The new study, which measured starlings ability to recognize new songs, showed that learning a second task could undermine performance of a previously learned task.
For the study, the researchers did two experiments using 24 starlings each.
They played two recorded songs from other starlings and tested the birds ability to recognize and repeat the two songs. After learning to recognize the two songs, the birds were later trained to recognize and perform a different pair of songs.
The researchers examined the effect of sleep on the consolidation of starlings memories in the experiment. After learning the second pair of songs, they were tested on the first before they went to sleep. They varied the time between testing.
Researchers found that regardless of the time between the daytime testing periods, learning the second pair of songs interfered with the birds ability to remember the first pair.
Learning the first pair of songs also interfered with the birds ability to remember the second pair when they were tested on the second pair before they went to sleep.
When the starlings were allowed to sleep, however, they showed increases in performance on both the first and second pair of songs, suggesting that sleep consolidation enhances their memory, overcoming the effects of interference UChicago News reported.
When taught a new song pair after awaking, the birds were still able to remember what they had learned on the previous day, despite the new interference.
The research has been published in Psychological Science.