Neurological Correlates

Handedness of females in the news:

1. Left handed female humans are the quickest thinkers.

Ion N. Beratis;  Andreas Rabavilas;  George N. Papadimitriou; Charalabos Papageorgiou, “Effect of handedness on the Stroop Colour Word Task, “  Laterality: Asymmetries of Body, Brain and Cognition E-Pub: 22 July 2009 DOI: 10.1080/13576500903071104

2. Female cats, as a group, are predominantly right pawed.

D.L. Wells and S. Millsopp, “Lateralized behaviour in the domestic cat, Felis silvestris catus,” Animal Behaviour, In Press, Corrected Proof, Available online 16 July 2009, doi:10.1016/j.anbehav.2009.06.010

OK, first the quick thinking. What makes a fast thinker?

Brain laterality helps. It helps if you can access both sides of your brain quickly.

This is indirectly tested with the Stroop tasks . Basically, one’s recognition of color when reading words for colors (“blue”), and words in color (“blue“) is timed and compared. There are a number of ways to play Stroop, with numbers, emotionally-volitile words, etc. but the gist is that there are two different things going on: color recognition, and then word cognition. So if you say “Red!” when you see “blue” then you are exhibiting Stroop interference.

Who has trouble with this? People with disrupted wiring.  Multiple sclerosis, which wreaks havoc with myelin sheaths, really slows down the speed for Stroop tests.  People on top of Mt. Everest without much oxygen get slowed down.

Who’s fast? Crossword puzzle doers. See,  Neuro-movie review: Wordplay and brain hemispheres,   February 25th, 2008

Is it only processing speed?  So you see “blue” and first process the word, and then process the color, and then get to the conflict? Or is the conflict upstream?

It seems to be in both the initial stimulus as well as in the processing.  Szucs D, Soltész F, White S. ,”Motor conflict in Stroop tasks: direct evidence from single-trial electro-myography and electro-encephalography.,” Neuroimage 47:1960-73. Epub 2009 May 27 doi:10.1016/j.neuroimage.2009.05.048

The other thing about brain laterality is that it relates to handedness. It was thought that people who are left handed have a more developed (for lack of a better word) right brain, the opposite side. But this may not be the case — it may be that people who are left handed are just really fast thinkers — not preferentially right-brained or left brained. Like  Pres. Obama who is left handed.

Ion N. Beratis;  Andreas Rabavilas;  George N. Papadimitriou; Charalabos Papageorgiou, “Effect of handedness on the Stroop Colour Word Task, “  Laterality: Asymmetries of Body, Brain and Cognition E-Pub: 22 July 2009 DOI: 10.1080/13576500903071104

. . .The data suggest that handedness is associated with cognitive function alterations, which lead to a smaller Stroop interference of left-handers irrespectively of sex, an effect that is more pronounced in the female subpopulation.

The paper is notable for two reasons:

First, the lead author’s first name is “Ion”.   Ironic — Ion can’t be in a union because that would un-ion. Whoa.

Second, lefties are the fastest on the Stroop tasks, and female lefties were the fastest of all. My guess is that this is just a matter of geography — female brains are smallest, and so the sparks of neural electricity going from one side to the other just wouldn’t have as far to travel. It could be something else, like particularly conducive fatty acids in the neural wiring.

DIY Stroop Tests

Here are a bunch of Stroop tests you can try at home.

Here’s an on line one.