RATS EATING EYEBALLS MANUAL

There is growing evidence that animals are capable of experiencing and expressing different emotions or affective states, including those of positive valence, such as happiness or pleasure. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Ĭompeting interests: The authors have declared that no competing interests exist. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.ĭata Availability: All relevant data are within the paper and its Supporting Information files.įunding: This study was funded by the Swiss National Science Foundation (Project n. Received: MaAccepted: OctoPublished: November 30, 2016Ĭopyright: © 2016 Finlayson et al.

PLoS ONE 11(11):Įditor: Edna Hillmann, Eidgenossische Technische Hochschule Zurich, SWITZERLAND

Furthermore, 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.Ĭitation: Finlayson K, Lampe JF, Hintze S, Würbel H, Melotti L (2016) Facial Indicators of Positive Emotions in Rats. 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. 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 Grimace Scale, did not show differences between treatments. The main findings were that Ear Colour became significantly pinker and Ear Angle was wider (ears more relaxed) in the Positive Treatment compared to the Contrast Treatment. 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.

RATS EATING EYEBALLS MANUAL

The Positive 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. Adolescent 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.

Thus, this study aimed to investigate if facial expressions indicative of positive emotional state are exhibited in rats. In rodents, specific facial expressions have been found to occur in situations thought to induce negatively valenced emotional states (e.g., pain, aggression and fear), but none have yet been identified for positive states. Until recently, research in animal welfare science has mainly focused on negative experiences like pain and suffering, often neglecting the importance of assessing and promoting positive experiences.

Rats eating eyeballs