---
type: source
id: diel-2022-uv-meta
title: A Meta-analysis of the Uncanny Valley's Independent and Dependent Variables
authors:
- Alexander Diel
- Sarah Weigelt
- Karl F. MacDorman
year: 2022
venue: ACM Transactions on Human-Robot Interaction
volume: 11(1)
pages: Article 1
doi: 10.1145/3470742
peer_review: peer-reviewed-journal
evidence_tier: A
design: 'Meta-analysis: 72 of 468 screened studies; 247 effect sizes; moderator analysis by stimulus-creation technique and measure'
modality:
- robot
- cg-face
- android
stimuli: 10 stimulus-creation techniques; 39 affect measures; 14 indirect measures
n_participants: null
n_note: 72 studies, 247 effect sizes; published online 2021
topics:
- uncanny-valley
- meta-analysis
- mechanisms
- measurement
summary: Across 72 studies the uncanny valley effect was large (Hedges' g = 1.01); face distortion produced the largest effect (g = 1.46), followed by distinct entities, realism rendering and morphing.
results:
- metric: Overall effect
  value: Hedges' g = 1.01 [0.80, 1.22]
  note: 247 effect sizes
  source_location: abstract
- metric: Face distortion
  value: g = 1.46 [0.69, 2.24]
  note: largest
  source_location: abstract
- metric: Distinct entities
  value: g = 1.20 [1.02, 1.38]
  note: ''
  source_location: abstract
- metric: Realism render
  value: g = 0.99 [0.62, 1.36]
  note: ''
  source_location: abstract
- metric: Morphing
  value: g = 0.94 [0.64, 1.24]
  note: ''
  source_location: abstract
- metric: Largest-effect affect measures
  value: threatening, likable, aesthetics, familiarity, eeriness
  note: ''
  source_location: abstract
- metric: Largest-effect indirect measures
  value: dislike frequency, categorization RT, like frequency, avoidance, viewing duration
  note: ''
  source_location: abstract
moderators:
- Stimulus-creation technique; outcome measure
limitations:
- No consensus on theoretical basis or methodology (authors)
- Heterogeneous stimuli
mechanism_supported:
- atypicality
- perceptual-mismatch
verification:
  status: verified-abstract
  confidence: high
  checked: 2026-10-07
  via: Semantic Scholar API abstract
url: null
pmid: null
pmcid: null
arxiv_id: null
openalex_id: null
oa_url: null
cited_in:
- MR-0002
updated: '2026-10-07'
---

# A Meta-analysis of the Uncanny Valley's Independent and Dependent Variables

> **Source record** `diel-2022-uv-meta` · 2022 · ACM Transactions on Human-Robot Interaction  
> **Evidence tier:** A (peer-reviewed-journal) · **Verification:** verified-abstract (compiler confidence: high)  
> **Bottom line:** Across 72 studies the uncanny valley effect was large (Hedges' g = 1.01); face distortion produced the largest effect (g = 1.46), followed by distinct entities, realism rendering and morphing.

## Citation {#citation}

Alexander Diel, Sarah Weigelt, Karl F. MacDorman (2022). A Meta-analysis of the Uncanny Valley's Independent and Dependent Variables. *ACM Transactions on Human-Robot Interaction*, 11(1), Article 1. https://doi.org/10.1145/3470742

Verification entry (identifiers, resolvers, claims with source locations): [/data/citations.json#diel-2022-uv-meta](/data/citations.json#diel-2022-uv-meta)

## Study design {#design}

| Field | Value |
|---|---|
| Design | Meta-analysis: 72 of 468 screened studies; 247 effect sizes; moderator analysis by stimulus-creation technique and measure |
| Modality | robot, cg-face, android |
| Stimuli | 10 stimulus-creation techniques; 39 affect measures; 14 indirect measures |
| Participants (N) | not recorded |
| N detail | 72 studies, 247 effect sizes; published online 2021 |
| Topics | uncanny-valley, meta-analysis, mechanisms, measurement |

## Results {#results}

| Metric | Value | Note |
|---|---|---|
| Overall effect | Hedges' g = 1.01 [0.80, 1.22] | 247 effect sizes |
| Face distortion | g = 1.46 [0.69, 2.24] | largest |
| Distinct entities | g = 1.20 [1.02, 1.38] |  |
| Realism render | g = 0.99 [0.62, 1.36] |  |
| Morphing | g = 0.94 [0.64, 1.24] |  |
| Largest-effect affect measures | threatening, likable, aesthetics, familiarity, eeriness |  |
| Largest-effect indirect measures | dislike frequency, categorization RT, like frequency, avoidance, viewing duration |  |

## Moderators {#moderators}

- Stimulus-creation technique; outcome measure

## Mechanism relevance {#mechanism}

`atypicality`, `perceptual-mismatch`

## Limitations {#limitations}

- No consensus on theoretical basis or methodology (authors)
- Heterogeneous stimuli

## Cited in {#cited-in}

- [MR-0002](/metareports/uncanny-valley-and-synthetic-faces.md): The Uncanny Valley and Synthetic Media: Does It Exist, What Causes It, and Have Deepfakes Crossed It?

## Verification {#verification}

| Field | Value |
|---|---|
| Status | `verified-abstract` |
| Compiler confidence | high |
| Checked on | 2026-10-07 |
| Via | Semantic Scholar API abstract |

Values on this page have not all been checked against the full text. Confirm them against the primary source before high-stakes use.