The reasoning
Phenomenology is the disciplined characterisation of an experience's form (independent of content). Form discriminates; content rarely does. "I hear voices" is inert until you establish:
- Locus: external space vs inside the head (true hallucination vs pseudohallucination).
- Person: second‑person ("you are worthless" — affective) vs third‑person running commentary / voices arguing (classically first‑rank, schizophrenia‑spectrum).
- Modality: auditory (functional psychosis), visual/olfactory/tactile → raise the probability of an organic or substance cause.
- Relation to sleep: hypnagogic/hypnopompic experiences are near‑normal.
- Insight and control, distress, and command content (a risk item).
High‑yield discriminators
- Illusion vs hallucination: illusion = misperception of a real stimulus; hallucination = percept with no stimulus.
- Obsession vs delusion: obsession is ego‑dystonic, resisted, recognised as one's own (OCD); delusion is held with conviction as external reality.
- Pseudohallucination: experienced in inner subjective space, insight relatively retained — softens the case for a primary psychosis.
- Modality as a triage signal: isolated visual hallucinations (esp. with clouding/fluctuation) → delirium, substance withdrawal, occipital/temporal pathology; olfactory → temporal lobe epilepsy/tumour; tactile (formication) → stimulant/cocaine, alcohol withdrawal. These are probabilistic pointers, not proofs.
The documentation standard
Replace "visual hallucinations" with "reports seeing small animals at the foot of the bed, worse at night, in the context of 3 days' reduced alcohol intake and tremor" — that single line practically writes the differential (withdrawal/DTs) for you.
Pitfalls
- Recording modality/label without form → the note can't discriminate later.
- Forgetting that new visual/olfactory/tactile hallucinations are 'organic until proven otherwise.'
Pearls
- 🎯 Form over content. How the experience is structured out‑discriminates what it's about.
- 🩺 Always ask the safety phenomenology: command hallucinations, and whether the patient feels compelled to act.
Next → Apply this to the single richest phenomenological field — thought (Concept 6).