Discrimination between solid objects (experiment 1).

<p>(a) trained stimulus: ball; alternative stimuli: cube, cylinder, raised cylinder. (b) trained stimulus: cube; alternative stimuli: ball, cuboid, raised cuboid. In each case, dark bars indicate the bees proportion of choices for the trained stimulus, light bars indicate the proportion of choices for the respective alternative. Stimuli were tested pair-wise, asterisks denote significant discrimination (<i>t</i>-test), error bars indicate standard error of the mean; n is the total number of decisions made in each experiment, respectively.</p>