Extracampine vs Functional vs Reflex Hallucination
Extracampine Hallucination Functional Hallucination Reflex Hallucination
Overview
All three are special sub-types of hallucination defined by their relationship to a real sensory stimulus, rather than by their content. An extracampine hallucination needs no real stimulus at all, just an impossible location; a functional hallucination needs a real stimulus in the same sense to set it off; a reflex hallucination needs a real stimulus, but the hallucination appears in a completely different sense.
| Dimension | extracampine-hallucination | functional-hallucination | reflex-hallucination |
|---|---|---|---|
| Is a real stimulus required? | No — it can occur with no external trigger at all | Yes — a real stimulus in the same sensory channel is required to set it off | Yes — a real stimulus in one sense is required to trigger it |
| What defines the hallucination | Its physically impossible location, outside the normal range of the relevant sense organ | Occurring together with, not instead of, the real perception that triggers it | Appearing in an entirely different sense from the one the triggering stimulus was in |
| Relationship between real and hallucinated perception | Not applicable — no real stimulus is involved | Simultaneous and in the same channel — the real sound continues to be heard normally at the same time as the hallucinated voice | Cross-channel — the real stimulus and the hallucination occur in two different senses entirely |
| Sensory channel of the hallucination relative to the trigger | Same sense as usual for that hallucination, just impossibly located in space | Same sense as the triggering stimulus | Different sense from the triggering stimulus |
| Typical example | A patient hears a voice originating from many miles away, or sees something happening behind their own head | The sound of running water reliably triggers a hallucinated voice, with the real sound of the water still heard normally throughout | A real sound reliably triggers a hallucinated visual image or bodily sensation, rather than another sound |
Common confusion
Students often try to sort special hallucination types by their content, when all three are actually defined purely by their relationship to a real stimulus. The reliable approach is to ask, in order: is there a real trigger at all (ruling extracampine in or out), and if so, does the hallucination occur in the same sense as the trigger and alongside it (functional) or in a different sense entirely (reflex)?
Clarifying questions
- Does this happen out of nowhere, or is there always something real that seems to set it off?
- When it happens, do you still hear or see the real thing normally at the same time, or does the hallucination replace it, or appear in a completely different sense altogether?
- Is the hallucination coming from somewhere that would be physically impossible to actually perceive from, like far outside your field of vision or from many miles away?
Provenance
Class B · tier T1 · lifecycle migrated_candidate
- Casey, P. & Kelly, B. (2019). Fish's Clinical Psychopathology, 4th ed. Ch. 3, 'Disorders of Perception'.