---
title: Expectancy effects
description: "| Expectancy effects refer to the power that clients’ and therapists’ and researchers’ beliefs have on change outcomes of therapies. Includes **Placebo** and **Nocebo** effects. **Double blind randomised trials (DBRCTs)** have the great methodological power to remove such effects but…"
url: "https://www.psyctc.org/psyctc/glossary2/expectancy-effects/"
updated: "2021-11-14"
category: All OM book glossary entries
---

# Expectancy effects

| Expectancy effects refer to the power that clients’ and therapists’ and researchers’ beliefs have on change outcomes of therapies. Includes **Placebo** and **Nocebo** effects. **Double blind randomised trials (DBRCTs)** have the great methodological power to remove such effects but only when everyone: client, therapist and evauator/research can be kept blind to what therapy was given. This is quite often possible for pharmacological interventions when DBRCTs become rightly the prime efficacy evaluation but such blinding is almost never possible for psychosocial interventions like therapies and expectancy effects undoubtedly play an important part in therapies. |
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#### Try also ...

[Placebo](https://www.psyctc.org/psyctc/glossary2/placebo-effect-and-placebos/)
[Nocebo](https://www.psyctc.org/psyctc/glossary2/nocebo-effect/)
[Blinding](https://www.psyctc.org/psyctc/glossary2/blinding/)
[Randomised Controlled Trials (RCTs)](https://www.psyctc.org/psyctc/glossary2/randomised-controlled-trial-rct/)
[Double Blind Controlled Trials (DBRCTs)](https://www.psyctc.org/psyctc/glossary2/double-blind/)
Hierarchy of evidence
[NICE](https://www.psyctc.org/psyctc/2021/07/09/nice-consultation-2021/)
[Cochrane](https://www.psyctc.org/psyctc/glossary2/cochrane-collaboration-library/)
[ESTs (Empirically Supported Treatments)](https://www.psyctc.org/psyctc/glossary2/ests-empirically-supported-treatments/)

#### Chapters

Chapter 10.