Summary of the dose-effect functions of feeding and learning.

<p>We divide the median values for each quinine concentration by the lowest median value found within one experiment (and multiply by −1), thus yielding the displayed normalized scores (green: Learning; red: Feeding). The half-maximal effect of QUI on feeding appears to require a concentration of QUI that is almost one order of magnitude higher than for learning. As for choice the maximal effect can for practical reasons not be determined (see Discussion), a similar display for choice would insinuate a too low concentration as “half-maximal” (see Fig. S2), and is therefore not included. The inset uses data from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0040525#pone.0040525-Niewalda1" target="_blank">[26]</a> to display the dose-effect functions of feeding and learning for sodium chloride for comparison. Please note that changing the concentration of sodium chloride in the rearing-food may alter the balance between its appetitive and aversive effects <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0040525#pone.0040525-Russell1" target="_blank">[36]</a>.