6 - Previous reading research

6.1 - The reading process: physiology and psychology

Reading is a complex physiological and psychological process involving the eyes, the visual cortex, and both sides of the brain. Memory is key to reading, from the simple and mundane act of recognizing a single letter, to comprehending a whole sentence or passage of text. (Taylor & Taylor, 1983: The Psychology of Reading)

Reading psychology and physiology are tied inextricably to the development of human language and writing systems. Methods of printing books and documents were a groundbreaking development only in that they enabled mass production of what had previously been a manual task requiring perhaps years of labor by a scribe.

By the time printing systems appeared, writing was already a very mature technology. Johannes Gutenberg was not the “Thomas Alva Edison” of writing systems. He was the “Henry Ford”, who worked out how to turn what was previously a hand-built technology into a system for mass production.

The writing system itself remained basically unchanged. In fact, the first typefaces were designed to emulate as nearly as possible the calligraphy of scribes.

Writing and reading were a natural outgrowth of the human instinct for pattern-recognition. Pictures were drawn to represent animals and other objects as early as 20,000 BC – the Stone Age. Reading and writing systems were in existence in North Babylonia 8000 years ago. Alphabet signs were used in Egypt at least 7000 years ago.

A detailed history of the evolution of reading and writing (also one of the earliest and most widely quoted works on the psychology and physiology of reading) is found in The Psychology and Pedagogy of Reading (HUEY, 1915).

6.2 - How we read

A huge amount of work has been done, and many books and scientific papers have been written, on how we read. Researchers have dived down into incredible levels of detail, and several different models of how memory works in reading have emerged. There are disputes about the roles of long- and short-term memory for example.

However, all researchers agree that the primary task in reading is pattern recognition. There are disputes about the length of patterns we recognize – individual letters, whole words, groups, phrases and sentences - and how these are assembled, parsed and given meaning by the human mind. But all agree we recognize patterns and then mentally process them in some way.

The traditional approach to teaching reading was to first teach the alphabet of letters, then teach words. Other systems have emerged which concentrate first on whole words.

While the letter-then-word system held sway for languages with alphabets, in languages with logographies such as Chinese, the method of teaching is based on learning words first – since a single character is a word or phrase. Later, children learn the meanings of the component parts or strokes of those characters.

Teaching of reading in alphabet-based systems has moved towards the latter model in past decades, focusing more on words than the basic alphabet, which is learned in the process.

Taylor and Taylor suggest both letter- and word-recognition theories are valid. Poor readers often do not progress beyond the stage of having to identify individual letters before they can recognize a word. Even the adept reader who comes across an unfamiliar word will fall back to recognizing word-parts and even single letters. Ability to use words rather than letters as a unit increases with age and reading skill.

6.3 - Saccades and fixations

French oculist Emile Javal in 1906 made the surprising discovery that we read, not with a smooth sweep of the eyes along a line of print, but by moving our viewpoint in a series of jumps or saccades and carrying out recognition during pauses or fixations.

The reader focuses the image of the text upon the retina, the screen of photosensitive receptors at the back of the eyeball. The retina as a whole has a 240-degree field of vision, but has its maximum resolution in a tiny area at the center of the field called the fovea which is only about 0.2mm in diameter. Foveal vision has a field of only one or two degrees at most (Taylor &Taylor). Huey suggested its field of vision was only about 0.75 of a degree of arc. Outside the fovea is the parafovea, three millimeters in diameter and with a field of around ten degrees. From there vision becomes progressively less clear all the way out to the periphery of the retinal field.

Target words are brought into the fovea by a saccade. After information is acquired during a fixation, another saccade moves to the next target word. Occasionally, the eyes jump back to a previous word for clarification of incomplete perception (or in some cases, just to enjoy a particular passage a certain time, or to help with semantic understanding of a complex passage).

Information is gathered by foveal vision. Parafoveal vision is used to determine locations of following fixations.

These eye movements are under constant cognitive control.

6.4 - Shape and rhythm are critical

Readers learn to recognize words, not letters, although individual letters can help word recognition.

Thus the shapes of letters, and the way they are assembled together into words, are critical to ease of reading.

Huey makes it clear that the way in which the stream of words is presented to the reader’s eye is also critical. “Lines of varying length lead to a more cautious mode of eye movement… and may cause unnecessarily slow readers”. Elsewhere, he says “…when other conditions are constant, reading rates depend largely upon the ease with which a regular, rhythmical movement can be established and sustained.”

Letter shapes and the way they are assembled into words and presented to the reader is the domain of typography.

