Sunday, November 25, 2012

The ageless face of an Aes Sedai: Science Edition

How would the brain process a truly 'ageless' face?

Moraine, an ageless Aes Sedai (source)
I am sure this question has plagued many Wheel of Time fans, but only now has an experiment been designed to test it. Just 4 days ago, Homola et al. (2012) published a paper in PLoS ONE in which they have people guess ages of people in pictures and scan their brains. 

Homola et al. (2012) Figure 1A. (Which one looks most Aes Sedai to you?)
The first interesting thing that they found was that the older the person in the picture (either a real picture of a real person, or a hybrid 'morphed' picture like the ones above), the harder it was to tell how old they were. This isn't really that surprising, as the range of ages that can 'look' a certain age gets wider over the years.

Homola et al., (2012) Figure 2B.
Here they plot the standard deviation in years for people's guesses as to the age.

The authors showed videos of the faces morphing from one age to another to volunteers while they were in the fMRI machine.

As a side note: they found that there was no difference between male and female volunteers. If they had I think a big deal would have been made about it. but since they didn't it's just a tiny sentence in a long paper.

Ok, back to the processing of age. They threw out the results from people who were really really bad at rating age because they 'weren't motivated' and weren't really trying apparently. (This could be a bit of cherry picking or data massaging) Then they compared the areas of the brain that were active for people who were really really good at guessing age, and people who were only average.

Homola et al., (2012) Figure 4D

The basic finding was that the posterior angular gyrus area (pANG) in the left hemisphere was 5 times more active for the expert age guessers than it was for average. Conclusion: pANG is important for age-processing. This on its own is good to know, but not amazingly interesting. What I think is cool is the idea that the authors present as a  follow up experiment in their discussion:

"Even though our study highlights pANG as one key component for age processing, its precise role in this context is still speculative and needs further investigation. Our model, illustrated in Figure 7, gives rise to interesting hypotheses: One testable prediction would be that disruption of left pANG activity using transcranial magnetic stimulation (TMS), for example, should impair numerical age but not gender judgements, and that brain lesion-symptom mapping can eventually dissociate the two. " Homola et al., (2012)
So now we know, the Aes Sedai must have some magic that transcranially impairs pANG in everyone around them so they can't guess their age. That is how to stay truly ageless.

© TheCellularScale
Homola GA, Jbabdi S, Beckmann CF, & Bartsch AJ (2012). A Brain Network Processing the Age of Faces PLoS One DOI: 10.1371

1 comment:

  1. They're using a Glamor! LOL.

    What an awesome adventure that was! I'm going to be keeping an eye out for the new incarnation of Robert Jordan...just to see what other cool stories we can pump out of him when he grows up.