The effects of viewing distance on fear of snakes.

Phobic subjects made magnitude estimations of the intensity of fear felt when viewing a snake at distances from 2.5 to 15.0 ft. Heart rate, skin conductance, and respiration were also measured throughout each 20 sec viewing period. A control group of nonphobic subjects made magnitude estimates of perceived nearness for the empty Plexiglas snake box at the same test distances. Judged fear was inversely proportional to distance. Thus, the fear-distance relation obeys Stevens' psychophysical power law with an exponent of -1.0. Examination of previous studies reporting such a finding revealed systematic departures from a power relation similar in form to the results of the perceived nearness control group, and to the expected outcome when category judgements of fear are made instead of magnitude estimates. The physiological measures varied in outcome. Measures of respiration showed no reliable effects. But heart rate and skin conductance decreased significantly for phobics as viewing distance increased.