade markedly in the periphery, beyond what would be predicted by a decline in acuity or contrast sensitivity alone.”

“that it is tuned for the SF of elements [28,29] and is much cruder in the peripheral visual field, apparently relying on the output of large spatial filters [30].”

“Stimuli in the HSF block were the same as the LSF block, except that the entire stimulus was scaled to one third the retinal size (e.g., so that Gabors had a peak SF of 12 c/d) similar to prior studies (Hess & Dakin, 1997).”

“Hess and Dakin ( 1997 ), for example, suggested that contour linking is completely missing outside 10° eccentricity.”

“Recently we have confirmed that (for foveal presentation at least) this paradigm does indeed probe grouping operations combining multiple filter outputs (Hess & Dakin, 1997).”

“Most of these illusions are based on the perception of imaginary contours, an ability which apparently decreases with lateral viewing [18].”

“It has been suggested that the extended path defined by aligned Gabor elements is not detected by a single neural filter ( Hess & Dakin, 1997 ).”

“The reason for this was to keep stimulus eccentricity constant, since both receptive Weld size and the strength of lateral interactions among contours are known to vary with eccentricity (Hess & Dakin, 1997; Hess & Dakin, 1999; Nugent, Keswani, Woods, & Peli, 2003).”

“For example, contour integration has been found to be weaker in human peripheral vision (Hess and Dakin 1997), and convexity of illusory contours are harder to discriminate in the upper hemifield compared to the lower hemifield (Rubin et al.”

“Modulating spatial frequency via viewing distance does not affect contour integration performance in healthy human adults for spatial frequencies ranging from 3 to 24 cycles/deg (Hess and Dakin, 1997).”

“Hess and Dakin (1997, 1999) implemented a filter-overlap model that linked filter responses within individual orientation channels.”

“On the other hand, the regularities in the present data lead to a simpler explanation, but one different from that argued to underpin the results from contour detection studies where collinearity has been shown to be the critical feature (Field et al., 1993; Hess & Dakin, 1997).”

“Scaling was achieved by shrinking the stimulus display and increasing the viewing distance from 87.6 cm to 181.5 cm. Modulating spatial frequency via viewing distance imposes little effect on contour integration from 3 to 24 cycles/deg (Hess & Dakin, 1997).”

“…fovea is specialized for processing such properties as phase relationships (e.g., Rentschler & Treutwein, 1985) or integrating extended contours (Hess & Dakin, 1997), but such claims are frequently countered by evidence that performance in any task de- grades gradually with eccentricity…”

“As an adverse consequence, these behaviorally important objects are given a suboptimal processing in the peripheral vision (Berkley, Kitterle, & Watkins, 1975; Hess & Dakin, 1997; Kitterle, 1986; Poirier & Gurnsey, 2005; Westheimer, 1982).”

“These include association field mechanisms (e.g., Field et al., 1993), Delaunay triangulation (e.g., Watt et al., in press), and algorithms based on spatial overlap of filter responses (e.g., Hess & Dakin, 1997).”

“For example, they reduce contrast threshold for a single target bar (Polat & Sagi, 1993, 1994) and enhance detection of contours embedded in background noise (Field, Hayes, & Hess, 1993; Hess & Dakin, 1997; Li & Gilbert, 2002).”

“…spaced, or when they differ greatly in orientation or phase, means that it is unlikely that contours are detected by conventional receptive fields (Hess & Dakin, 1997); instead the results suggest that the responses of local units are grouped/ integrated in order to signal the presence of a…”

“Indeed, Hess and Dakin (1997, 1999) showed that contour integration in the peripheral visual field is limited in a manner that suggests it could be relying on the output of large receptive fields.”

“, similarity in results across variations in stimulus size) has been previously demonstrated for the CI task (Hess and Dakin, 1997; Keane et al., 2014).”

“[79] reported that contour linking due to long-range horizontal interactions is absent in the visual periphery.”

“Finally, they demonstrated that the contour-linking effect held for a circular configuration of Ternus elements, but was attenuated at increased eccentricity , concurring with previous evidence that contour linking is strongest in central vision (Hess & Dakin, 1997).”

“An instance of spatial-form perception is the detection of a string of collinear texture elements embedded in a sea of randomly oriented elements (Field, Hayes, & Hess, 1993) as this analysis is mediated by linking the outputs from local mechanisms (Hess & Dakin, 1997).”

“…known to influence contour detection are contour curvature, length, eccentricity, spatial scale and phase alignment of contour elements (Hess and Dakin, 1997; Dakin and Hess, 1998; Beaudot and Mullen, 2001, 2003; Hess et al., 2003; Ledgeway et al., 2005; Kuai and Yu, 2006), as well as…”

“The present study supports the view that contours with a smaller curvature are easier to detect than contours with a larger curvature (Field, Hayes, & Hess, 1993; Geisler et al., 2001; Hess & Dakin, 1997; Ledgeway, Hess, & Geisler, 2005).”

“This ‘linking’ of information is a critical intermediate stage in the perception of visual form [3] and has lead to the notion of an ‘association field’ [4,5] that integrates information from neighbouring filters tuned to similar orientations (see Field and Hayes [6] and Hess and Field [7] for reviews).”

“The position of the contour was jittered up to 2 around the center of the screen so that its elements appeared in different spots but at roughly the same radius so as to minimize positional uncertainty (e.g., Hess & Dakin, 1997, 1999).”

“Using the contour detection paradigm with dynamic stimuli (Field, Hayes, & Hess, 1993; Hess & Dakin, 1997), these studies have shown that orientation signals aligned with small curvatures are integrated more quickly than those with large curvatures.”

“In this paradigm, contour detection must involve global integration since it operates over spatial distances and across spatial phase in a manner that could not be achieved by conventional V1 neurons (Hess & Dakin, 1997).”

“Flavell and Draguns (1957) reviewed early work examining the initial formation or microgenesis of percepts which suggests that the global aspects of an image are available prior to the finer details (Hughes 1986; Hughes et al 1996; Lamb and Yund 1996; Navon 1977; Watt 1987). In tandem with this goes evidence on the pr…”

“Initially, it was thought that contour integration was greatly impoverished in peripheral vision beyond 10° of visual angle (Hess & Dakin, 1997; Nugent, Keswani, Woods, & Peli, 2003), but later evidence suggests that closed contours in shapes of circles and ellipses can be detected and…”