Scientific Quantification of Positive Affect Expands to Dolphins and Parrots

The scientific community is advancing the objective quantification of positive emotions, or 'positive affect,' in non-human species, a methodological shift intended to move beyond historical reservations concerning anthropomorphism in research. This multi-university initiative, informally termed the 'joy-o-meter,' seeks to establish measurable indicators for intense pleasure across diverse animal taxa. The research framework is currently expanding its scope to include studies on dolphins, building upon foundational work previously conducted with great apes and parrots to define objective markers for happiness and well-being.

One primary focus involves the New Zealand kea parrot, native to the South Island's mountains and forests, whose behavior suggests a strong capacity for positive emotional states. Behavioral biologist Ximena Nelson from the University of Canterbury in Christchurch, New Zealand, has documented kea engaging in activities such as making snowballs and sledding down ski hut roofs, particularly in sunny, snowy weather. This natural curiosity is being formalized through experiments linking specific vocalizations and behaviors to rewards like peanut butter, which elicits a significantly stronger reaction than less preferred foods such as carrots.

Kea exhibit distinct vocalizations associated with play, notably the contagious 'warble calls' that can initiate 'tap-dancing' and general playful behavior in nearby conspecifics, mirroring the function of human laughter. This play call is notable because, unlike the common 'screech' contact call used for social cohesion, the most likely response to a warble is another warble, suggesting a direct contagious effect on mood. To objectively differentiate joy from stress, researchers are analyzing biological markers, including hormones extracted from fecal samples collected during play sessions; one experiment involving 12 parrots included one individual, Plankton, who provided sizable samples every 20 minutes.

The Templeton Foundation began funding the parrot and dolphin studies in 2024, following earlier promising results with apes. Parallel investigations are now focusing on marine mammals, specifically dolphins, to establish analogous objective markers for their positive affect. While the characteristic dolphin 'smile' is a fixed anatomical feature unrelated to emotional state, researchers are exploring vocalizations such as the 'victory squeal.' This squeal is observed when dolphins successfully catch a fish or receive a reward from trainers, suggesting a release of the reward chemical dopamine, and can occur even in the trainers' absence.

Studies on captive dolphins, including individuals named Bo and Buster, have shown that novel enrichment items, such as a three-foot-long block of ice, sometimes elicited avoidance rather than positive engagement, underscoring the difficulty in identifying universal joy triggers. The methodology relies on identifying reliable indicators—behavioral cues, vocalizations, and biological markers—that signal brief, intense pleasure following a 'windfall paradigm,' where an expected minimal reward is unexpectedly surpassed, such as a dolphin receiving six fish instead of one. The successful quantification of these positive states, which has already seen application in optimism tests for rats and poultry, promises to refine how captive and wild animal well-being is assessed and promoted globally, aligning with the broader ethical ambition of strengthening positive emotions.