The effects of an unexpected spider stimulus on skin conductance responses and eye movements: an inattentional blindness study

Are spiders evolutionarily relevant threat cues that capture attention automatically and preattentively—also in non-fearful persons? Previous studies concerning this question did not examine responses to unexpected spider stimuli, although this is an ecologically valid situation. Therefore, we conducted an inattentional blindness (IB) experiment. While unselected participants (N = 120) were focusing their attention on a visual discrimination task, suddenly a spider or a flower image appeared. The rates of reported detection were not enhanced for spider images, and fear of spiders had no moderating influence on IB rates. However, spider pictures in general elicited greater skin conductance responses than flower pictures, and this difference was also observed for pictures that were not reported afterward. Moreover, eye movement data revealed that the spider stimulus was initially fixated more often than the flower stimulus. In sum, our findings imply that enhanced reactions to unexpected spider images are independent of fear level and include early engagement processes. Awareness of a spider picture does not seem to be a prerequisite for elevated arousal.