ArticleScientific reports2019
Welfare-improving enrichments greatly reduce hens' startle responses, despite little change in judgment bias.
Article in Scientific reports, 2019. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 10 papers.
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Who cites it
10 citing papers in PubMed, 34 citations in OpenAlex.
- A functional framework for a comprehensive study of welfare in fishes.Proceedings. Biological sciences · 2025Review
- Review
- Raising laying hens: housing complexity and genetic strain affect startle reflex amplitude and behavioural response to fear-inducing stimuli.Royal Society open science · 2024Article
- Trait sensitivity to stress and cognitive bias processes in fish: A brief overview.Personality neuroscience · 2024Review
- Social-pair judgment bias testing in slow-growing broiler chickens raised in low- or high-complexity environments.Scientific reports · 2023Article
- Affective trajectories: Are hens influenced by positive and negative changes in their living conditions?Applied animal behaviour science · 2023Article
- Enhancing their quality of life: environmental enrichment for poultry.Poultry science · 2023Article
- Use of cognitive bias as a welfare tool in poultry.Journal of animal science · 2020Review
- Quantifying defence cascade responses as indicators of pig affect and welfare using computer vision methods.Scientific reports · 2020Article
- Towards a comparative science of emotion: Affect and consciousness in humans and animals.Neuroscience and biobehavioral reviews · 2020Review
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Authors and funding
5 authors at 1 institution in 1 country.
Funding
No grant is acknowledged in the PubMed record.
Abstract
Responses to ambiguous and aversive stimuli (e.g. via tests of judgment bias and measures of startle amplitude) can indicate mammals' affective states. We hypothesised that such findings generalize to birds, and that these two responses co-vary (since both involve stimulus evaluation). To validate startle reflexes (involuntary responses to sudden aversive stimuli) and responses in a judgment bias task as indicators of avian affective state, we differentially housed hens with or without preferred enrichments assumed to improve mood (in a crossover design). To control for personality, we first measured hens' baseline exploration levels. To infer judgment bias, control and enriched hens were trained to discriminate between white and dark grey cues (associated with reward and punishment, respectively), and then probed with intermediate shades of grey. For startle reflexes, forceplates assessed responses to a light flash. Judgment bias was only partially validated: Exploratory hens showed more 'optimism' when enriched, but Non-exploratory hens did not. Across all birds, however, startle amplitudes were dramatically reduced by enrichment (albeit more strongly in Exploratory subjects): the first evidence that avian startle is affectively modulated. Startle and judgment biases did not co-vary, suggesting different underlying mechanisms. Of the two measures, startle reflexes thus seem most sensitive to avian affective state.
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