Abstract
Many recent studies have revealed that, without attention, people may not perceive objects (“inattentional blindness” or IB). The studies show that IB is robust, and can occur even when the unnoticed stimuli are sustained over time and in real-world settings. In the present study, we tested whether IB would occur for a compelling multimodal stimulus. Participants viewed a video of a scene, and were given a monitoring task to create inattention. The unattended stimulus was a person scratching her nails on a chalkboard. There seems to be something inherently noxious about this stimulus, and some authors have suggested that it may be due to inharmonicities present in the sound (e.g. Halpern, Blake, & Hillenbrand, 1986). Of the participants who viewed the scene, 55 percent claimed not to have seen or heard the person scratching the board when specifically asked about it. We also tested whether the unnoticed stimulus would affect ratings of the chalkboard screech sound presented in isolation. After viewing the scene, participants were asked to rate the valence of a number of sounds, including the same chalkboard screech heard in the video. Those who did not notice the chalkboard-scratching stimulus in the video rated the screech sound as more unpleasant than did participants in the baseline condition who had not seen the video. Our research suggests that a multimodal stimulus that is very salient can be ignored, and also may influence valence ratings for the stimulus.