Modality as a triage signal
- Auditory — commonest in primary psychosis. Third‑person (running commentary, voices arguing) and thought echo are phenomenologically weighted toward schizophrenia; second‑person derogatory voices fit psychotic depression.
- Visual — raise probability of organic/substance cause (delirium, withdrawal, Lewy body disease, occipital/temporal pathology, hallucinogens).
- Tactile — formication (insects crawling) → stimulant/cocaine intoxication, alcohol withdrawal.
- Olfactory/gustatory — think temporal lobe epilepsy, tumour, migraine aura.
Phenomenological refinements
- True hallucination (external space, no insight, involuntary) vs pseudohallucination (inner subjective space, insight relatively retained).
- Illusion (misperceived real stimulus) vs hallucination (no stimulus).
- Functional (triggered by a real stimulus in the same modality), reflex (cross‑modal trigger), extracampine (outside the sensory field), hypnagogic/hypnopompic (sleep transitions — near‑normal).
Turn phenomenology into risk assessment
For any voice, establish command content: what does it instruct, do you feel compelled, has it told you to harm yourself/others? Command hallucinations with low resistance + a congruent delusional framework = elevated acute risk.
Pitfalls
- Treating new visual/olfactory/tactile hallucinations as "psychiatric" — they are organic until excluded.
- Recording "auditory hallucinations" without person/locus — you lose the schizophrenia‑vs‑affective signal.
Pearls
- 🎯 Modality + form triage the cause before any diagnostic label.
- 🩺 Every voice gets a command/risk enquiry — non‑negotiable.
Next → Integrate delusions, hallucinations, form, and course into the diagnostic decision (Concept 12).