Background

Despite recent advances in understanding the relationship between consciousness and visual attention, the functional scope of unconscious attentional control is still under debate. This study shows a novel masking paradigm (see Figure below for an example of a trial sequence) in which volunteers were to distinguish between varying orientations of a briefly presented, masked grating stimulus. Combining signal detection theory and subjective measures of awareness, we found that performance on unaware trials was consistent with visual selection being weighted towards repeated orientations of Gabor patches and reallocated in response to a novel unconsciously processed orientation. This was particularly present in trials in which the prior feature was strongly weighted and only if the novel feature was invisible. Thus, our results provide evidence that invisible orientation stimuli can trigger the reallocation of top-down visual selection weights.

Figure: Example of a trial sequence: A trial started with a central fixation presented for 500ms followed by a blank of same duration. Next the target grating appeared for 33.33 ms followed by the backward mask with a duration of 350ms. After the mask’s offset another 1.5 s remained for the categorization response. At the end of the trial participants were asked to rate their subjective level of awareness using the 4-point PAS. The scheme on the top left shows an example of the repeat condition: a vertical target grating in the first trial is followed by another vertical grating in the second trial. Top right shows an example for the switch condition: the left-tilted target grating is followed by a vertical in the next trial.

This repository contains the original data and analysis scripts.

Find the paper here