Effects of a cold-water stressor on psychomotor and cognitive functioning in humans.

The effects of an acute stressful and painful stimulus, cold water, on psychomotor and cognitive functioning, was assessed in 14 healthy volunteers. Subjects immersed their forearm in ice-cold water (2-3 degrees C) and luke-warm water (37 degrees C) for 3 min, and during this time period a psychomotor or cognitive test was performed. These immersions were done over the course of two experimental sessions, spaced at least 2 days apart, with six trials in each session. Within each session, cold and warm water immersions alternated. Results indicated that flicker-from-fusion threshold from the critical flicker frequency test was higher in the cold-water condition than in the luke-warm-water condition, indicative of increased alertness from the cold stimulus. Short-term memory was attenuated, however, in the cold-water condition. Performance on other tests including those that required speed and/or concentration were not affected by the manipulation. Subjects rated the cold-water stimulus as painful and bothersome, and their blood pressure was significantly elevated by the stimulus. We conclude that a painful stimulus may affect psychomotor and/or cognitive functioning, but the relationship is somewhat complex and depends on the particular tests used.