Conscious access and complexity of visual features: How parallel processing of natural images interacts at different stages of computations

In a series of studies, we use different variations of the rapid serial visual presentation paradigm (RSVP) to investigate why different semantic categories have been shown to access working memory preferentially and how concurrent processing of visual targets interacts when presented in close succession. Two common findings in RSVPs with multiple targets are the Attentional Blink (AB) and Repetition Blindness (RB). Using a combination of fMRI, EEG, cognitive models of reaction time, and recent developments in computer vision to model the visual hierarchy, we extend previous findings and provide a detailed description of the mechanisms underlying target-target interaction in RSVPs. In particular, we show that targets interact at multiple levels of processing, and depending on where the interaction occurs, the effects on performance can be opposite. We show that a typical RB is observed when targets share a multivariate representational space in high-level visual domains (associated with language and semantics). Because we never use repetitions of the exact same image, RB is extended beyond exact repetitions to targets that are similar in high-level processing. In contrast, we also show that low-level similarity between targets increases T2 performance, reminiscent of a priming effect. This increase in performance is due to the faster accumulation of evidence that occurs prior to working memory activation. This thesis discusses the implications of these findings for consciousness research, attentional theories, and relevance to clinical populations