If Carr had only talked about the Internet and digital technology as distractions, his book might still be interesting, but not very significant. It's no great insight to realize that texting while driving is stupid, or that responding to every Tweet and clicking on every link will keep you from getting anything done.
Carr marshals a good deal of evidence drawn from recent, and not so recent experimental work, which shows, he believes, that the use of digital technology is actually changing not just what we do, but how we think.
He refers us to the work of Patricia Greenfield, a UCLA development psychologist who studies the use of media and its effect on learning: "Every medium develops some cognitive skills at the expense of others. Our growing use of screen-based media, she said, has strengthened visual-spatial intelligence, which can improve the ability to do jobs that involve keeping track of lots of simultaneous signals, like air traffic control. But that has been accompanied by new weaknesses in higher-order cognitive processes, including abstract vocabulary, mindfulness, reflection, inductive problem solving, critical thinking, and imagination."
Or as Carr puts it: "We're becoming, in a word, shallower."
Experts Disagree On Carr's Thesis
To be sure, there is experimental work that points in a different direction. In a rather unfriendly piece in the New York Times Book Review last month, Jonah Lehrer cited a different set of experts from UCLA who "found that performing Google searches led to increased activity in the [brain], at least when compared with reading a book-like text."
Lehrer, a contributing editor at Wired, then went on to contradict Carr's major thesis, saying: "Interestingly, this brain area underlies the precise talents, like selective attention and deliberate analysis, that Carr says have vanished in the age of the Internet. Google, in other words, isn't making us stupid -- it's exercising the very mental muscles that make us smarter."
But does it?
Carr argues that our brains are "plastic," that is they are modified by the tasks we undertake. "When we're constantly distracted and interrupted, as we tend to be online, our brains are unable to forge the strong and expansive neural connections that give depth and distinctiveness to our thinking. We become mere signal-processing units, quickly shepherding disjointed bits of information into and then out of short-term memory."
Even the use of links that give readers access to useful information not in the text has a downside, Carr believes. Erping Zhu, a researcher at the University of Michigan, tested reading comprehension by having people read the same online article, but she varied the number of links included in the passage. She then tested the subjects, and found that comprehension declined as the number of links increased. Readers were forced to devote more and more of their attention and brain power to evaluating the links and deciding whether to click on them
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