Research science is a very varied discipline, and almost any personal deficit can be compensated for by working with the right team. I for example am clumsy and fairly useless in the lab, but my team are excellent, and so stuff gets done. I’m slow and useless at programming, but ditto. I survive mainly because I can write. I’ve always loved writing and didn’t realise when I embarked on a scientific career that it was so important, but in reality it’s the bulk of my day – papers, grants, reports, reviews, meeting minutes, blog posts, tweets, emails emails emails – a scientist is always writing.
So, how to write well? This is instinctive for some people but not for everyone so I thought I’d have a shot at crystallizing some thoughts. They are based around two simple ideas: one is that the working memory load on the reader should be kept to a minimum, and the other is that the experience should feel as smooth and seamless as possible. These things are achieved by structure, as well as by punctuation and word choice.
The first important thing about a piece is its overall structure. Scientific writing, whether it’s a full paper or just an abstract, has a similar flow:
I. Background and why it’s important
II. A particular problem within this domain that is the focus of the present work, framed as a question or hypothesis
III. A proposal for how to address the question
IV. Specific details of the methods
V. Results, actual or predicted
VI. Implications of the results for the particular question
VII. Implication of the results for the background issue
I think of this as the zoom-in zoom-out approach.
Most people quickly learn about general structuring, not least because it’s often required by the journal or grant format. The micro-structure is often where writers fall down: by this I mean the structure of sections, and within those, the structure of paragraphs, and then, finally, the structure of sentences and choice of words. Let’s take those one at a time.
A section of work has a narrative structure – that is, a story that you are trying to tell. When we tell stories verbally, narrative structure comes naturally: “I was on my way to the shops when I saw a cat chase a dog across the road, and on my way back I found that the dog had trapped the cat in a tree and wouldn’t let it down. I couldn’t stop laughing – serves that cat right”. Even a very short narrative has a temporal order and a logical structure in which the sequence of events makes sense, and is usually followed by some kind of conclusion or take-home message.
This needs to be the case for scientific writing too, although the “events” are not necessarily discrete or temporally ordered. Nevertheless there is a logical flow – A leads to B leads to C – and a single take-home message. When reading other people’s writing, particularly when they are novices, it’s often very hard to discern the narrative trajectory, or extract the take-home message. People often feel they need to be comprehensive and give all the background details they can, but this is not the case. You want to include only the information that the reader needs to journey towards and ultimately understand the take-home message. So, you should start by deciding on what that message is – what one thing do I want the reader to take away from this section? And what do they need to know to get to that thing?
The ideas should also flow along without needing re-visiting. Try to group all of the discussion of a particular topic into the one region, so that the reader is not forced to go back and re-open a topic they had mentally closed earlier. If you present several items for discussion, thus opening a list in the reader’s mind, try to discuss them in the same order so that the reader can travel down their mental list in sequence without backtracking.
A section is broken up into paragraphs, which are visual groupings of sentences based on the common idea they contain. Their function is to help the reader “chunk” (categorize) the information to make it easier to assimilate and remember. Each paragraph should ideally contain one main idea/chunk. The transition from one chunk to the next is cognitively alerting, and a good writer will use this fact to signal to the reader that they should wrap up this idea now because a new one is about to start.
The optimal length of a paragraph somewhat depends on the complexity of the message, but in general, what works well is around 2-4 paragraphs per printed page. Fewer than that and the text appears as one large indigestible mass of words, while if paragraphs are too numerous and short then the writing has a staccato feel and has too many separated ideas to remember easily. These are not rigid rules, however: sometimes longer or shorter paragraphs are needed. To see if this is the case, develop the habit of reading and re-reading and re-re-reading your work as you go, noting how you feel as you read. The experience should feel smooth and undemanding. If it feels jumpy then you may need to glue some of the paragraphs together, or expand each one a little to optimize the chunk size. If you find yourself confused, bored, tired, or feel that you have veered from one topic to another, then your paragraph probably needs splitting.
Within each paragraph there is also a mini-narrative, nested within the larger narrative flow of the whole section. The opening sentence or two introduces the topic of the paragraph, the middle sentences develop it, and the concluding sentence wraps it up, perhaps by summarising the take-home message of that paragraph. The opening sentence will sometimes link to the previous paragraph, when the reader is being asked to use the information from that one to understand the message of this one. For example, it might start: “Based on these findings, we decided to test…” – since “these” clearly refers to the previous paragraph, the reader knows to keep the contents of that paragraph active in their working memory. The final sentence, similarly, will either close the topic, or alert the reader that the thread is to continue. The idea is to use paragraph structure to help readers chunk and order the flow of material.
A sentence is like a paragraph inasmuch as it chunks information so that its core idea can be stored as a kind of mental brick, which the reader uses to build a cognitive edifice. Much of what we said above applies to sentences too, although obviously in a more abbreviated way.
