In humans, the processing of chemosensory anxiety signals in the insula, precuneus, cingulate cortex, and in the fusiform cortex [11] has been discussed to resemble a contagion of the feeling of anxiety between the signal sender and the signal perceiver. However, the chemical communication of an extreme level of psychological and physiological stress (first time sky diving) results in a rather restricted activation of the amygdala [12]. Furthermore, in the context of chemosensory stress signals, the perceptual acuity for social safety cues is reduced [13], whereas the perceptual acuity for social cues of danger is increased [12], [14]. On a behavioral level, chemosensory stress signals of conspecifics augment defensive reflexes (startle) in humans [15], [16] and rats [17], [18]. However, the attentional capacities for the identification of sweat stimuli donated by anxious subjects appear to be limited [19], [20].
