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Paul E. Dux, Troy A. W. Visser, Stephanie C. Goodhew, Ottmar V. Lipp; Delayed reentrant processing impairs visual awareness: An object substitution masking study. Journal of Vision 2010;10(7):296. doi: 10.1167/10.7.296.
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© ARVO (1962-2015); The Authors (2016-present)
In object substitution masking (OSM) a sparse, common-onsetting, mask impairs conscious target perception if it temporally trails the target and spatial attention is dispersed. Di Lollo et al.'s (2000) Reentrant Processing Model explains OSM as reflecting the interaction of feedforward and feedback processes in the brain. Specifically, upon presentation of a target and mask a coarsely coded representation of both stimuli progresses from V1 to anterior brain regions (feedforward sweep). Due to the low resolution of this information feedback/reentrant processing is employed to confirm the identity of the visual stimulation. According to this model, dispersing spatial attention delays feedforward processing, increasing the likelihood that only the mask remains visible once reentrant processing is initiated. Therefore, the mask will substitute the target in consciousness. Notably, the Reentrant Processing framework predicts that OSM will be elicited when either feedforward or feedback processing is delayed/impaired as both will increase the probability that only the mask remains visible once reentrant analysis begins. Thus, it should be possible to observe OSM for spatially attended stimuli if feedback processing from anterior regions is delayed. We presented subjects with a standard OSM paradigm (Landolt C target, four-dot mask) while they performed a difficult arithmetic task known to engage brain areas involved in reentrant processing (prefrontal and parietal cortex). All stimuli appeared in the same spatial location and, employing a standard dual-task protocol, the arithmetic and OSM tasks had either a short (100ms) or long (800ms) stimulus onset asynchrony (SOA). Increased OSM was observed at the short relative to the long SOA and this was more pronounced when subjects performed, rather than ignored, the arithmetic task. The results support a key prediction of Di Lollo et al.'s Reentrant Processing Model: if feedback processing is delayed then OSM can be observed for spatially attended objects.
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