Facial Indicators of Positive Emotions in Rats.

Finlayson, Kathryn; Lampe, Jessica Frances; Hintze, Sara Anna Elisabet; Würbel, Hanno; Melotti, Luca (2016). Facial Indicators of Positive Emotions in Rats. PLoS ONE, 11(11), e0166446. Public Library of Science 10.1371/journal.pone.0166446

[img]
Preview
Text
2016-Finlayson et al..pdf - Published Version
Available under License Creative Commons: Attribution (CC-BY).

Download (1MB) | Preview

Until recently, research in animal welfare science has mainly focused on negative experi- ences like pain and suffering, often neglecting the importance of assessing and promoting positive experiences. In rodents, specific facial expressions have been found to occur in sit- uations thought to induce negatively valenced emotional states (e.g., pain, aggression and fear), but none have yet been identified for positive states. Thus, this study aimed to investi- gate if facial expressions indicative of positive emotional state are exhibited in rats. Adoles- cent male Lister Hooded rats (Rattus norvegicus, N = 15) were individually subjected to a Positive and a mildly aversive Contrast Treatment over two consecutive days in order to induce contrasting emotional states and to detect differences in facial expression. The Posi- tive Treatment consisted of playful manual tickling administered by the experimenter, while the Contrast Treatment consisted of exposure to a novel test room with intermittent bursts of white noise. The number of positive ultrasonic vocalisations was greater in the Positive Treatment compared to the Contrast Treatment, indicating the experience of differentially valenced states in the two treatments. The main findings were that Ear Colour became sig- nificantly pinker and Ear Angle was wider (ears more relaxed) in the Positive Treatment compared to the Contrast Treatment. All other quantitative and qualitative measures of facial expression, which included Eyeball height to width Ratio, Eyebrow height to width Ratio, Eyebrow Angle, visibility of the Nictitating Membrane, and the established Rat Gri- mace Scale, did not show differences between treatments. This study contributes to the exploration of positive emotional states, and thus good welfare, in rats as it identified the first facial indicators of positive emotions following a positive heterospecific play treatment. Fur- thermore, it provides improvements to the photography technique and image analysis for the detection of fine differences in facial expression, and also adds to the refinement of the tickling procedure. Introduction

Item Type:

Journal Article (Original Article)

Division/Institute:

05 Veterinary Medicine > Department of Clinical Research and Veterinary Public Health (DCR-VPH) > Veterinary Public Health Institute > Animal Welfare Division
05 Veterinary Medicine > Department of Clinical Research and Veterinary Public Health (DCR-VPH)

UniBE Contributor:

Finlayson, Kathryn; Lampe, Jessica Frances; Hintze, Sara Anna Elisabet; Würbel, Hanno and Melotti, Luca

ISSN:

1932-6203

Publisher:

Public Library of Science

Language:

English

Submitter:

Jeremy Davidson Bailoo

Date Deposited:

12 Dec 2016 16:25

Last Modified:

12 Dec 2016 16:25

Publisher DOI:

10.1371/journal.pone.0166446

PubMed ID:

27902721

BORIS DOI:

10.7892/boris.90963

URI:

https://boris.unibe.ch/id/eprint/90963

Actions (login required)

Edit item Edit item
Provide Feedback