The adorable dog in the photo is paying attention.
"Lifting the ears up straight is, in almost every species, a clue that the animal is putting some work into it. They're paying close attention, they're concentrating," says Steven Hackley, a researcher with the University of Missouri.
What about in humans? Except for a rare few, most of us are unable to move our ears in any direction at will. When we’re paying close attention we might lean in or furrow our brow, but we don’t make our ears stand up.
However, humans do seem to have some vestigial muscles around their ears, and these might be employed when we’re trying to pay close attention. Here’s how NPR’s Science section summarized it:
…people do have certain muscles around the ear that never get used, except by those people who are able to deliberately wiggle their ears as a party trick.
Recently, Hackley and some colleagues looked to see if they could record subtle electrical signals in those muscles, by putting electrodes on them.
[…] Twenty volunteers got wired up with electrodes around their ears and sat in a lab surrounded by speakers.
They were told to pay attention to a certain audiobook, which was picked to be engaging. Andreas Schroeer of Saarland University says this audiobook was full of "fun little trivia that people could actually motivate themselves to listen to."
After a little while, though, other sounds faded in, at different volumes. These were picked to be distracting podcasts. "One of them was actually about the history of podcasts," says Schroeer, who notes that people later reported how much difficulty they had in listening at different times.
As the listening task got easier and harder over the course of this experiment, the researchers saw changes in the electrical activity in the ear muscle that, in animals, perks the ear up.
a) This was an experimental design. Classify its two main variables:
|
Variable name |
Levels of this variable |
Is this manipulated or measured? |
Is the variable an IV or DV? |
For the IV: was it manipulated as independent groups or within groups? |
b) Which type of design was it: posttest only? Pretest-posttest? Repeated measures? Or concurrent measures? Explain your answer.
c) Sketch a graph of the study’s results. You don’t know the exact values but you should be able to guess the pattern (hint: Be sure to put the DV on the y-axis).
d) Given the results of this study, what would be a good experiment to run next? Why?
Suggested answers:
|
Variable name |
Levels of this variable |
Is this manipulated or measured? |
Is the variable an IV or DV? |
For the IV: was it manipulated as independent groups or within groups? |
|
Level of difficulty in hearing the audiobook |
No difficulty (no distraction), some difficulty, (a quiet distraction) most difficulty (a louder distraction) |
Manipulated |
IV |
Within groups |
|
Degree of activity in ear-raising muscles |
Low to high |
Measured |
DV |
n/a |
b) It is a repeated- measures design because the IV was within-groups and the DV (level of activity in the ear muscles) was measured repeatedly across different IV levels.
c) Possible results pattern:
You can check your sketch (and mine) against the published results, which are open-access in Frontiers in Neuroscience.
d) Your answers may vary, but if you read the full story, you can see what other researchers were saying about the study, and perhaps get some ideas for future research there.