Overview
- Published October 20 in Frontiers in Psychology, the University of Vienna-led study tested guppies and ring doves with a food-based version of the Ebbinghaus illusion.
- Researchers used miniature circular fish flakes for guppies and bowls of millet for doves as the central stimuli surrounded by larger or smaller circles.
- Guppies chose the flake ringed by smaller circles more than 70% of the time across 16 trials with 19 fish, indicating robust susceptibility to the illusion.
- Among 38 ring doves, no group-level effect emerged, with pronounced individual variation ranging from human-like responses to the opposite pattern or none.
- The team plans follow-up tests with an additional cohort of 23 doves raised together to assess environmental influences, as outside experts caution the results are preliminary and drawn from modest, uneven samples.