Material & Methods


Four animals, housed at Furuviksparken, Gävle, participated in the experiments. The group housed at Furuviksparken are a family-group, where Kariakou and Lisha are the parents of Engelbrekt and Anita.

The four white-faced sakis housed at Furuviksparken, Gävle, Sweden. Top (left to right): Kariakou (intact male), Lisha (female). Bottom (left to right): Engelbrekt (castrated male), Anita (female).


A two bottle preference test of short duration was employed. Here, the animals were allowed two minutes to drink from two drinking bottles, and the weight of the bottles were measured before and after each trial. Additionally, between each meal and each trial the animals were given atleast 30 minutes of rest to ensure that the animal’s preference for any of the solutions was not influenced by the taste of food remnants or the taste of solutions used in previous trials.

10 trials/concentration of an acid were performed, and about 6 trials per individual per day were conducted.

Anita during one of the trials.

The acids tested were citric acid, ascorbic acid, malic acid, tannic acid and acetic acid. The acids were tested in the same order for all individuals. Additionally, the position of the bottles were pseduo-randomised for each trial to avoid position biases. Further, testing followed a pseudo-randomised order of presumably more or less attractive concentrations to ensure cooperation from the animals.

Two experiments were conducted: a taste preference threshold experiment and a sour taste tolerance experiment.

In both experiments, one bottle always contained a 50 mM sucrose solution.

For the taste preference threshold experiment, the other bottle contained 50 mM of sucrose + a defined concentration of an acid.

For the sour-taste tolerance experiment, the other bottle contained 400-10 mM of sucrose + 10, 30 or 50 mM of citric acid.

Now, are you ready for some Results?