@article{Object-Substitution:4899,
      recid = {4899},
      author = {Lange, Ryan Matthew},
      title = {Feature-Level Effects in Object-Substitution Masking of  Color and Tilt},
      publisher = {University of Chicago},
      school = {Ph.D.},
      address = {2022-08},
      pages = {146},
      abstract = {Visual perception requires the construction of “neural  representations,” patterns of neuronal activity that  represent the things we see. The most well-understood  component of this construction is the feedforward  hierarchical processing pathway, in which neural signals,  starting at the eyes, are serially processed to form more  integrated and specific representations at successive  levels of the visual hierarchy. There is, however, growing  evidence that feedback signals from higher to lower levels  of the visual hierarchy moderate the quality of neural  representations, and may even dictate whether those  representations can be perceived.Object-substitution  masking (OSM) is a visual “masking” technique used to  investigate how neural representations become available to  conscious awareness. It is thought to disrupt “reentrant  processing,” a form of feedback signaling thought to be  required for visual awareness. By disrupting this reentrant  processing, OSM is thought to prevent confirmation and  conscious awareness of the initial neural representations  of briefly presented stimuli. Theories of OSM have  traditionally appealed to disruptions of “object-level”  neural representations; however, there is evidence for  “feature-level” effects in OSM, along with theoretical  grounds for predicting that reentrant processing may  operate on both object-level and feature-level neural  representations.
The experiments of this dissertation were  performed to test for and investigate feature-level  contributions to OSM for the features of tilt, color, and  lightness. Stimuli were designed to selectively activate  specific types of feature-processing neurons, and  parameterized to isolate feature-level contributions to  OSM. Experiments 1A-1C established OSM for tilt and color,  and showed that masking of these two features can be  dissociated. Experiments 2A-2D confirmed this masking using  single-feature report. These experiments did not show any  effects of similarity between targets and their masking  flankers on masking, regardless of whether that similarity  was of a task-relevant or a task-irrelevant feature.  
Finally, Experiments 3A-3C showed masking of targets  defined by a single color or luminance feature. These  experiments also showed evidence that the color or  luminance axis and identity of the target and flankers  affected degree of masking, with greater masking of and by  some types of targets and flankers than others. This  pattern of results is not as would be predicted by previous  models of the role of flanker-target similarity in OSM.  Instead, they are consistent with a feature-level  contribution to OSM that is mediated by neurons that  process specific feature signals, such as cone-opponent  L/(L+M) and S/(L+M) color signals and (L+M) luminance  signals. Furthermore, the efficacy of masking for target  color or luminance features aligns with the transmission  speeds of low-level feature-processing neurons for those  features: Specifically, color or luminance representations  processed by faster-signaling neurons are masked more  effectively than those processed by slower-signaling  neurons. From these patterns of results, a new model of OSM  is developed. This new model suggests feature-level  contributions to OSM based on relative signal-transmission  speeds of low-level feature-processing pathways for those  features.},
      url = {http://knowledge.uchicago.edu/record/4899},
      doi = {https://doi.org/10.6082/uchicago.4899},
}