Hyper-arousal decreases human visual thresholds.

Adam J Woods,Philip Wirtz,John W Philbeck,Jessica Witt

doi:10.1371/journal.pone.0061415

Adam J Woods, Philip Wirtz + Show 2 more

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https://doi.org/10.1371/journal.pone.0061415

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Abstract

Arousal has long been known to influence behavior and serves as an underlying component of cognition and consciousness. However, the consequences of hyper-arousal for visual perception remain unclear. The present study evaluates the impact of hyper-arousal on two aspects of visual sensitivity: visual stereoacuity and contrast thresholds. Sixty-eight participants participated in two experiments. Thirty-four participants were randomly divided into two groups in each experiment: Arousal Stimulation or Sham Control. The Arousal Stimulation group underwent a 50-second cold pressor stimulation (immersing the foot in 0–2° C water), a technique known to increase arousal. In contrast, the Sham Control group immersed their foot in room temperature water. Stereoacuity thresholds (Experiment 1) and contrast thresholds (Experiment 2) were measured before and after stimulation. The Arousal Stimulation groups demonstrated significantly lower stereoacuity and contrast thresholds following cold pressor stimulation, whereas the Sham Control groups showed no difference in thresholds. These results provide the first evidence that hyper-arousal from sensory stimulation can lower visual thresholds. Hyper-arousal's ability to decrease visual thresholds has important implications for survival, sports, and everyday life.

Highlights

Hyper-arousal is any increase in arousal above an organism’s normal awake arousal state. [3,5] Normal arousal, or normo-arousal, is the average level of arousal in an awake, nonbrain damaged organism and serves as the baseline state of responsiveness for conscious behavior. [1,2] Hyper-arousal can range from small increases due to caffeine intake or startle response to abnormally high levels associated with post-traumatic stress disorder or high-voltage electric shock. [5,12] In particular, the present study investigates whether inducing a state of hyperarousal through sensory stimulation improves the discriminability of 1) depth relationships signaled by binocular disparity and 2) contrast gratings
To determine whether non-significant differences at baseline between groups account for significant effects of Arousal Stimulation, we performed an analysis of covariance (ANCOVA) with signed difference in threshold as the dependent variable with Group and Baseline as independent factors
Planned contrasts utilizing paired-samples t-test between Baseline (mean threshold 6 standard error (SE) = 0.10260.006) and Stimulation (mean threshold 6 standard error (M6SE) = 0.08660.004) for each group demonstrated a significant effect of cold pressor stimulation (CPS) on contrast thresholds from Baseline to Stimulation for participants in the Arousal group

Summary

Introduction

Conscious sensory perception is dependent upon the coordinated activity of arousal and sensory systems in the brain. [1] Arousal serves as a substrate of consciousness that is a) important for providing a basic aptitude for behavioral response to the environment and b) a means for optimizing behavior. [2,3,4,5] Just as hypo-arousal can compromise our ability to respond to the environment (e.g., coma), hyper-arousal holds the potential to enhance our performance (e.g., fight or flight). [4,5,6,7,8,9,10,11] In most domains of vision science, arousal is not incorporated into theoretical models. Conscious sensory perception is dependent upon the coordinated activity of arousal and sensory systems in the brain. There is a pressing need to investigate the possible consequences of increased arousal for visual perception. The present study begins an investigation of the influence of hyper-arousal on perceptual judgments of visual information in the environment. Hyper-arousal is any increase in arousal above an organism’s normal awake arousal state. [3,5] Normal arousal, or normo-arousal, is the average level of arousal in an awake, nonbrain damaged organism and serves as the baseline state of responsiveness for conscious behavior. [1,2] Hyper-arousal can range from small increases due to caffeine intake or startle response to abnormally high levels associated with post-traumatic stress disorder or high-voltage electric shock. Hyper-arousal is any increase in arousal above an organism’s normal awake arousal state. [3,5] Normal arousal, or normo-arousal, is the average level of arousal in an awake, nonbrain damaged organism and serves as the baseline state of responsiveness for conscious behavior. [1,2] Hyper-arousal can range from small increases due to caffeine intake or startle response to abnormally high levels associated with post-traumatic stress disorder or high-voltage electric shock. [5,12] In particular, the present study investigates whether inducing a state of hyperarousal through sensory stimulation improves the discriminability of 1) depth relationships signaled by binocular disparity and 2) contrast gratings

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