Tuesday 26 June 2018

Preprint publication as karaoke

 Doing research, analysing the results, and writing it up is a prolonged and difficult process. Submitting the paper to a journal is an anxious moment. Of course, you hope the editor and reviewers will love it and thank you for giving them the opportunity to read your compelling research. And of course, that never happens. More often you get comments from reviewers pointing out the various inadequacies of your grasp of the literature, your experimental design and your reasoning, leading to further angst as you consider how to reply. But worse than this is silence. You hear nothing. You enquire. You are told that the journal is still seeking reviewers. If you go through that loop a few times, you start to feel like the Jane Austen heroine who, having dressed up in her finery for the ball, spends the evening being ignored by all the men, while other, superficial and gaudy women are snapped up as dance partners.

There have been some downcast tweets in my timeline about papers getting stuck in this kind of journal limbo. When I suggested that it might help to post papers as preprints, several people asked how this worked, so I thought a short account might be useful.

To continue the analogy, a preprint server offers you a more modern world where you can try karaoke. You don't wait to be asked: you grab the microphone and do your thing. I now routinely post all my papers as preprints before submitting them to a journal. It gets the work out there, so even if journals are unduly slow, it can be read and you can get feedback on it.

So how does it work? Pre-prints are electronic articles that are not peer-reviewed. I hope those who know more about the history will be able to comment on this, as I'm hazy on the details, but the idea started with physicists, to whom the thought of waiting around for an editorial process to complete seemed ridiculous. Physicists have been routinely posting their work on arXiv (pronounced 'archive') for years to ensure rapid evaluation and exchange of ideas. They do still publish in journals, which creates a formal version of record, but the arXiv is what most of them read. The success of arXiv led to the development of BioRxiv, and then more recently PsyArXiv and SocArXiv. Some journals also host preprints - I have had good experiences with PeerJ, where you can deposit an article as a preprint, with the option of then updating it to a full submission to the journal if you wish*.

All of these platforms operate some basic quality control. For instance, the BioRxiv website states: 'all articles undergo a basic screening process for offensive and/or non-scientific content and for material that might pose a health or biosecurity risk and are checked for plagiarism'. However, once they have passed screening, articles are deposited immediately without further review.

Contrary to popular opinion, publishing a preprint does not usually conflict with journal policies. You can check the policy of the journal on the Sherpa/ROMEO database: most allow preprints prior to submission.

Sometimes concerns are expressed that if you post a preprint your work might be stolen by someone who'll then publish a journal article before you. In fact, it's quite the opposite. A preprint has a digital object identifier (DOI) and establishes your precedence, so guards against scooping. If you are in a fast-moving field where an evil reviewer will deliberately hold up your paper so they can get in ahead, pre-printing is the answer.

So when should you submit a preprint? I would normally recommend doing this a week or two before submitting to a journal, to allow for the possibility of incorporating feedback into the submitted manuscript, but, given that you will inevitably be asked for revisions by journal reviewers, if you post a preprint immediately before submission you will still have an opportunity to take on board other comments.

So what are the advantages of posting preprints?

1. The most obvious one is that people can access your work in a timely fashion. Preprints are freely available to all: a particularly welcome feature if you work in an area that has implications for clinical practice or policy, where practitioners may not have access to academic journals.

2. There have been cases where authors of a preprint have been invited to submit the work to a journal by an editor. This has never happened to me, but it's nice to know it's a possibility!

3. You can cite a preprint on a job application: it won't count as much as a peer-reviewed publication, but it does make it clear that the work is completed, and your evaluators can read it. This is preferable to just citing work as 'submitted'. Some funders are now also allowing preprints to be cited. https://wellcome.ac.uk/news/we-now-accept-preprints-grant-applications

4. Psychologically, for the author, it can be good to have a sense that the work is 'out there'. You have at least some control over the dissemination of your research, whereas waiting for editors and reviewers is depressing because you just feel powerless.

5. You can draw attention to a preprint on social media and explicitly request feedback. This is particularly helpful if you don't have colleagues to hand who are willing to read your paper. If you put out a request on Twitter, it doesn't mean people will necessarily reply, but you could get useful suggestions for improvement and/or make contact with others interested in your field.

On this final point, it is worth noting that there are several reasons why papers linger in journal limbo: it does not necessarily mean that the journal administration or editor is incompetent (though that can happen!). The best of editors can have a hard job finding reviewers: it's not uncommon to have to invite ten reviewers to find two who agree to review. If your papers is in a niche area then it gets even harder. For these reasons it is crucial to make your title and abstract as clear and interesting as possible: these are the only parts of the paper that potential reviewers will see, and if you are getting a lot of refusals to review, it could be that your abstract is a turn-off. So asking for feedback on a preprint may help you rewrite it in a way that encourages more interest from reviewers.

*Readers: please feel free to add other suggestions while comments are open. (I close comments once the invasion of spammers starts - typically 3-4 weeks after posting).

Saturday 9 June 2018

Developmental language disorder: the need for a clinically relevant definition

There's been debate over the new terminology for Developmental Language Disorder (DLD) at a meeting (SRCLD) in the USA. I've not got any of the nuance here, but I feel I should make a quick comment on one issue I was specifically asked about, viz:

As background: the field of children's language disorders has been a terminological minefield. The term Specific Language Impairment (SLI) began to be used widely in the 1980s as a diagnosis for children who had problems acquiring language for no apparent reason. One criterion for the diagnosis was that the child's language problems should be out of line with other aspects of development, and hence 'specific', and this was interpreted as requiring normal range nonverbal IQ (nviq).

