Fear decrement to anxiety hierarchy items—Effects of stimulus intensity

The effects of hierarchy item intensity and duration of presentation on intra-item fear decrement were assessed with regard to systematic desensitization. Forty-eight color slides of snakes were scaled and ranked for anxiety value with the psychophysical technique of magnitude estimation by 30 female snake phobics using two response methods: verbal report and a non-verbal report instrument, the hand dynamometer. Seven test slides, spanning the scale range, were shown for 257 sec to 42 additional subjects who rated their fear level on 10 separate occasions using the hand dynamometer and verbal report. For all slides significant fear decrement occurred as a function of duration and the fear decrement across time was greater for slides of higher intensity. Negative exponential functions with similar slopes were found to fit the data for each of the slides, indicating that for each slide the same percentage of the total amount of fear decrement was lost per unit of time. The implications of these results and techniques are discussed for desensitization theory, research and therapeutic procedure.