Sentences have their own logical structure, which is that they contain a subject, verb and object. This is so basic it shouldn’t need stating but it is remarkable how often poor writers violate this simple rule. The reason is that in a complex sentence, these elements are made from several words together, called phrases, and because the phrases themselves contain verbs it can be hard to work out which is the verb for the phrase and which is the verb for the whole sentence. For example, “The cat that bit the dog chased the rat that bit the mouse” has three verbs, only one of which is the one for the sentence as a whole. Humans have a remarkable capacity to untangle (“parse”) complex sentences and find the core verb, but a scientific reader’s brain already has a lot of work to do and it is kindest not to load it further. In other words, keep sentences linguistically simple.
How sentences are constructed is one of the most telling indicators of how good a writer is because a number of factors come into play, which a good writer will unconsciously optimize. The available tools are the lexicon (which words you can choose from), the punctuation types and the number and arrangement of these. The aim is to try to achieve balance and flow so that the words and ideas arrive at an optimal rate. When someone reads text they mentally simulate the corresponding speech, so that a longer word (“participants”) takes longer to absorb than a shorter one (“subjects”). This fact can be deployed to create a pleasing rhythm to sentences. At the same time, the words evoke ideas, which are also a form of mental simulation, this time usually as visual imagery (at least in science), and again, the experience is most pleasing when the flow is smooth and logical, with no need to go back and re-open a closed topic. Sometimes a word fails to evoke its corresponding idea immediately – for example, it may not be clear what “this” refers to until further along in the sentence – leading to an uncomfortable moment for the reader. Even worse, sometimes an ambiguous word with an initially assumed meaning needs to have that meaning reassigned later in the sentence – Steven Pinker has a delightful collection of such “garden path” sentences.
As mentioned earlier, the best way to decide if your sentences are well-formed is to read your written work back to yourself over and over, and see how it feels. If there are jarring moments of ambiguity then remove those by adding/removing or re-ordering words. If a sentence feels too terse then maybe you need to add longer or perhaps more words, while if it feels too long then perhaps it should be two sentences. As with paragraphs, a sentence also shouldn’t contain too many ideas. I rely heavily on the two-step procedure – say a thing, and then say a thing about the thing. If I find myself saying a thing about the thing about the thing then I figure I probably need more sentences.
One final word about sentences – commas. I don’t plan to write a book about punctuation (though people do) but the humble comma is a critical part of sentence construction, and is often egregiously misused. I won’t get into the Oxford comma debate, which refers to whether or not a comma (i.e., the Oxford comma) should follow the final item in a list – I don’t really care to be honest, although I tend to avoid Oxford commas unless they resolve an ambiguity. What bothers me more is when people use commas where a proper break was needed – either an em-dash (a long dash like the one I just used), a colon or even a full-stop.
It’s very difficult to find a simple rule for when to use or avoid commas. If you google “commas” then you find long lists of situations where they are misused, which are probably worth memorising if you don’t have an instinct for them. There are also personal differences in comma usage style – I try to be sparing with them and find nothing more irritating than having carefully crafted text come back from a less parsimonious editor with a collection of unnecessary added commas. (I usually remove them in proofing, but they doubtless add them back in!) In general, commas signal to the reader to create a cognitive break, and should be used to separate items in a list or to separate the sub-parts of an idea. They are not for simply breaking up long sentences – the sentence either doesn’t really need breaking or else it should be split, with a proper break signalling a firm transition.
The English language at the same time both lovely and irritating in that it has so many synonyms. Science writers often feel that they should use more formal, Latinate variants of words (“individuals” instead of “people”, “facilitated” instead of “helped”, “utilise” instead of “used”) but this generally makes for a poor reading experience, although it may have the desired effect of making the writer seem more scholarly. In my view it’s better to ditch scholarly artifice in favour of simplicity and clarity.
It is important to find the right tone: neither too formal and flowery nor too familiar and colloquial. I advise students to avoid personal pronouns as a general rule, as I find they interrupt the flow of abstract ideas by suddenly introducing a real person and activating the social brain networks. Sometimes, of course, this is the intended effect – there are no hard and fast rules here.
Reading your writing
The take-home message of this piece is that your writing aims to minimise cognitive load for your readers, by making the structure and content as logically and perceptually smooth as possible so that they can focus on the ideas. Read and re-read your text to see how it feels at each moment along the way. Is your mental experience one of having a smooth and easy ride, or is it a bumpy and difficult one? Are there any “catches” in your experiential flow that suggest an ugly phrase, repeated word, poorly paced rhythm or ambiguous meaning? Does each paragraph lead the reader gently into the following one? Are the concepts flowing naturally one to the next, converging towards a single goal? If the reader can come away from your piece with a clear take-home message, having not really noticed the writing at all, then you have done your job well.