Animals in flow - towards the scientific study of intrinsic reward in animals

When the Job is Done: Exhaustion or Elation? A Pilot Study on the Effects of Cognitive and Physical Effort on the Behavior of Minipigs

Long-term affective states such as mood may best reflect the welfare of an animal. They are likely to depend on how the animal assesses the outcomes of its own behavioral actions. These post-consummatory states are often of low arousal and, accordingly, difficult to observe. Here, we investigated whether the behavior of minipigs shown during the hour following an experimental session differed between a cognitive and physical task. We assumed that differences would allow us to see how the animals assessed the tasks after completing them. The minipigs increased resting, feeding, and drinking behavior after the physical task compared to the cognitive task, indicating the need to make up for energy spent. In addition, foraging was reduced after the cognitive task compared with a control day, whereas non-food-related exploration remained on a similar level. This change in behavior might be interpreted as "leisure." Overall, the approach used seems promising to assess how much an animal likes the outcome of its behavior. These situations in turn cumulatively make up longer-term mood states and are, correspondingly, relevant for the long-term welfare state of animals.

Levelling up the study of animal gameplay

Play in humans and other animals is widespread and intuitive to recognise. Creative, unstructured play is difficult to quantify, but games direct play towards a specific goal and have defined rules, mechanics and rewards. To date, games have been under-utilised in human and animal behavioural neuroscience. This review evaluates evidence that animals can play human games, including game-theory contests, tangible games, and video games. Animals can be trained to play various human games with cognitive capacities such as role adoption, rule-following and performance monitoring. Animals can make irrational gameplay decisions that jeopardise rewards and have salient emotional responses to winning and losing. Games can advance the field of behavioural neuroscience in several ways. Cognitive tasks can become more engaging and ecologically relevant by adding game elements, known as gamification. Games can be used to induce and measure more naturalistic emotional responses to the process of overcoming (progression/regression) and end state (winning/losing) of cognitive challenges. There is also scope to target specific cognitive skill deficiencies in captive animals using games. However, a recent rapid increase in computerised testing environments raises an important ethical question about the boundary between games and reality for animals.

A consensus on the definition of positive animal welfare

The concept of animal welfare is evolving due to progress in our scientific understanding of animal biology and changing societal expectations. Animal welfare science has been primarily concerned with minimizing suffering, but there is growing interest in also promoting positive experiences, grouped under the term positive animal welfare (PAW). However, there are discrepancies in the use of the term PAW. An interdisciplinary group arrived at a consensus that 'PAW can be defined as the animal flourishing through the experience of predominantly positive mental states and the development of competence and resilience. PAW goes beyond ensuring good physical health and the prevention and alleviation of suffering. It encompasses animals experiencing positive mental states resulting from rewarding experiences, including having choices and opportunities to actively pursue goals and achieve desired outcomes'. The definition also considers individual and species-specific differences. It provides a framework for researchers to investigate PAW and thereby generate innovative, informative and reproducible science. Studies of PAW can contribute to a richer picture of an animal's life and may elucidate the biological foundations of happiness. The definition creates opportunities to inspire scientific progress in animal biology and to align animal care practices, legislation and markets with societal expectations.

Assessment of positive experiences using associative learning in chickens

To determine whether differences in positive experiences can influence associative learning ability, 2 tasks were conducted with 90 laying hens at the peak of the laying period. The selected hens were reared in a larger flock under the same housing conditions without perches, so they had the same rearing experiences and were moved to either enriched cages or to the floor system at 16 wk of age. They belonged to 3 breeds (Slovenian barred hen: Ba; brown hen: Br; silver hen, S), with 30 hens per breed. The predictor signal, the sound of a clicker, with a 3-second delayed reinforcer (commercial layer feed) was used to mark the desired behaviour (pecking for feed). Hens that associated feed with a clicker (85.06%) were taught 2 tasks, the colour discrimination task (CD) and the target following task (TF). In the CD, the hens had to discriminate between yellow, red and blue colors and peck at a yellow magnet only. In the TF, the desired behaviour was to follow a target, a purple ball on a stick, from 1 perch to another and peck it at the end of the perch. The main results of the hens associating the signal with feed were that the Ba hens learned faster than the S hens (P = 0.006) and required fewer clicker sounds than the Br hens in the CD (P = 0.003). Floor hens that completed CD or TF or both took less time to complete the task (CD, P = 0.03, TF, P = 0.06; both tasks, P = 0.02) or with fewer clicker sounds (CD task; P = 0.02) than cage hens. Although these results suggest that Ba hens and floor hens showed better associate learning performance, probably because they perceived their environment as more rewarding and thus potentially more positive, caution is needed in interpretation considering social experiences and that the ability to perch and the ability to move quickly on a perch can be confounded in TF and both tasks can be confounded with foraging ability.

Animal affect, welfare and the Bayesian brain

According to the Bayesian brain hypothesis, the brain can be viewed as a predictive machine, such that predictions (or expectations) affect how sensory inputs are integrated. This means that in many cases, affective responses may depend more on the subject's perception of the experience (driven by expectations built on past experiences) rather than on the situation itself. Little research to date has applied this concept to affective states in animals. The aim of this paper is to explore how the Bayesian brain hypothesis can be used to understand the affective experiences of animals and to develop a basis for novel predictions regarding animal welfare. Drawing from the literature illustrating how predictive processes are important to human well-being, and are often impaired in affective disorders, we explore whether the Bayesian brain theories may help understanding animals' affective responses and whether deficits in predictive processes may lead to previously unconsidered welfare consequences. We conclude that considering animals as predictive entities can improve our understanding of their affective responses, with implications for basic research and for how to provide animals a better life.

