This book presents an approach to quantifying consciousness and its various states. It represents over ten years of work in developing, test­ ing, and researching the use of relatively simple self-report question­ naires in the retrospective assessment of subjective or phenomenologi­ cal experience. While the simplicity of the method allows for subjective experience to be reliably and validly assessed across various short stim­ ulus conditions, the flexibility of the approach allows the cognitive psy­ chologist, consciousness researcher, and mental health professional to quantify and statistically assess the phenomenological variables associ­ ated with various stimulus conditions, altered-state induction tech­ niques, and clinical procedures. The methodology allows the