Boy, Susan Greenfield's argument is weak. (Check it out here, but it's basically just more of her 'modern tech scares me and it should scare you, why do I think so? Because I'm me.')
She says that doing too much of something is detrimental, which is almost a tautology, and then just reiterates this comment and her non-evidence based worries, interleaved with citing someone else's version of this comment and his non-evidence based worries. Conspicuously lacking are any facts, observable evidence, or indications of trends — and particularly disturbing is that despite this, she is continuing to garner attention for her theories.
Baroness Professor Susan Greenfield is professor of synaptic pharmacology at Gresham College, Oxford University. This recognises her specialism in the action of chemicals upon nerves, muscles and glands. Evidently, unless everyone else is using Twitter in a different way to me, it does not introduce any foreign substances into the body. Therefore, any changes in behaviour must be due to the brain changing its own rates of repair and production of different amounts of chemical transmitters. The brain is a wonderful thing and adapts constantly to the new things asked of it, with areas changing shape, size and function. This is something we still know very little about.
Within this massive and still open field, what has Prof Greenfield worked on? She provides a list of her research papers on her website, which is extremely helpful and great practice. In there she lists her commentaries and review, as well as her peer-reviewed, evidence-based research. While we see several pieces on the impact of technology in her commentary section, published in respected venues, this is not a feature of her peer-reviewed work (things she's looked into personally and had competitors and colleagues check over, trying to make sure her work stands up).
For 2011 and 2010, her work is listed as:
1. Hill, M. R. & Greenfield, S. A. The membrane chamber: a new type of in-vitro recording chamber. J Neurosci Methods 195, 15—23, doi:10.1016/j.jneumeth.2010.10.024 (2011).
Here she documents her work on making a device to record brain chemical measurements.
2. Threlfell, S., Greenfield, S. A. & Cragg, S. J. 5—HT(1B) receptor regulation of serotonin (5—HT) release by endogenous 5—HT in the substantia nigra. Neuroscience 165, 212—220, doi:10.1016/j.neuroscience.2009.10.005 (2010).
Here she talks about how a part of the brain manages its serotonin.
3. Halliday, A. C., Kim, O., Bond, C. E. & Greenfield, S. A. Evaluation of a technique to identify acetylcholinesterase C—terminal peptides in human serum samples. Chem—Biol Interact 187, 110—114, doi:10.1016/j.cbi.2010.02.010 (2010).
This is about methods of measuring chemical levels in samples taken from the body.
4. Halliday, A. C., Devonshire, I. M., Greenfield, S. A. & Dommett, E. J. Teaching medical students basic neurotransmitter pharmacology using primary research resources. Adv Physiol Educ 34, 205—212, doi:10.1152/advan.00005.2010 (2010).
Good ways to teach students.
5. Dommett, E. J., Devonshire, I. M., Plateau, C. R., Westwell, M. S. & Greenfield, S. A. From Scientific Theory to Classroom Practice. The Neuroscientist: a review journal bringing neurobiology, neurology and psychiatry, doi:10.1177/1073858409356111 (2010).
Good ways to teach students.
6. Devonshire, I. M., Grandy, T. H., Dommett, E. J. & Greenfield, S. A. Effects of urethane anaesthesia on sensory processing in the rat barrel cortex revealed by combined optical imaging and electrophysiology. The European journal of neuroscience 32, 786—797, doi:10.1111/j.1460—9568.2010.07322.x (2010).
How rats sense when doped.
7. Devonshire, I. M., Dommett, E. J., Grandy, T. H., Halliday, A. C. & Greenfield, S. A. Environmental enrichment differentially modifies specific components of sensory‐evoked activity in rat barrel cortex as revealed by simultaneous electrophysiological recordings and optical imaging in vivo. Neuroscience 170, 662—669, doi:10.1016/j.neuroscience.2010.07.029 (2010).
How the environment affects how rats react.
You might note that the environmental studies cited above are on rats, not big Twitter users, and that the other studies focus on chemical measurements. To my knowledge, noone has published any studies of how social media affects neurochemicals. This might be something Prof Greenfield could look into; she would be very qualified.
So yes, she's studied related areas. But bearing in mind how complicated brains and behaviour are, I think it's a bit of a stretch to say that having studied the way the environment affects the brain (with specific regard to levels of neurochemicals and hormones) means you can talk with knowledge about anything that can affect the brain.
Because here is a list of things that change how your brain behaves (cribbed shamelessly from Adam Rutherford):
So, it's just her opinion. Even for eminent scientists, if you're talking about a field you know nothing of, it's just your opinion.1 Science is not a monolith!
Sure, TV and media, interview her. It sells. But don't make out that she's any better than anyone else on this topic. You might as well have me on to talk about anything that involves electrons and photons.
(Your discovery) is an aid not to memory, but to reminiscence, and you give your disciples not truth, but only the semblance of truth; they will be hearers of many things and will have learned nothing; they will appear to be omniscient and will generally know nothing; they will be tiresome company, having the show of wisdom without the reality.
Yes ladies and gentlemen, it's that well-known brain-rotter writing, as rejected by the father of Philosophy, Socrates.2
When it was politely pointed out that she hasn't published on the impact of cyber communication on the brain (so has no evidence, and hasn't even tried to get any), she responds that she has studied the effect of the environment on the brain — and, for bonus points, accuses her debator of an ad hominem attack.
That's not an ad hominem attack. He's questioning her evidence base for this point, not making personal attacks on her. If you'd like an example of an ad hominem attack, check out when she calls his viewpoint 'solipsistic' or sarcastically refer to Twitter users as 'renaissance men and women'.
When called on her lack of evidence by other people, Prof Greenfield responded by saying those who asked for evidence 'were like the epidemiologists who denied tobacco's link to lung cancer'. This is an example of the hyperbolic analogy, comparing an opponent to a horrible person. It's ad hominem by analogy, essentially.
(I get all my rhetorical tips from It Figures because it's awesome.)
I guess fundamentally though, if she doesn't use social media and hasn't studied its use in other people, one might have to wonder why she's deferred to on telly to talk about it. But never mind because she's a woman scientist in the media, and we certainly need more of those. Right? ... right?