(IMAGE) McGill University Caption Female birds could pull strings to trigger playback of songs. On the days between tests of their song preferences, birds were administered drugs to mimic dopamine while they listened to a less-preferred song. When birds were tested again, their preferences for the less-preferred song had increased. Credit McGill University Usage Restrictions None License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.