title: Collective enhancement of numerical acuity by meritocratic leadership in fish.
abstract: It has been known for more than a century that interacting people can generally achieve more accurate decisions than single individuals. Here we show that interacting guppy fish (Poecilia reticulata) achieve a superior level of numerosity discrimination well beyond the average ability of the isolated individual fish. This enhancement of numerical acuity was observed in dyadic interactions when (Experiment 1) the dyad chose which larger shoal of guppies to join and when (Experiment 2) the dyad chose the higher or the lower numerosity among two decision options after having learned the task individually. Dyadic accuracy and that of the more competent member of each dyad matched closely, supporting the hypothesis that meritocratic leadership arises spontaneously between dyadically interacting fish, rather than the 'many wrongs' principle that has been used to explain group superiority in many species.
authors.affiliation: 1] University of Padova, Department of General Psychology, Padova, Italy [2] University of Padova, Centro di Neuroscienze Cognitive, Padova, Italy.
authors.forename: Angelo
authors.initials: A
authors.lastname: Bisazza
authors.affiliation: 1] University College of London, Institute of Cognitive Neuroscience, UK [2] IRCCS Ospedale San Camillo, Venice, Italy [3] University of Melbourne, Psychological Sciences, Australia.
authors.forename: Brian
authors.initials: B
authors.lastname: Butterworth
authors.affiliation: University of Padova, Department of General Psychology, Padova, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Piffer
authors.affiliation: University College of London, Institute of Cognitive Neuroscience, UK.
authors.forename: Bahador
authors.initials: B
authors.lastname: Bahrami
authors.affiliation: University of Padova, Department of General Psychology, Padova, Italy.
authors.forename: Maria Elena
authors.initials: ME
authors.lastname: Miletto Petrazzini
authors.affiliation: University of Padova, Department of General Psychology, Padova, Italy.
authors.forename: Christian
authors.initials: C
authors.lastname: Agrillo
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D005260:Female; D005399:Fishes / Q000502:physiology*; D007857:Leadership; D011036:Poecilia / Q000502:physiology*