Expectation creates something out of nothing: The role of attention in iconic memory reconsidered.

Conscious experience depends on attention and expectation, but some argue it can occur without attention. Experiments on iconic memory (IM) are often cited as evidence for attention-independent consciousness. A prior study found that when attention is diverted from an IM letter display, people fail to notice missing letters. This work replicates and extends that finding by measuring subjective visibility and testing post-cue effects. Results show that participants who do not realize letters are absent perceive illusory letters, indicating phenomenal consciousness persists even without attention. Expectation generates illusory content that overwrites valid IM content, suggesting this experimental paradigm cannot reliably assess iconic memory content.

Study at a glance

Abstract

Conscious experience is modulated by attention and expectation, yet is believed to be independent of attention. The experiments on iconic memory (IM) are usually taken as support for this claim. However, a recent experiment demonstrated that when attention is diverted away from the IM letter display subjects fail to see the absence of IM letters. Here we contribute to the ongoing debate by overcoming experimental shortcomings of this previous experiment, by measuring subjective visibility and by testing the effect of the post-cue. We were able to replicate these earlier findings and extend them by demonstrating that subjects who do not realize the absence of letters perceive illusory letters. This result means that there is still phenomenal consciousness, even when attention is diverted. Expectation creates illusory content that overwrites valid IM content. Taken together these findings suggest that the present experimental paradigm is not appropriate to make claims about IM content.