We don't include many animal behavior studies in ERM blog, but here's a great one about animal memory. How long do you think wild animals can remember new skills they have learned? In this report in The Scientist, we read that the North Island Robin (known in the Maori language as toutouwai) of New Zealand can apparently remember a skill up to 22 months, without any reminders in the meantime. Here's how the study worked.
[Originally, scientist Rachel Shaw] demonstrated that wild toutouwai living in the Zealandia Wildlife Sanctuary in Wellington, New Zealand, are capable of learning a novel task. Using a rectangular box with three compartments, each covered by a lid that swivels to the side to reveal its contents, she incrementally taught the birds how to peck the lids aside and retrieve mealworms hidden inside two of the three wells.
(By the way, the story in The Scientist includes a photo of the experimental apparatus and a video of a bird using it.)
Roughly a year later, Shaw was giving a public talk at the sanctuary about conservation and her work with birds. As she explained the memory apparatus she had used in her previous research, a toutouwai appeared.
“I haven’t given this bird this task in over a year,” she recalls telling the audience, “so let’s see how he does.” As if on cue, the bird instantly flew down to the apparatus and started opening the lids. That got her wondering: how many of the other birds could repeat the memory task and how long could they remember what they were taught?
This serendipitous event prompted Dr. Shaw to design a study to find out. Before reading on, how would you study this question?
In the new study, Shaw and her coauthor, Annette Harvey, tested 32 of the initial 64 birds that were trained in 2015 and 2016 and banded for individual identification, 30 of which performed the memory task by spontaneously pecking the lids and opening them on their first try. None of the trained birds had seen the box between the initial training and retesting, though some of the untrained control birds had encountered the apparatus in a previous research project. The time between when the birds had first learned the lid-opening behavior and subsequent testing ranged from 10 to 22 months. By contrast, the 17 untrained birds were unable to complete the task.
The article mentions several other examples of long-term memory in animals, including pigeons, tortoises, nutcrackers, and chickadees. Read more if you are interested!
Questions
a) This study might be considered a simple observational study but it might also be classified as a quasi-experiment. What do you think?
b) What role does the untrained comparison group play in this research?
c) Do you think the effect size in this study would be considered small or large? Explain your answer.
d) Chapter 6 describes important construct validity considerations for observational studies, such as reactivity, observer bias, and observer effects. Which of these might be relevant in this study on toutouwai?
Thanks to my friend Dr. Stephen Chew for sharing this story on Twitter!
