The effect of duration of exposure on systematic desensitization and extinction.

An important variable which has only recently received attention (Proctor, 1968; Watts, 1971) is the influence of intra-item exposure time to aversive stimuli on systematic desensitization. Long single exposure to hierarchy items was more effective in reducing avoidance behavior than short exposure (Ross and Proctor, 1973). It is possible, therefore, for duration of exposure to be a confounding variable in previous desensitization research.In studies where exposure only conditions were ineffective (Davison, 1968; Lomont and Edwards, 1967), the visualization time was less than 15 sec. Successful utilization of extinction-like procedures employed longer exposure times (Vodde and Gilner, 1971 for 20–30 sec; Crowder and Thornton, 1970 for 30 sec; Sue, 1972 for 20 sec; Nawas, Welsch and Fishman, 1970 for 60 sec: Wolpin and Raines, 1966 for up to 10 min).Intra-item exposure time may also account for the discrepant findings on the influence of cognitive variables on the efficacy of systematic desensitization. In the studies where expectations or therapeutic instructions were important (Leitenberg et al., 1969; Valins and Ray, 1967), subjects were exposed to aversive stimuli for 10–15 sec. Where positive expectations were unimportant, the exposure time was longer (McGlynn and Mapp, 1970 for 20–30 sec; McGlynn, Gaynor and Puhr, 1972 for 20–30 sec; McGlynn, Reynolds and Linder, 1971 for 20–40 sec; Lomont and Brock, 1971 for 60 sec). Therapeutic expectations, relaxation, and other variables may assume importance during periods of short exposure.So far, there has been no adequate investigation of intra-item exposure time on both extinction and desensitization. The procedures employed by Watts (1971) and Proctor (1968) do not allow such a comparison to be made. The purpose of the present study is to examine the influence of short (5 sec) and lengthy (30 sec) exposure to aversive stimuli on extinction and desensitization conditions.In line with the results of Davison (1968) and Lomont and Edwards (1967), it was predicted that exposure of short duration would be less effective than exposure of longer duration under the extinction condition (Vodde and Gilner, 1971 ; Crowder and Thronton, 1970; Nawas et al., 1970; Wolpin and Raines, 1966). No specific predictions were made on the desensitization groups. There were four experimental groups: (1) two exposure only groups (visualization for either 5 sec or 30 sec), and (2) two systematic desensitization groups (visualization for 5 sec or 30 sec). A no-treatment control group was also employed.