Abstract
A debate regarding the discrete or continuous nature of visual awareness has revolved around the attentional blink (AB). The AB is a transient limitation in the ability to perceive the second (T2) of two masked targets 200-500ms after the attentional processing of the first target (T1). The AB is considered to represent both a central limitation of attention and limitations within earlier visual stages of information processing (Dux & Marois, 2009). Central to this debate is whether the failure to report T2 is due to the discrete failure of information reaching post-perceptual stages of processing, or whether the graded quality of information produces a weak conscious representation. Asplund et al. (2014) applied a mixture-modeling analysis (Zhang & Luck, 2008) to errors in T2 responses to estimate 1) the width of the error distribution to measure the precision of the T2 percept and 2) the probability of successful T2 encoding, assuming an all-or-none representation of T2. They found evidence in favor of discrete failures within central stages of information processing. Here, we tested whether the AB necessarily leads to discrete failures of perception, or whether weak representations can occur once attention is taxed within the same early visual processing channel (Awh et al. 2004), or feature dimension of orientation. Observers were presented with two oriented gratings, which appeared in a rapid serial visual presentation of random noise. Participants performed two task types: report the orientation of both targets, or of T2 alone. Mixture-modeling analysis revealed an AB, defined by the interaction between task and time, in precision but not in the probability of successful encoding. These results suggest that the quality of T2 representations gradually becomes more precise as attentional resources are made available over time, and that discrete or continuous processing depends on the level in which attentional capacity is taxed.
Meeting abstract presented at VSS 2015