A common contrast pooling rule for suppression within and between the eyes

Abstract

Recent work has revealed multiple pathways for cross-orientation suppression in cat and human vision. In particular, ipsiocular and interocular pathways appear to assert their influence before binocular summation in human but have different (1) spatial tuning, (2) temporal dependencies, and (3) adaptation after-effects. Here we use mask components that fall outside the excitatory passband of the detecting mechanism to investigate the rules for pooling multiple mask components within these pathways. We measured psychophysical contrast masking functions for vertical 1 cycle/ deg sine-wave gratings in the presence of left or right oblique (645 deg) 3 cycles/deg mask gratings with contrast C%, or a plaid made from their sum, where each component (i) had contrast 0.5C i %. Masks and targets were presented to two eyes (binocular), one eye (monoptic), or different eyes (dichoptic). Binocular-masking functions superimposed when plotted against C, but in the monoptic and dichoptic conditions, the grating produced slightly more suppression than the plaid when C i $ 16%. We tested contrast gain control models involving two types of contrast combination on the denominator: (1) spatial pooling of the mask after a local nonlinearity (to calculate either root mean square contrast or energy) and (2) ''linear suppression' ' (Holmes & Meese, 2004, Journal of Vision 4, 1080-1089), involving the linear sum of the mask component contrasts. Monoptic and dichoptic masking were typically better fit by the spatial pooling models, but binocular masking was not: it demanded strict linear summation of the Michelson contrast across mask orientation. Another scheme, in which suppressive pooling followed compressive contrast responses to the mask components (e.g., oriented cortical cells), was ruled out by all of our data. We conclude that the different processes that underlie monoptic and dichoptic masking use the same type of contrast pooling within their respective suppressive fields, but the effects do not sum to predict the binocular case.

A Reevaluation of Achromatic Spatio-Temporal Vision: Nonoriented Filters are Monocular, They Adapt, and Can be Used for Decision Making at High Flicker Speeds

“…Orientation-tuned cortical cells are thought to inhibit each other (Morrone et al 1982; Bonds 1989; Heeger 1992), producing cross-orientation suppression, and this could be the basis for the cross-orientation masking described above (Foley 1994; Meese and Holmes 2007, 2010; Cass et al 2009). A similar outcome might be achieved by the isotropic inhibitory neurons found by Hirsch et al (2003) in layer 4 of the primary visual cortex (Meese et al 2008; Roeber et al 2008). This general type of arrangement—involving suppressive interactions—is sometimes referred to as ‘cross-channel’ masking.…”

“…This general type of arrangement—involving suppressive interactions—is sometimes referred to as ‘cross-channel’ masking. There is also good psychophysical support for this model from a dual-masking paradigm (Ross et al 1993; Foley 1994; Holmes and Meese 2004), from contrast matching (Meese and Hess 2004), from experiments involving fine-pattern discriminations (Olzak and Thomas 1999), and from the analysis of the slope of the psychometric function (Meese and Holmes 2007; Meese et al 2008). See Meese and Holmes (2007, 2010) for details and reviews.…”

Orientation bandwidths are invariant across spatiotemporal frequency after isotropic components are removed

“…It is conceivable, therefore, that this particular value may strongly favor masking mechanisms that receive equivalent input from each eye or alternatively, may elicit an equivalent response from otherwise independent contrast response functions. It is also possible that the dichoptic masking effects we observe may be driven by suppressive interactions, common to both monoptic and dichoptic processes, that occur prior to binocular combination (Meese, Challinor,&Summers, 2008), possibly precortical in origin. Again, future research is required to determine the relationship between the orientation-tuned and untuned interocular masking effects observed here and the various monocular, dichoptic, and binocular contrast gain control models (Maehara&Goryo, 2005; Meese, Georgeson, & Baker, 2006).…”

Contrast summation across eyes and space is revealed along the entire dipper function by a "Swiss cheese" stimulus

“…Another form of contrast summation is that which takes place between the eyes, usually referred to as binocular summation. Binocular summation of contrast at threshold can be substantial (a factor of 1.7; Baker, Meese, Mansouri, & Hess, 2007;Baker, Meese, & Summers, 2007;Meese, Challinor, & Summers, 2008;Meese, Georgeson, & Baker, 2006;Meese & Summers, 2009;Rose, 1980;Simmons, 2005). Certainly, it can be significantly greater than the factor of ¾2 (3 dB) predicted by models of the ideal observer (Campbell & Green, 1965) and quadratic summation (Legge, 1984;see Meese & Summers, 2009) implying that performance-limiting noise is placed beyond binocular summation.…”