Different Signal Enhancement Pathways of Attention and Consciousness Underlie Perception in Humans

Abstract

Itis not yet known whether attention and consciousness operate through similar or largely different mechanisms. Visual processing mechanisms are routinely characterized by measuring contrast response functions (CRFs). In this report, behavioral CRFs were obtained in humans (both males and females) by measuring afterimage durations over the entire range of inducer stimulus contrasts to reveal visual mechanisms behind attention and consciousness. Deviations relative to the standard CRF, i.e., gain functions, describe the strength of signal enhancement, which were assessed for both changes due to attentional task and conscious perception. It was found that attention displayed a response-gain function, whereas consciousness displayed a contrast-gain function. Through model comparisons, which only included contrast-gain modulations, both contrast-gain and response-gain effects can be explained with a two-level normalization model, in which consciousness affects only the first level and attention affects only the second level. These results demonstrate that attention and consciousness can effectively show different gain functions because they operate through different signal enhancement mechanisms.

Conscious access in the near absence of attention: Critical extensions on the dual-task paradigm

“…This result was achieved despite minimal training and conforms with subjective reports and inferences from the dual-task literature in suggesting the phenomenological distinction of features such as face-gender might be independent from selective attention (Braun & Julesz, 1998;Koch & Tsuchiya, 2007;F. F. Li et al, 2002;Reddy et al, 2004;Tsuchiya & Koch, 2016;van Boxtel, 2017;van Boxtel et al, 2010) . Using the methods we present here, future studies might explore a range of stimulus types and features to reveal many categories of conscious perception in the near absence of attention.…”

“…One feature of this debate that has risen to prominence in recent years concerns the necessity of top-down attentional amplification for conscious perception (the necessity claim ) (Cohen, Dennett, & Kanwisher, 2016;Dehaene, 2014;Jennings, 2015) . While several noteworthy theories of consciousness remain divided on this claim, scientific enquiry has made progress in its attempts to independently manipulate top-down attention and visual consciousness using a variety of tasks and visual illusions (Tsuchiya & Koch, 2016;van Boxtel, 2017;van Boxtel, Tsuchiya, & Koch, 2010) .…”

Modelling the Effects of Ongoing Alpha Activity on Visual Perception: The Oscillation-Based Probability of Response

“…A change in alpha activity modulates the psychometric function and determines a horizontal shift that can be calculated with a numerical simulation expressed by (6), (7) and (3). When alpha increases, the psychometric function is shifted rightwards, resulting in a worsening of visual performance, as shown by the blue trace in In the literature on visual perception, a shift of the function is commonly described in terms of a contrast gain mechanism, arising from a divisive scaling of the input (Chaumon and Busch, 2014;Ling and Carrasco, 2006;Pestilli et al, 2007;Reynolds et al, 2000;van Boxtel, 2017). Interestingly, a contrast gain-like mechanism has been more associated with single-neuron activity than on the activity of the system as a whole (Kim et al, 2007), in line with the OPR.…”

The SSVEP tracks attention, not consciousness, during perceptual filling-in

“…Notwithstanding new methodological developments (Maier & Tsuchiya, 2020;Smout & Mattingley, 2018;Watanabe et al, 2011;Webb, Igelström, Schurger, & Graziano, 2016), there is still an unmet empirical need for experimental paradigms which can address this question (Pitts, Lutsyshyna, & Hillyard, 2018;Tallon-Baudry, 2011;van Boxtel, 2017;van Boxtel & Tsuchiya, 2014;van Boxtel et al, 2010a).…”