Scientific writing 3.0: A reader and writer's guide - Jean-Luc Lebrun, Justin Lebrun 2021

The word overflow
Require less from memory
The reading toolkit

Memorizing takes a great deal of attention. The process is also slow. Have you ever been able to absorb complex road directions without asking the person to repeat them? Our working memory is not very elastic; it cannot accommodate a sudden word overflow as the next example demonstrates. Before you start reading it, a little background will help. This sentence is about molding machines. These machines melt plastic pellets and inject the molten plastic inside molds to make plastic parts.

“The main difference between the new micro molding machine design and the conventional “ macro ” molding machines with reciprocating screw injection system is that by separating melt plastication and melt injection, a small injection plunger a few millimeters in diameter can be used for melt injection to control metering accuracy, and at the same time a screw design that has sufficient channel depth to properly handle standard plastic pellets and yet provide required screw strength can be employed in micro molding machines.”¹

Chances are you were not able to finish reading this 81-word sentence without having to read again parts of it. Its syntax is acceptable, and the meaning clear enough for a specialist familiar with the machine. But the working memory necessary to process it in one reading is too large for most readers.

When noticing such a long sentence, the writer is often tempted to break it down into two parts, by inserting a full stop in the middle of it.

“The main difference between the new micro molding machine design and the conventional “ macro ” molding machines with reciprocating screw injection system is that by separating melt plastication and melt injection, a small injection plunger a few millimeters in diameter can be used for melt injection to control metering accuracy. At the same time a screw design that has sufficient channel depth to properly handle standard plastic pellets and yet provide required screw strength can be employed in micro molding machines.”

Of course, it helps, but it rarely is the best way to deal with a long sentence.

Before rewriting a long sentence to avoid what computer programmers call memory stack overflow and humans call headache, identify the intent of the author.

This sentence, found in the introduction of the paper, identifies a novel solution. The novelty is buried right in the middle of the long sentence in a place unlikely to attract much attention.

Before breaking down that sentence into multiple sentences, let’s adopt a classic structure: start with the existing problem — then present a new solution. Unlike the original sentence that immediately plunges the reader straight into the core of the innovation, let us start with the known information — the background familiar to the reader.

In conventional “ macro ” molding machines with reciprocating screw injection, melt plastication and melt injection are combined within the screw-barrel system. In the new micro molding machine, screw and injector are separated. The screw, now redesigned, has enough channel depth and strength to handle standard plastic pellets, but the separate injector, now with a plunger only a few millimeters in diameter, enables better control of metering accuracy.

The rewritten paragraph has three sentences instead of one, and 67 words instead of 81. The memory is not strained because the punctuation provides enough pauses for the brain to catch up: two commas and one full stop in the original versus five commas and three full stops in the rewritten version. The new version is also clearer and more concise.

Before we leave this example, and since good writing is also convincing writing, I would like to emphasize something the authors of the original sentence did well. They anticipated that the users of the new ’Micro-Molding’ machines would want to use the same (cheap) plastic pellets that they use in their old ’Macro-Molding’ machines. They may have tons of these pellets stored on wooden pallets in their warehouses. The authors responded to a possible objection by reassuring the users that the redesigned screw is able to handle standard plastic pellets.

The best way to persuade someone to let go of something familiar and adopt something new, is to anticipate and respond to the most common objection people might have when considering the change.

In summary, acronyms, pronouns, synonyms, abusive detailing, background ghettos, cryptic captions, disconnected phrases and long sentences, all take their toll on the reader’s memory.

¹ Zhao J, Mayes RH, Chen GE, Xie H, Chan PS. (2003) “Effects of process parameters on the micro molding process”, Polymer Eng Sci, 43(9): 1542—1554, ©Society of Plastics Engineers