Hypervigilance involves increased attentional scanning of the environment to facilitate the detection of possible threats. Accordingly, this state is mostly bound to external attention and as a corollary, it might be detrimental to internal attention and further affect attentional balance defined as the ability to switch dynamically between these two domains. In the current study, we aimed to address this question and induced hypervigilance in 49 healthy participants through the presentation of a task-unrelated aversive sound while they performed the switching attention task (SAT), which was previously devised to study attentional balance. The skin conductance response results, as well as subjective sound ratings, confirmed that the hypervigilance manipulation was successful. At the behavioral level, hypervigilance led to a more symmetrical balance between internal and external attention compared to the control and neutral conditions, where it was asymmetrical, replicating previous studies. Moreover, using a drift diffusion model, we found that hypervigilance reduced the drift rate for internal repetition trials, suggesting that hypervigilance possibly caused an impaired shielding of internal attention.