The term SLI was never adopted by the two main diagnostic systems -WHO's International Classification of Diseases (ICD) or the American Psychiatric Association's Diagnostic and Statistical Manual (DSM), but the notion that IQ should play a part in the diagnosis became prevalent.

In 2016-7 I headed up the CATALISE project with the specific goal of achieving some consensus about the diagnostic criteria and terminology for children's language disorders: the published papers about this are openly available for all to read (see below). The consensus of a group of experts from a range of professions and countries was to reject SLI in favour of the term DLD.

Any child who meets criteria for SLI will meet criteria for DLD: the main difference is that the use of an IQ cutoff is no longer part of the definition. This does not mean that all children with language difficulties are regarded as having DLD: those who meet criteria for intellectual disability, known syndromes or biomedical conditions are treated separately (see these slides for summary).

The tweet seems to suggest we should retain the term SLI, with its IQ cutoff, because it allows us to do neatly controlled research studies. I realise a brief, second-hand tweet about Rice's views may not be a fair portrayal of what she said, but it does emphasise a bone of contention that was thoroughly gnawed in the discussions of the CATALISE panel, namely, what is the purpose of diagnostic terminology? I would argue its primary purpose is clinical, and clinical considerations are not well-served by research criteria.

The traditional approach to selecting groups for research is to find 'pure' cases - quite simply, if you include children who have other problems beyond language (including other neurodevelopmental difficulties) then it is much harder to know how far you are assessing correlates or causes of language problems: things get messy and associations get hard to interpret. The importance of controlling for nonverbal IQ has been particularly emphasised over many years: quite simply, if you compare language-impaired vs comparison (typically-developing, or td) children on a language or cognitive measure, and the language-impaired group has lower nonverbal ability, then it may be that you are looking at a correlate of nonverbal ability rather than language. Restricting consideration to those who meet stringent IQ criteria to equalise the groups is one way of addressing the issue.

However, there are three big problems with this approach:

1. A child's nonverbal IQ can vary from time to time and it will depend on the test that is used. However, although this is problematic, it's not the main reason for dropping IQ cutoffs; the strongest arguments concern validity rather than reliability of an IQ-based approach.

2. The use of IQ-cutoffs ignores the fact that pure cases of language impairment are the exception rather than the rule. In CATALISE we looked at the evidence and concluded that if we were going to insist that you could only get a diagnosis of DLD if you had no developmental problems beyond language, then we'd exclude many children with language problems (see also this old blogpost). If our main purpose is to get a diagnostic system that is clinically workable, it should be applicable to the children who turn up in our clinics - not just a rarefied few who meet research criteria. An analogy can be drawn with medicine: imagine if your doctor identified you with high blood pressure but refused to treat you unless you were in every other regard fit and healthy. That would seem both unfair and ill-judged. Presence of co-occurring conditions might be important for tracking down underlying causes and determining a treatment path, but it's not a reason for excluding someone from receiving services.

3. Even for research purposes, it is not clear that a focus on highly specific disorders makes sense. An underlying assumption, which I remember starting out with, was the idea that the specific cases were in some important sense different from those who had additional problems. Yet, as noted in the CATALISE papers, the evidence for this assumption is missing: nonverbal IQ has very little bearing on a child's clinical profile, response to intervention, or aetiology. For me, what really knocked my belief in the reality of SLI as a category was doing twin studies: typically, I'd find that identical twins were very similar in their language abilities, but they sometimes differed in nonverbal ability, to the extent that one met criteria for SLI and the other did not. Researchers who treat SLI as a distinct category are at risk of doing research that has no application to the real world.

There is nothing to stop researchers focusing on 'pure' cases of language disorder to answer research questions of theoretical interest, such as questions about the modularity of language. This kind of research uses children with a language disorder as a kind of 'natural experiment' that may inform our understanding of broader issues. It is, however, important not to confuse such research with work whose goal is to discover clinically relevant information.

If practitioners let the theoretical interests of researchers dictate their diagnostic criteria, then they are doing a huge disservice to the many children who end up in a no-man's-land, without either diagnosis or access to intervention. 


Bishop, D. V. M. (2017). Why is it so hard to reach agreement on terminology? The case of developmental language disorder (DLD). International Journal of Language & Communication Disorders, 52(6), 671-680. doi:10.1111/1460-6984.12335

Bishop, D. V. M., Snowling, M. J., Thompson, P. A., Greenhalgh, T., & CATALISE Consortium. (2016). CATALISE: a multinational and multidisciplinary Delphi consensus study. Identifying language impairments in children. PLOS One, 11(7), e0158753. doi:10.1371/journal.pone.0158753

Bishop, D. V. M., Snowling, M. J., Thompson, P. A., Greenhalgh, T., & CATALISE Consortium. (2017). Phase 2 of CATALISE: a multinational and multidisciplinary Delphi consensus study of problems with language development: Terminology. Journal of Child Psychology and Psychiatry, 58(10), 1068-1080. doi:10.1111/jcpp.12721