Grand averaged pupil waveforms. Grand averaged pupil waveforms following baseline correction. Shaded regions represent +/− 1 standard error. The dashed line at 0 ms represents the onset of the tone. A) Pupil response observed during the habituation phase. B) Pupil response during the acquisition phase. The threat associated cue prompts pupil dilation similar to studies that used visual cues. This is in line with research that has shown pupil dilation occurs in numerous paradigms and modalities.