Abstract
In the past decade, studies have claimed that the gist of a scene is immune from inattentional blindness (IB) (Mack and Rock, 1998) and can be perceived without focused attention (Li et al., 2002; Rousselet et al., 2002). However, it seems possible that these studies did not use sufficiently difficult primary tasks and that more demanding tasks would show that gist perception requires attention. To test this possibility, we devised a novel form of the IB paradigm in which we employed the multiple object tracking task (MOT) and had participants track 4 of 8 identical black circles. While tracking these circles, a sequence of background images were rapidly presented (one every 65ms), consisting of grids of squares comprised of randomized colors. On the fifth trial, the second to last background image was unexpectedly a natural scene from one of five categories (beach, mountain, indoor, highway, city). Of the 10 subjects run, all showed inattentional blindness to the scene, failing to report its presence. Immediately following these 5 trials, participants completed 20 trials where they switched the focus of their attention from the tracking task to monitoring the background. When this was done, these same participants could correctly identify when a scene was present and classify that scene with 92% accuracy. In Experiment 2, participants tried to track objects and detect a scene simultaneously. While tracking 4 objects, participants' tracking and scene detection performance dropped significantly relative to when they completed each task individually (p <.05 for both tasks). However, when the tracking load was lessened to 3 objects, performance did not decrease (p > .51 and p > .37 respectively). Together, these two experiments show that contrary to what has been previously claimed, gist perception is not immune from inattentional blindness and requires attention.