Review: Rethinking environmental enrichment as providing opportunities to acquire information

Environmental enrichment, that is making the environment of animals more complex, was first designed to enhance the welfare and cognitive abilities of captive animals, and was more recently applied to farm animals. Enrichments can be sensory, physical, social, occupational, feeding-based, or a mix of these, with a view to improve animals' welfare. We posit that enrichments share the common factor of providing information to animals so that enrichment is all about providing the animal with a way to acquire information by interacting with the environment. Animals enjoy acquiring information, and the process of acquiring information acts in a way that enables them to better adapt to future environments. This reframed view of enrichment has several implications including prolonging the duration of exposure to an enrichment does not necessarily increase the impact of that enrichment, neutral and even slightly negative stimuli may still be enriching, complex and variable environments are enriching, and the more intensively an animal can engage with the environment, the more it will benefit from enrichments. These implications should be further explored by comprehensive re-analyses of findings from the enrichment literature and/or by dedicated experiments.

Using caffeine as a chemical means to induce flow states

Flow is an intrinsically rewarding state characterised by positive affect and total task absorption. Because cognitive and physical performance are optimal in flow, chemical means to facilitate this state are appealing. Caffeine, a non-selective adenosine receptor antagonist, has been emphasized as a potential flow-inducer. Thus, we review the psychological and biological effects of caffeine that, conceptually, enhance flow. Caffeine may facilitate flow through various effects, including: i) upregulation of dopamine D1/D2 receptor affinity in reward-associated brain areas, leading to greater energetic arousal and 'wanting'; ii) protection of dopaminergic neurons; iii) increases in norepinephrine release and alertness, which offset sleep-deprivation and hypoarousal; iv) heightening of parasympathetic high frequency heart rate variability, resulting in improved cortical stress appraisal, v) modification of striatal endocannabinoid-CB1 receptor-signalling, leading to enhanced stress tolerance; and vi) changes in brain network activity in favour of executive function and flow. We also discuss the application of caffeine to treat attention deficit hyperactivity disorder and caveats. We hope to inspire studies assessing the use of caffeine to induce flow.

Resource choice during ontogeny enhances both the short- and longer-term welfare of laying hen pullets

We hypothesised that resource choice during early life contributes to both current and longer-term beneficial effects on animal welfare. We investigated this hypothesis in a longitudinal cross-over experiment with laying hen pullets (Gallus gallus domesticus) reared in pens with one or four litter and perch types, respectively (n = 8 pens/treatment, all providing ample and identical litter and perch space). After 4 weeks (chick period), half the pens were modified to provide the opposite treatment (juvenile period). After 11 more weeks, all groups were moved to novel, identical laying pens (adult period; Week 16-27). In support of our hypothesis, the opportunity to choose between multiple litter and perch variants was associated with higher levels of positively-valenced behaviours, including play as chicks and dustbathing as juveniles and adults, and lower levels of negatively-valenced behaviours, including feather pecking as chicks and juveniles and aggressive pecking as adults. Resource choice in the juvenile period also led to better juvenile and adult plumage condition, and greater growth as adults. We conclude that the opportunity to choose among different litter and perch types, instead of having only one type of each, had both short- and longer-term positive effects on the birds' affective states and physical condition.

The agency domain and behavioral interactions: assessing positive animal welfare using the Five Domains Model

Animal welfare denotes how an animal experiences their life. It represents the overall mental experiences of an animal and is a subjective concept that cannot be directly measured. Instead, welfare indicators are used to cautiously infer mental experiences from resource provisions, management factors, and animal-based measures. The Five Domains Model is a holistic and structured framework for collating these indicators and assessing animal welfare. Contemporary approaches to animal welfare management consider how animals can be given opportunities to have positive experiences. However, the uncertainty surrounding positive mental experiences that can be inferred has resulted in risk-averse animal welfare scientists returning to the relative safety of positivism. This has meant that aspects of positive welfare are often referred to as animal 'wants'. Agency is a concept that straddles the positivist-affective divide and represents a way forward for discussions about positive welfare. Agency is the capacity of individual animals to engage in voluntary, self-generated, and goal-directed behavior that they are motivated to perform. Discrete positive emotions are cautiously inferred from these agentic experiences based on available knowledge about the animal's motivation for engaging in the behavior. Competence-building agency can be used to evaluate the potential for positive welfare and is represented by the Behavioral Interactions domain of the Five Domains Model. In 2020, The Model was updated to, amongst other things, include consideration of human-animal interactions. The most important aspect of this update was the renaming of Domain 4 from "Behavior" to "Behavioral Interactions" and the additional detail added to allow this domain's purpose to be clearly understood to represent an animal's opportunities to exercise agency. We illustrate how the Behavioral Interactions domain of The Model can be used to assess animals' competence-building agency and positive welfare. In this article, we use the examples of sugar gliders housed in captivity and greyhounds that race to illustrate how the agentic qualities of choice, control, and challenge can be used to assess opportunities for animals to exercise agency and experience positive affective engagement.