Binomial assessment of behavioral-phenotypic variations: constancy of choices, trial effects, and social interaction effects in mass-screened color preferences of quail chicks (Coturnix coturnix japonica).

Individual variations in repeated approach choices between colors by quail chicks were efficiently and reliably identified by methods of binary mass screening and binomial assessment. Choices between a pair of identical white stimuli showed only random variations, which indicated that position habit, systematic alternation, and extraneous stimulus factors did not influence performances. Choices between blue and red colors showed significant individual variations, which were free of influences from changes in the probabilities of choices on repeated trials, interdependence between trials, and interdependence between individual performances of mass-screened subjects. Genetic determination of individual variations were shown by strong responses to bidirectional genetic selection of choices between blue and red, which also introduced small social interaction effects in mass-screened performances. Results are discussed in relation to the use of binomial distribution for identifying phenotypic units and variations in choice behaviors.