Makaela Nartker¹ (), Chaz Firestone¹, Howard Egeth¹, Ian Phillips¹; ¹Johns Hopkins University

In inattentional blindness (IB), subjects who fail to report unexpected stimuli are typically assumed not to have seen them. Recent work challenges this assumption by showing that inattentionally blind subjects can respond above-chance to stimuli they report not noticing (Nartker et al., 2022), suggesting that inattention may not completely abolish awareness. However, these results have been limited to briefly and peripherally presented static stimuli (e.g., a line appearing on the edge of a display for 200 ms). Does this pattern extend to long-lasting IB involving highly salient dynamic stimuli? Here we report data from a large-scale online study (N>10,000) addressing precisely this question. Subjects were shown a gray rectangular display containing moving white and black squares, and counted how often the white squares bounced off its perimeter (adapted from Wood & Simons, 2017). For some subjects, the third trial included an additional brightly colored and highly salient shape (a circle or triangle that was orange or green), which traversed the height of the display for five full seconds. After this critical trial, subjects were asked the standard IB question: “Did you notice anything unusual on the last trial that wasn’t there on previous trials?” (yes/no) followed by additional questions probing the extra object’s color, location and shape. By including absent trials in which no additional stimulus appeared, we found that subjects were biased to report not noticing (c=0.45, 95% CI=[0.41,0.49]), suggesting greater awareness than revealed by yes/no questioning. Consistent with this interpretation and our previous studies, inattentionally blind subjects could report the color of the unexpected object at above-chance levels (d′=0.12, 95% CI=[0.02,0.23]). Strikingly, these ‘non-noticing’ subjects were also above-chance in discriminating the objects’ shape (d′=0.23, 95% CI=[0.13,0.33]), raising the possibility that even mid- or high-level features survive inattention.

Acknowledgements: National Science Foundation BCS #2021053; JHU Catalyst Award