Friday, 26 September 2014

Why most scientists don't take Susan Greenfield seriously


Three years ago I wrote an open letter to Susan Greenfield, asking her to please stop claiming there is a link between autism and use of digital media. It’s never pleasant criticizing a colleague, and since my earlier blogpost I’ve held back from further comment, hoping that she might refrain from making claims about autism, and/or that interest in her views would just die down. But now she's back, reiterating the claims in a new book and TV interview, and I can remain silent no longer.

Greenfield featured last week as the subject of a BBC interview in the series Hard Talk. The interviewer, Stephen Sackur, asked her specifically if she really believed her claims that exposure to modern digital media – the internet, video games, social media – were damaging to children’s development. Greenfield stressed that she did: although she herself had not done direct research on the internet/brain impact link, there was ample research to persuade her it was real. Specifically, she stated: “.. in terms of the evidence, anyone is welcome to look at my website, and it’s been up there for the last year. There’s 500 peer-reviewed papers in support of the possible problematic effects.”

A fact-check on the “500 peer-reviewed papers”

So I took a look. The list can be downloaded from here: it’s not exactly a systematic review. I counted 395 distinct items, but only a small proportion are peer-reviewed papers that find evidence of adverse effects from digital technology. There are articles from the Daily Mail and reports by pressure groups. There are some weird things that seem to have found their way onto the list by accident, such as a report on the global tobacco epidemic, and another from Department of Work and Pensions on differences in life expectancy for 20-, 50- and 80-year-olds. I must confess I did not read these cover to cover, but a link with 'mind change' was hard to see. Of the 234 peer-reviewed papers, some are reports on internet trends that contain nothing about adverse consequences, some are straightforward studies of neuroplasticity that don’t feature the internet, and others are of uncertain relevance. Overall, there were 168 papers that were concerned with effects of digital technology on behaviour and 15 concerned with effects on the brain. Furthermore, a wide range of topics was included: internet addiction, Facebook and social relations, violent games and aggression, reading on screens vs books, cyberbullying, ‘brain training’ and benefits for visuospatial skills, effects of multitasking on attention. I could only skim titles and a few abstracts, but I did not come away feeling there was overwhelming evidence of adverse consequences of these new technologies. Rather, papers covered a mix of risks and benefits with varying quality of evidence. There is, for instance, a massive literature on Facebook influences on self-esteem and social networks, but much of it talks of benefits. The better studies also noted the difficulties of inferring causation from correlational data: for instance, it’s possible that an addictive attitude to a computer game is as much a consequence as a cause of problems with everyday life.

Greenfield’s specific contribution to this topic is to link it up with what we know about neuroplasticity, and she has speculated that attentional mechanisms may be disrupted by effects that games have on neurotransmitter levels, that empathy and social relationships can be damaged when computers/games take us away from interacting with people, and that too much focus on a two-dimensional screen may affect perceptual and cognitive development in children. This is all potentially important and a worthy topic for research, but is it reasonable, as she has done, to liken the threat to that posed by climate change? As Stephen Sackur pointed out, the evidence from neuroplasticity would indicate that if the brain changes in response to its environment, then we should be able to reverse an effect by a change in environment. I cannot resist also pointing out that if it is detrimental to perform socially-isolated activities with a two-dimensional surface rather than interacting with real people in a 3D world, then we should be discouraging children from reading books.

Digital media use as a risk factor for autism

My main concern is the topic that motivated me to write to Greenfield in the first place: autism. The arguments I put forward in 2011 still stand: it is simply irresponsible to indulge in scaremongering on the basis of scanty evidence, particularly when the case lacks logical consistency.

In the Hard Talk interview*, Greenfield attempted to clarify her position: “You have to be careful, because what I say is autistic spectrum disorder. That’s not the same as autism.” Yet this is no clarification at all, given that the latest edition of DSM5 states: “Individuals with a well-established DSM-IV diagnosis of autistic disorder, Asperger’s disorder, or pervasive developmental disorder not otherwise specified should be given the diagnosis of autism spectrum disorder (ASD).” Greenfield has had a few years to check her facts, yet seems to be under the impression that ASD is some kind of mild impairment like social gaucheness, quite distinct from a clinically significant condition.

