Fast, slow and sudden reductions in fear. 
An experiment was carried out on 30 spider-fearful and 30 snake-fearful subjects in an attempt to replicate the finding of a correlation between the rapid reduction of fear and the reduced likelihood of significant fear returning after an interval (low return of fear).  It was also hoped to observe and closely examine the occurrence of sudden and enduring reductions in fear.  The results from the two groups of fearful subjects were reassuringly similar.  The fears of both groups were significantly reduced in a relatively brief session, and small but significant returns of fear were observed after a 2 week interval, with the slow responders reporting a higher return of fear than fast responders.  The time taken to reduce the fear correlated 0.36 with the return of fear.  A minority of subjects did experience a subjectively important, abrupt change in their fears, these 'glass-jar' experiences were associated with faster (overall) reductions in fear, a lower return of fear, and subjective estimates of permanent and generalized reductions of the fear.