Wednesday, June 22, 2005
Study finds... not.
Who's gonna talk you home tonight?
NUMBERS JOCKS. Practically every day, some news organization or other presents us with a dire headline that includes the phrase "Study finds." Without a full exploration of the content, each of these can function as a factless propaganda item that reinforces an existing belief or annoys us by contradicting an existing belief. The interesting question is whether we, as individuals, behave differently depending on which of these two circumstances applies. Today, I came across this teaser in Drudge:
STUDY: Cellphones take up driver attention...
I happen to believe that this is true. It seems reasonable to think that there would be fewer accidents if all those businesspeople, housewives, and teenagers weren't motoring down the highway yakking on the phone. On the other hand, my libertarian inclinations resist the notion that the cops should have yet another excuse to punish people for what they do on their own private property (i.e., in our cars) before any external driving misconduct occurs. So I was curious to see what the "study" had found. The opening paragraphs certainly sounded authoritative:
Using a cellphone -- even with a hands-free device -- may distract drivers because the brain cannot handle both tasks, U.S. researchers said on Tuesday.
Imaging tests show the brain directs its
resources to either visual input or auditory input, but cannot fully
activate both at the same time, the team at Johns Hopkins University in
Johns-Hopkins. They're smart. They must know. But then Reuters
briefly describes the methodology:
Writing in the Journal of Neuroscience, Yantis and colleagues said they tested people aged 19 to 35 by showing them a computer display while they wore headphones playing voices.
At the same time, the volunteers brains were scanned using functional magnetic resonance imaging.
They were told to look for specific
numbers, for instance, on a computer screen, while hearing recorded
voices saying a stream of numbers...
This, the article concludes, "is like driving and trying to talk on
Uh, no, it isn't. It may be that there is some fundamental validity
to the point that driving and talking on the phone are competing tasks
which the brain doesn't handle efficiently at the same time, but this
test proves no such thing. It's a setup. The exercise performed by the
volunteers involved identifying the exact same information, specific
numbers, via two different senses, sight and hearing. The one task is a
direct and highly specific confusion factor for the other. What kid
hasn't teased a pal who was trying to memorize a phone number from the
yellow pages by reciting a stream of random numbers out loud? In this
case, it's obvious the brain will switch its number processing capacity
from one input source to the other, aware that no mixed attention span
can do justice to either input.
This is very far from being akin to the circumstance of driving and
talking on a cellphone. Neither task is directly analogous to the
processing of numbers, which occurs in a different part of the brain
from language processing. If you doubt this, consider the difference
between the number task -- identifying specific numbers -- and the
phone conversation task, which can lose or ignore plenty of specific
words and still achieve understanding of the gist. And the brain
process that attends to the road is neither numeric nor linguistic --
it's performing a kind of subconscious pattern recognition, looking for
important exceptions in the overall visual field which require the
application of conscious decision making. If it were otherwise, we
would find it impossible to do what we all do on a regular basis: drive
some familiar route with hardly any recollection of the trip after
we've reached our destination. No exceptions spotted, no conscious
The study focuses on one kind of processing function, not related to
driving or talking, and tries to compare it to a situation that
involves two altogether different kinds of processing functions which
may or may not create complications in an organ well known to be
capable of advanced multiprocessing tasks.
The conclusions are nonsense. Johns-Hopkins should know better, and
we should all be reminded of the need to be skeptical when we're urged
to be credulous of some scientific authority and even when we're
inclined to agree with the conclusions being reported.
Is this how the link between global warming and human behavior came
to be regarded and reported as a "fact"?