Change detection and saccades: replicating and extending the work of John Grimes

More than seven decades of research provide evidence that participants miss surprisinglysalient changes to visual scenes. One of the most striking displays of change blindness is shownin the work of John Grimes (1996), which demonstrated that if items in an image are altered atthe exact moment a participant moves their eyes, changes often go unnoticed. However, little isknown about participants’ awareness of changes in this task, and surprisingly, the work itself hasnever been replicated. Here, we replicate and extend the work of John Grimes. Using a new setof stimuli, we conducted two experiments in two separate laboratories (the University of Floridaand Lingnan University in Hong Kong) to facilitate “simultaneous replication” of thisphenomenon. In our first experiment, we replicated the work of John Grimes and showed thatparticipants miss retroactively obvious changes to visual scenes on approximately half of thetrials. Additionally, on “miss” trials when an (unnoticed) change occurred, participants wereapproximately equally likely to select awareness of either the pre-change or post-change featurein the image. Fixation position played a critical role in modulating awareness in the task: failingto refixate changed items after the change occurred significantly increased the miss rate. Further,on miss trials, not looking at the changed item made it more likely to report awareness of the prechange item, but fixating the item after the change increased the likelihood of selecting the postchange attribute. In our second experiment, we ran the same task using image pairs where thechanges were meaningful or incongruent. Images with either a meaning change or scenecongruence change were noticed at higher rates than neutral changes, and the higher the degreeof meaning or congruence-related change, the more likely a change was detected. Together, theseresults replicate the work of John Grimes, reveal gaze-contingent correlates of change detectionin our tasks, and can inform current theories (e.g., Higher-Order Theory) of visual awareness.