Threatening stimuli elicit automatic attentional orientation that is hard to inhibit. This is either due to the strong affective information (valence) of these stimuli, or their general physical features (e.g., shape). We tested whether affective or physical features play a more important role in the modulation of attentional resources when it comes to threatening stimuli. We used a visually challenging semantic vigilance task ​where participants saw a masked word and had to respond to living meaning and ignore non-living ones. Participants were divided into two groups: group 1 saw threatening affective distractors (snakes) during the task, while group 2 was presented with nonthreatening but visually similar distractors (caterpillars). Both groups completed a control condition as well, with neutral distractor (fish). During the experiment, we manipulated the distance of these distractors from the task (close, middle, far). Our results indicate that when distractors are presented close to the task, they interfere with performance. Distractors in other positions had no effect on performance. As for the question of affective valence vs. physical feature, our study could not provide a clear answer. Participants performed well when they were shown threatening and shape-similar distractors, possibly because of the arousal stimulation effect. However, the groups had significantly different performance in the neutral trials. Threatening information in both groups might have had a priming effect during the task. This resulted in better performance when threatening affective stimuli were presented, rather than shape-similar objects, as the latter might have caused uncertainty and ambiguity in the participants.