In an interview in the Observer (see here**), Greenfield was challenged by the interviewer, Andrew Anthony, who mentioned my earlier plea to her to stop talking about autism. She replied to say that she was not alone in making the link and that there were published papers making the same case. She recommended that if I wanted to dissent, I should “slug it out” with the authors of those papers. That’s an invitation too good to resist, so I searched the list from her website to find any that mentioned autism. There were four (see reference list below):

We need not linger on the Hertz-Picciotto & Delwiche paper, because it focuses on changes in rates of autism diagnosis and does not mention internet use or screen time. The rise is a topic of considerable interest about which a great deal has been written, and numerous hypotheses have been put forward to explain it. Computer use is not generally seen as a plausible hypothesis because symptoms of ASD are typically evident by 2 years of age, long before children are introduced to computers. (Use of tablets with very young children is increasing, but would not have been a factor for the time period studied, 1990-2006).

The Finkenauer et al paper is a study of internet use, and compulsive internet use by married couples, who were assessed using self-report questionnaires. Frequency of internet use was not related to autistic traits, but compulsive internet use was. The authors did not conclude that internet use causes autistic traits – that would be a bit weird in a sample of adults who grew up before the internet was widespread. Instead, they note that if you have autistic traits, there is an increased likelihood that internet use could become problematic. The paper is cautious in its conclusions and does not support Greenfield’s thesis that the internet is a risk factor for autism. On the contrary, it emphasises the possibility that people who develop an addictive relationship with the internet may differ from others in pre-existing personality traits.

So on to Waldman et al, who consider whether television causes autism. Yes, that’s right, this is not about internet use. It’s about the humble TV. Next thing to note is this is an unpublished report, and not a peer-reviewed paper. So I checked out the authors to see if they had published anything on this, and found an earlier paper with the intriguing title: “Autism Prevalence and Precipitation Rates in California, Oregon, and Washington Counties”. Precipitation? Like, rainfall? Yup! The authors did a regression analysis and concluded that there was a statistically significant association between the amount of rainfall in a specific county, and the frequency of autism diagnoses. They then went on to consider why this might be, and came up with an ingenious explanation: when it is wet, children can’t play outside. So they watch TV. And develop autism.

In the unpublished report, the theme is developed further, by linking rate of precipitation to household subscription to cable TV. The conclusion:

“Our precipitation tests indicate that just under forty percent of autism diagnoses in the three states studied is the result of television watching due to precipitation, while our cable tests indicate that approximately seventeen percent of the growth in autism in California and Pennsylvania during the 1970s and 1980s is due to the growth of cable television.”

One can only breathe a sigh of relief that no peer-reviewed journal appears to have been willing to publish this study.

But wait, there is one more study in the list provided by Greenfield. Will this be the clincher? It's by Maxson McDowell a Jungian therapist who uses case descriptions to formulate a hypothesis that relates autism to “failure to acquire, or retain, the image of the mother’s eyes”. I was initially puzzled at inclusion of this paper, because the published version blames non-maternal childcare rather than computers, but there is an updated version online which does make a kind of link – though again not with the internet: “The image-of-the-eyes hypotheses suggest that this increase [in autism diagnoses] may be due to the increased use, in early infancy, of non-maternal childcare including television and video.” So, no data, just anecdote and speculation designed to make working mothers feel it’s their fault that their child has autism.

Greenfield's research track record

Stephen Sackur asked Greenfield why, if she thought this topic so important, she hadn’t done research on this topic herself. She replied that as a neuroscientist, she couldn't do everything, that research costs money, and that if someone would like to give her some money, she could do such research.

But someone did give her some money. According to this website, in 2005 she received an award of $2 million from the Templeton Foundation to form the Oxford Centre for Science of the Mind which is “dedicated to cutting-edge interdisciplinary work drawing on pharmacology, human anatomy, physiology, neuroscience, theology and philosophy". A description of the research that would be done by the centre can be found here. Most scientists will have experienced failure to achieve all of the goals that they state in their grant proposals – there are numerous factors outside one's control that can mess up the best-laid plans. Nevertheless, the mismatch between what is promised on the website and evidence of achievement through publications is striking, and perhaps explains why further funding has apparently not been forthcoming.

One of the more surprising comments by Greenfield was when Sakur mentioned criticism of her claims by Ben Goldacre. “He’s not a scientist,” she retorted, “he’s a journalist”. Twitter went into a state of confusion, wondering whether this was a deliberate insult or pure ignorance. Goldacre himself tweeted: “My publication rate is not stellar, as a part time early career researcher transferring across from clinical medicine, but I think even my peer reviewed publication rate is better than Professor Greenfield's over the past year.”

