David Rosenhan

Aim 🎯

Can psychiatrists distinguish between “sane” and “insane” people in psychiatric hospitals?

Method 📝

1. 8 “pseudopatients” (mentally healthy people) to 12 psychiatric hospitals in the US.

2. All said they heard a single voice saying “empty,” “hollow,” “thud.”

3. Once admitted, they stopped pretending and behaved normally.

4. Their task was to get discharged by acting sane.

Findings 🔍

• All pseudopatients were admitted, most with a diagnosis of schizophrenia.

• Average stay was 19 days (range: 7–52 days).

• Normal behaviour (like writing notes) was interpreted as a sign of disorder.

• Staff often ignored patients; depersonalisation was common.

• After the study, a hospital challenged Rosenhan to send pseudopatients.

  • The hospital flagged 41 out of 193 patients as “fake.”

  • Rosenhan had actually sent zero pseudopatients.
    → Shows the system makes both false positives and false negatives.

Uncertainty 🤔

Certainty bias - someone is too confident in their first judgement and ignores evidence that suggests they might be wrong

• Once a diagnosis is made, clinicians may:

  • Interpret normal behaviour as symptomatic

  • Ignore evidence that challenges the diagnosis

• This can lead to misdiagnosis and inappropriate treatment

Power of prejudice

Ethics

• Deception: Hospital staff were not informed that pseudopatients were part of a study.

• Lack of informed consent from staff participants.

• Potential psychological harm to staff who felt exposed or embarrassed.