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Cited by 146Neurotransmitter Receptor Influence on BehaviorDecision-Making and Behavioral EconomicsOptimism, Hope, and Well-being

Laughing rats are optimistic.

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Rygula, Rafal, Pluta, Helena, Popik, Piotr·2012·PLoS ONE
DOI 10.1371/journal.pone.0051959PMC PMC3530570
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Abstract

Emotions can bias human decisions- for example depressed or anxious people tend to make pessimistic judgements while those in positive affective states are often more optimistic. Several studies have reported that affect contingent judgement biases can also be produced in animals. The animals, however, cannot self-report; therefore, the valence of their emotions, to date, could only be assumed. Here we present the results of an experiment where the affect-contingent judgement bias has been produced by objectively measured positive emotions. We trained rats in operant Skinner boxes to press one lever in response to one tone to receive a food reward and to press another lever in response to a different tone to avoid punishment by electric foot shock. After attaining a stable level of discrimination performance, the animals were subjected to either handling or playful, experimenter-administered manual stimulation - tickling. This procedure has been confirmed to induce a positive affective state in rats, and the 50-kHz ultrasonic vocalisations (rat laughter) emitted by animals in response to tickling have been postulated to index positive emotions akin to human joy. During the tickling and handling sessions, the numbers of emitted high-frequency 50-kHz calls were scored. Immediately after tickling or handling, the animals were tested for their responses to a tone of intermediate frequency, and the pattern of their responses to this ambiguous cue was taken as an indicator of the animals' optimism. Our findings indicate that tickling induced positive emotions which are directly indexed in rats by laughter, can make animals more optimistic. We demonstrate for the first time a link between the directly measured positive affective state and decision making under uncertainty in an animal model. We also introduce innovative tandem-approach for studying emotional-cognitive interplay in animals, which may be of great value for understanding the emotional-cognitive changes associated with mood disorders.

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  • Other evidence supports a relationship between naturally occurring variation in response to tickling measured as USV production and welfare outcomes, such as affective states.

    “Other evidence supporting a relationship between this naturally occurring variation in response to tickling measured as USV production and welfare outcomes, such as affective states, can be found in work from Rygula et al. (2012) and Mällo et al., (2007, 2009).”

    From Stage 2 Registered Report: Refinement of tickling protocols to improve positive animal welfare in laboratory rats (2025) · cites this paper as Rygula et al. (2012)

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References 37 · Cited by 146

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Authors
Rygula, R., Pluta, H., & Popik, P.
Affiliations
  • Maj Institute of Pharmacology (PL)
  • Jagiellonian University (PL)
ORCID
Popik, Piotr
Venue
PLoS ONE
Publisher
Public Library of Science (PLoS)
Published
2012-12-26
Volume
7
Issue
12
Pages
e51959
ISSN
1932-6203 (ISSN-L)
DOI
10.1371/journal.pone.0051959
PMC
PMC3530570
OpenAlex
W2051384019
Cited by
146
References
37
Citations by year
2026: 13 · 2025: 8 · 2024: 4 · 2023: 7 · 2022: 6 · 2021: 12 · 2020: 10 · 2019: 12 · 2018: 12 · 2017: 15 · 2016: 15 · 2015: 12 · 2014: 15 · 2013: 5
FWCI
4.22
Type
journal article
Language
en
Open access
Licence
Locations
  • PLoS ONE (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • Jagiellonian University Repository (Jagiellonian University) (submittedVersion, cc-by-nc-nd)
  • RePEc: Research Papers in Economics (submittedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
Funders
  • Fundacja na rzecz Nauki Polskiej (2007-2013)
  • European Regional Development Fund (2007 – 2013)
Topics
  • Life Sciences › Neuroscience › Cellular and Molecular Neuroscience › Neurotransmitter Receptor Influence on Behavior
  • Social Sciences › Decision Sciences › General Decision Sciences › Decision-Making and Behavioral Economics
  • Social Sciences › Psychology › Applied Psychology › Optimism, Hope, and Well-being
Keywords
optimism, positive affect, 50-kHz ultrasonic vocalizations, tickling, emotional valence, decision making under uncertainty, mood disorders
MeSH terms
Animals, Behavior, Animal, Cues, Discrimination Learning, Emotions, Humans, Laughter, Male, Physical Stimulation, Touch, Ultrasonics, Vocalization, Animal, Rats, Sprague-Dawley, Rats

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