This is an interesting point. The media repeatedly describe Greenfield as a “leading neuroscientist”, yet this is not how she is currently perceived among her peer group. In science, you establish your reputation by publishing in the peer-reviewed literature. A Web of Science search for the period 2010-2014 found thirteen papers in peer-reviewed journals authored or co-authored by Greenfield, ten of which reported new empirical data. This is not negligible, but for a five-year period, it is not stellar - and represents a substantial fall-off from her earlier productivity.

But quality is more important than quantity, and maybe, you think, her work is influential in the field. To check that out, I did a Web of Science search for papers published from a UK address between 2005-2014 with topic specified as (Alzheimer* OR Parkinson’s OR neurodegener*) AND brain. (The * is wildcard, so this will capture all words starting this way). I used a 10-year period because citations (a rough measure of how influential the work is) take time to accrue. This yielded over 3,000 articles, which I rank ordered by the number of citations. The first paper authored by Greenfield was 956th in this list: “Non-hydrolytic functions of acetylcholinesterase - The significance of C-terminal peptides”, with 21 citations.

Her reputation appears to be founded on two things: her earlier work, in basic neuroscience in the 1980s and 1990s, which was well-cited, and her high profile as a public figure. Sadly, she seems to now be totally disconnected from mainstream science.

If Greenfield seriously believes in what she is saying, and internet use by children is causing major developmental difficulties, then this is a big deal. So why doesn’t she spend some time at IMFAR, the biggest international conference on autism (and autism spectrum disorder!)  that there is? She could try presenting her ideas and see what feedback she gets. Better still, she could listen to other talks, get updated on current research in this area, and talk with people with autism/ASD and their families.

*For a transcript of the Hard Talk interview see here
 **Thanks for Alan Rew for providing the link to this article

Update: 2nd June 2015: A shortened, version of this blogpost is now posted on the Winnower.


Finkenauer, C., Pollman, M.M.H., Begeer, S., & Kerkhof, P. (2012). Examining the link between autistic traits and compulsive Internet use in a non-clinical sample. Journal of Autism and Developmental Disorders, 42, 2252-2256. doi:10.1007/s10803-012-1465-4

Hertz-Picciotto, I., & Delwiche, L. (2009). The rise in autism and the role of age at diagnosis. Epidemiology, 20(1), 84-90. doi:10.1097/EDE.0b013e3181902d15.

McDowell, M. (2004). Autism, early narcissistic injury and self-organization: a role for the image of the mother's eyes? Journal of Analytical Psychology, 49 (4), 495-519 DOI: 10.1111/j.0021-8774.2004.00481.x

Waldman M, Nicholson S, Adilov N, and Williams J. (2008). Autism prevalence and precipitation rates in California, Oregon, and Washington counties. Archives of Pediatrics & Adolescent Medicine, 162,1026-1034.

Waldman, M., Nicholson, S., & Adilov, N. (2006). Does television cause autism? (Working Paper No. 12632). Cambridge, MA: National Bureau of Economic Research.

Sunday, 14 September 2014

International reading comparisons: is England really doing so poorly?

I was surprised to see a piece in the Guardian stating that "England is one of the most unequal countries for children's reading levels, second in the EU only to Romania". This claim was made in an article about a new campaign, Read On, Get On, that was launched this week.

The campaign sounds great. A consortium of organizations and individuals have got together to address the problem of poor reading: the tail in the distribution of reading ability that seems to stubbornly remain, despite efforts to reduce it. Poor readers are particularly likely to come from deprived backgrounds, and their disadvantage will be perpetuated, as they are at high risk of leaving school with few qualifications and dismal employment prospects. I was pleased to see that the campaign has recognized weak language skills in young children as an important predictor of later reading difficulties. The research evidence has been there for years (Kamhi & Catts, 2011), but it has taken ages to percolate into practice, and few teachers have any training in language development.

But! You knew there was a 'but' coming. It concerns the way the campaign has used evidence. They've mostly based what they say on the massive Progress in International Reading Literacy Study (PIRLS), and the impression is they have exaggerated the negative in order to create a sense of urgency.

I took a look at the Read On Get On report. The language is emotive and all about blame: "The UK has a sorry history of educational inequality. For many children, this country provides enormous and rich opportunities. At the top end of our education system we rival the best in the world. But it has long been recognised that we let down too many children who are allowed to fall behind. Many of them are condemned to restricted horizons and limited opportunities." I was particularly interested in the international comparisons, with claims such as "The UK is one of the most unfair countries in the developed world."

