Psychophysiological assessment and correction of spatial disorientation during simulated Orion spacecraft re-entry.

The National Aeronautics and Space Administration (NASA) has identified a potential risk of spatial disorientation, motion sickness, and degraded performance to astronauts during re-entry and landing of the proposed Orion crew vehicle. The purpose of this study was to determine if a physiological training procedure, Autogenic-Feedback Training Exercise (AFTE), can mitigate these adverse effects. Fourteen men and six women were assigned to two groups (AFTE, no-treatment Control) matched for motion sickness susceptibility and gender. All subjects received a standard rotating chair test to determine motion sickness susceptibility; three training sessions on a manual performance task; and four exposures in the rotating chair (Orion tests) simulating angular accelerations of the crew vehicle during re-entry. AFTE subjects received 2 h of training before Orion tests 2, 3, and 4. Motion sickness symptoms, task performance, and physiological measures were recorded on all subjects. Results showed that the AFTE group had significantly lower symptom scores when compared to Controls on test 2 (p = .05), test 3 (p = .03), and test 4 (p = .02). Although there were no significant group differences on task performance, trends showed that AFTE subjects were less impaired than Controls. Heart rate change scores (20 rpm minus baseline) of AFTE subjects indicated significantly less reactivity on Test 4 compared to Test 1 (10.09 versus 16.59, p = .02), while Controls did not change significantly across tests. Results of this study indicate that AFTE may be an effective countermeasure for mitigating spatial disorientation and motion sickness in astronauts.

G-loading and vibration effects on heart and respiration rates.

BACKGROUND: Operational environments expose pilots and astronauts to sustained acceleration (G loading) and whole-body vibration, alone and in combination. Separately, the physiological effects of G loading and vibration have been well studied; both have effects similar to mild exercise. The few studies of combined G loading and vibration have not reported an interaction between these factors on physiological responses. METHODS: We tested the effects of G loading (+1 and +3.8 G(x)) and vibration (0.5 gx at 8, 12, and 16 Hz), alone and in combination, on heart and respiration rate. RESULTS: We observed an effect of G loading on heart rate (average increase of 23 bpm, SD 12) and respiration rate (average increase of 5 breaths per minute, SD 5), an effect of vibration on heart rate, and an interaction on heart rate. With vibration, we observed heart rate increases of 4 bpm (SD: 3) with no increase in respiration rate. In the +1 G(x) condition, the largest heart rate increase occurred during low-frequency (8 Hz) vibration, while at +3.8 G(x), the largest heart rate increase occurred during high-frequency (16 Hz) vibration, demonstrating interaction. DISCUSSION: Consistent with previous reports, our G-loading and vibration effects are similar to mild exercise. In addition, we observed an interaction between G loading and vibration on heart rate, with maximum heart rates occurring at a higher vibration frequency at +3.8 G(x) compared to +1 G(x). The observed interaction demonstrates that G-loading and vibration effects are not independent and can only be properly assessed during combined exposure.

Cardiovascular change during encoding predicts the nonconscious mere exposure effect.

These studies examined memory encoding to determine whether the mere exposure effect could be categorized as a form of conceptual or perceptual implicit priming and, if it was not conceptual or perceptual, whether cardiovascular psychophysiology could reveal its nature. Experiment 1 examined the effects of study phase level of processing on recognition, the mere exposure effect, and word identification implicit priming. Deep relative to shallow processing improved recognition but did not influence the mere exposure effect for nonwords or word identification implicit priming for words. Experiments 2 and 3 examined the effect of study-test changes in font and orientation, respectively, on the mere exposure effect and word identification implicit priming. Different study-test font and orientation reduced word identification implicit priming but had no influence on the mere exposure effect. Experiments 4 and 5 developed and used, respectively, a cardiovascular psychophysiological implicit priming paradigm to examine whether stimulus-specific cardiovascular reactivity at study predicted the mere exposure effect at test. Blood volume pulse change at study was significantly greater for nonwords that were later preferred than for nonwords that were not preferred at test. There was no difference in blood volume pulse change for words at study that were later either identified or not identified at test. Fluency effects, at encoding or retrieval, are an unlikely explanation for these behavioral and cardiovascular findings. The relation of blood volume pulse to affect suggests that an affective process that is not conceptual or perceptual contributes to the mere exposure effect.