McPhetres, J. | bioRxiv Science

bioRxiv2023

Diverse stimuli induce piloerection and yield varied autonomic responses in humans

This research provides an in-depth exploration into the triggers and corresponding autonomic responses of piloerection, a phenomenon prevalent across various species. In non-human species, piloerection occurs in reaction to a variety of environmental changes, including social interactions and temperature shifts. However, its understanding in humans has been confined to emotional contexts. This is problematic because it reflects solely upon subjective experience rather than an objective response to the environment, and because, given our shared evolutionary paths, piloerection should function similarly in humans and other animals. We observed 1,198 piloerection episodes from eight participants while simultaneously recording multiple autonomic and body temperature indices, finding that piloerection in humans can indeed be elicited by thermal, tactile, and audio-visual stimuli. The data also revealed variations in cardiac reactivity measures: audio-visual piloerection was associated with greater sympathetic arousal, while tactile piloerection was linked to greater parasympathetic arousal. Despite prevailing notions of piloerection as a vestigial response in humans, it does respond to decreases in skin temperature and induces a rise in skin temperature during episodes. This research underscores that piloerection in humans is not solely an affective response to emotional stimuli. Rather, it is best understood as a reflexive response to environmental changes, suggesting a shared functional similarity with other species.

physiology↗

bioRxiv2023

Individuals lack the capacity to accurately detect emotional piloerection

Piloerection (e.g., goosebumps) is an essential thermoregulatory and social signalling mechanism in non-human animals. While humans also experience piloerection--often being perceived as an indicator of profound emotional experiences--its comparatively less effective role in thermoregulation and communication might influence our capacity to monitor its occurrence. We present three studies (total N = 617) demonstrating participants general inability to detect their own piloerection events and their lack of awareness that piloerection occurs with a similar frequency on multiple anatomical locations. Participants over-reported piloerection events with only 31.8% coinciding with observable piloerection, a bias unrelated to piloerection intensity, anatomical location, heart rate variability, or interoceptive awareness. We also discovered a self-report bias for the forearm, contradicting the observation that piloerection occurs with equal frequency on multiple anatomical locations. Finally, there was low correspondence between self-reports of being "emotionally moved" and observed piloerection. These counterintuitive findings not only highlight a disconnect between an obvious physiological response and our capacity for self-monitoring, but they underscore a fascinating divergence between human and non-human species. While piloerection is vital in non-human organisms, the connection between piloerection and psychological experience in humans may be less significant than previously assumed, possibly due to its diminished evolutionary relevance. Statement of ImpactThis research reveals a striking dissociation between an obvious physiological response-- piloerection--and human capacity for self-perception. While this highlights the limitations of relying on self-report measures, it also underscores an important divergence between humans and non-human species. We propose that the relation between piloerection and psychological experience in humans is less pronounced than in other species, potentially due to its diminished role in human evolution.

animal behavior and cognition↗