So how were such conclusions reached? Read On, Get On commissioned the National Foundation for Educational Research (NFER) to compare levels of reading attainment in the UK with that of other developed countries, with a focus on children approaching the last year of primary schooling.

Given the negative tone of "letting down children", it was interesting to read that "In terms of its overall average performance, NFER’s research found England to be one of the best performing countries." I put that in bold because, somehow, it didn't make it into the Guardian, so is easy to miss. It is in any case dismissed by the NFER report in a sentence: "As a wealthy country with a good education system, that is to be expected."

The evidence of the parlous state of UK education came from consideration of the range of scores from best (95th percentile) to worst (5th percentile) for children in England. Now this is where I think it gets a bit dishonest. Suppose there were a massive improvement in scores for a subset of children, such that the mean and highest scores went up, but with the lowest scoring still doing poorly; presumably, the shrill voices would get even shriller, because the range would extend even further. This seems a tad unfair: yes, it makes sense to stress that the average attainment doesn't capture important things, and that a high average is not a cause for congratulation if it is associated with a long straggly tail of poor achievers. But if we want to focus on poor achievers, let's look at the proportion of children scoring at a low level, and not at some notional 'gap' between best and worst, which is then translated into 'years' to make it sound even more dramatic.

The question is how does England compare with other countries if we just look at the absolute level of the low score corresponding to the 5th percentile. Answer: not brilliant – 16th out of the 24 countries featured in the subset considered by the NFER survey. But, rather surprisingly, we find that the NFER survey excluded New Zealand and Australia, both of whom did worse than England.

So do we notice anything about that? Well, in all three countries, children are learning English, a language widely recognized as creating difficulty for young readers because of the lack of consistent mapping between letters (orthography) and sounds (phonology). In fact, when looking for sources for this blogpost, I happened upon a report from an earlier tranche of PIRLS data, which examined this very topic, by assigning an 'orthographic complexity' score to different languages. The authors found a correlation of .6 between the range of scores (5th to 95th percentile again, this time for 2003 data) and a measure of complexity of the orthography. I applied their orthography rating scale to the 2011 PIRLS data and found that, once again the range of reading scores was significantly related to orthography (r = .72), with the highest ranges for those countries where English was spoken – see Figure below. (NB it would be very interesting to extend this to include additional countries: I was limited to the languages with an orthographic rating from the earlier report).
PIRLS 2011 data: range of reading attainment vs. orthographic complexity
International comparisons have their uses, and in this case they seem to suggest that a complex orthography widens the gap between the best and worst readers. However, they still need to be treated with caution. I haven't had time to delve into PIRLS in any detail, but just looking at how samples of children were selected, it is clear that criteria varied. In particular, there were differences from country to country in terms of whether they excluded children who were non-native speakers of the test language, and whether they included those with special educational needs. Romania, which had the most extreme range of scores between best and worst, excluded nobody. Finand, which tends to do well in these surveys, excluded "students with dyslexia or other severe linguistic disorders, intellectually disabled students, functionally disabled students, and students with limited proficiency in the assessment language." England excluded "students with significant special educational needs". Needless to say, all of these criteria are open to interpretation.

I'm not saying that the tail of the distribution is unimportant. Yes, of course, we need to do our best to ensure that all children are competent readers, as we know that poor literacy is a major handicap to a person's prospects for employment, education and prosperity. But let's stop beating ourselves over the head about this. Research indicates that the reasons for children's literacy problems are complex and will be influenced by the writing system they have to learn (Ziegler & Goswami, 2005) and constitutional factors (Asbury & Plomin, 2013), as well as by the home and school environment: we still have only a poor grasp of how these different factors interact. Until we gain a better understanding, we should of course put in our best efforts to help those children who are struggling. The enthusiasm and good intentions of those behind Read On, Get On are to be welcomed, but their spin on the PIRLS data is unhelpful in implying that only social factors are important.

Asbury K, and Plomin R. 2013. G is for genes: The impact of genetics on education and achievement. Chichester: Wiley Blackwell.

Kamhi AG, and Catts HW. 2011. Language and Reading Disabilities (3rd Edition): Allyn & Bacon.

Ziegler JC, & Goswami U (2005). Reading acquisition, developmental dyslexia, and skilled reading across languages: a psycholinguistic grain size theory. Psychological bulletin, 131 (1), 3-29 PMID: 15631549