As unpredictable as the content of the LSD reaction is its intensity and individual responses to the same dosage level vary considerably. The degree of sensitivity or resistance to LSD seems to depend on complicated psychological factors rather than on variables of a constitutional, biological, or metabolic nature. Subjects who in everyday life manifest a strong need to maintain full self-control, and have difficulties relaxing and "letting go," can sometimes resist relatively high dosages of LSD (300-500 micrograms) and show no detectable change. Occasionally, individuals can resist considerable doses of LSD if they have set this as a task for themselves. They may do it to defy the Therapist and compete with him or her, to prove or demonstrate their psychological "strength," to endure more than their fellow patients, to impress their friends, or for many other reasons. However, it is obvious that deeper and more relevant unconscious motives should be looked for being such superficial rationalizations. Additional causes of high resistance to the effect of the drug may be insufficient preparation, instruction and reassurance of the subject, lack of their dull agreement and cooperation, or absence of trust in the therapeutic relationship. In this case, the LSD reaction sometimes does not take its full course until the motives for resistance are analyzed and understood. Similar factors seem to be responsible for the inability of many persons to surrender to the effect of the drug under the circumstances of unsupervised self-experimentation in the presence of strangers and in unfamiliar environments. Such sessions are conducive to incomplete resolution and integration, adverse after-effects, and later recurrences ("flashbacks"). Instant sobering, which can occur at any period of the session and on any dosage level, typically indicates a sudden mobilization of defenses against impending emergence of unpleasant traumatic material.
Amongst psychiatric patients, severe obsessive-compulsive neurotics are particularly resistant to the effect of LSD. It has been a common observation in my research that such patients can frequently resist dosages of more than 500 micrograms of LSD and show only slight signs of physical or psychological distress. In extreme cases it can take several dozen high-dose LSD sessions before tghe psychological resistance of these individuals are reduced to a level where they start having episodes of regression to childhood and become aware of the unconscious material that had to be worked through. After observing several situations in which even a drastic increase of dosage - in one instance to 15000 micrograms given intramuscularly - did not result in a fully developed LSD experience, it became obvious that high psychological resistance to LSD cannot be overcome just by an increase in dosage; it has to be gradually reduced in a series of sessions. There seems to be a saturation point of LSD somewhere between 400 and 500 micrograms; if the subject does not respond adequately to this dosage, additional LSD will not change anything in the situation
There is some evidence, of an anecdotal rather than experimental nature, suggesting that a lowered response to LSD can occur in spiritually highly-developed individuals who have extensive experience of unusual states of mind or live in such a state most of the time. The most famous example of this is Ram Dass' account, according to which his Indian guru did not respond on two occasions to extremely high dosages of LSD (900 and 1200 micrograms respectively). (83)This would indicate the possibility that lack of reaction to the drug can be associated paradoxically with two opposite conditions, namely excessive rigidity and a strong psychological defense system or extreme openness and a lack of separating barriers.