Hypnotic depth scales such as the Stanford Hypnotic Susceptibility Scale or the Harvard Group Scale aim to quantify trance intensity, but emerging neuroimaging techniques now allow researchers to observe how these depths correlate with real-time brain activity. During induced amnesia, high-depth individuals often show reduced activation in the dorsolateral prefrontal cortex and increased dissociation in the default mode network, which aligns with reduced executive monitoring and enhanced suggestibility.
Functional MRI scans reveal that those who score higher on hypnotic depth scales also demonstrate increased connectivity between anterior cingulate cortex and salience networks. These patterns suggest that deeper hypnosis involves shifting salience away from external reality toward internally constructed suggestions. Induced amnesia tasks—such as forgetting a specific number or name—often show reduced hippocampal engagement and changes in temporal lobe activity.
These findings validate traditional behavioral depth measures with biological markers. This opens possibilities for tailoring hypnotic protocols based on an individual’s neural response to suggestion. Future applications may include pre-screening with fMRI to predict hypnotic responsiveness or refining depth scales to reflect not just behavior but measurable neurophysiological states.