In the next section we will examine how typography has developed to take advantage of the instinctive human behavior of pattern recognition. We will show how the properly typeset book is a sophisticated yet largely invisible technology deliberately constructed to hook human attention by making this pattern recognition process automatic and unconscious.

Barriers to effective reading. Huey suggests that bad lighting and bad posture are the two most common causes of reading fatigue.

Too great a distance between desk and seat causes problems, and correct reading angle – which must be matched to the height of the reader - is also necessary. Consider the difference between reading a book (normally held at an angle of 45-degrees) and reading from today’s CRT computer monitors (which place text at a 90-degree angle to the reader). This is an effective argument for a tilting screen which can be placed below the reader’s sight horizon, as seen in the latest flat-panel LCD displays, or for an eBook which can be easily held in the hand or placed on a tilting stand.

6.5 - Typographic research

A huge amount of typographic research has been conducted this century, most of it related to legibility in print. The most prolific of the typographic researchers has been without question Professor Miles Tinker of the University of Minnesota, who with his colleague Donald Paterson published dozens of research papers and a number of books summarizing experiments with thousands of subjects. By 1940, Tinker and Paterson had already given speed of reading tests Tinker had devised to 33,000+ subjects, and he and Paterson continued to work in this field for more than 20 years.

Tinker attempted to evaluate all of the variables in turn: typefaces, type sizes, line length, leading, etc.. In many cases, he reached conclusions that can serve as fixed guidelines for setting readable type. Many of these seem relatively obvious in retrospect, but they have value since they are confirmed by scientific data. However, it must be continually kept in mind that Tinker’s testing was on relatively short passages. Small differences in reader preferences that might be acceptable in shorter reading tasks are likely to become magnified the longer the duration of reading.

The most complete summary of their work is contained in Legibility of Print (1963).

For example:

Typeface. Typefaces in common use are equally legible. Tinker cites faces such as Scotch Roman, which was in widespread use at that time for school textbooks.

Readers prefer a typeface that appears to border on “boldface”, such as Antique or Cheltenham. Sanserif faces are read as rapidly as ordinary type, but readers do not prefer it.

Type style. Italics are read slower than ordinary lower-case roman. While bold type is read at the same speed as roman, seventy percent of readers preferred ordinary lower case. So neither italics nor boldface should be used for large amounts of text, but should be kept for emphasis only.

Type size. 11-point type is read significantly faster than 10 point – but 12 point was read slightly more slowly. 8-and 9-point types are significantly less readable, and once the type size rises to 14 points, efficiency is again reduced. This finding is extremely important when it comes to designing books to be read on the screen, since displaying type on screen at sizes anywhere below 14-point presents technical difficulties due to poor screen resolution. This key issue is addressed later in this paper in describing a new innovative display technology capable of solving these difficulties even on the screen resolutions of today.

Line length. Standard printing practices of between eight and 12 words to the line are preferred by readers. Relatively long and short lines are disliked.

Leading. Readers definitely prefer type set with “leading” or additional space between lines. 10-point type, for instance, is preferred with an additional two points of leading added between the lines. More leading than this begins to counter the beneficial effect.

As a general principle, at body text sizes, an additional 20 percent of space should be added, although type size, leading and line length are inter-related variables, none of which can be designed in isolation.

Tinker defines a series of “safe zones” or effective combinations for type sizes from 6 to 12 points.

Page size and margins. Tinker makes no recommendation on page size other than calling for publishers, printers and paper manufacturers to agree on standards. This suggests that the page sizes in common use are satisfactory. The experiments on line length confirm this. Tinker’s experiments showed that readers preferred material with margins, although experimental work showed material without margins was just as legible. This is one of the areas where Tinker’s testing techniques using relatively short-duration reading tasks may well mask a deeper effect which in short-duration tasks is expressed only as a reader preference, but on a longer-duration task such as book reading may surface as an irritation.

Color of print and background. Black print on a white background is much more legible than the reverse. Printed material on the whole is perceived better as the brightness contrast between print and paper becomes greater. Reading rates are the same for colored ink on colored paper, provided high contrast is maintained.

Tinker’s work, while focused often on single variables, recognized that typography was a system of many inter-related variables. If only two or three of those variables were degraded from optimum settings, he found that this was accompanied by a rapidly-increasing loss in legibility.

6.6 - The book as a “system”: Tschichold and Dowding

To truly understand the typography of the book as a “system”, we have to examine the work of specialists in book typography. It is here that analysis often runs into difficulties, since many typographers and designers speak in a language with its own esoteric terms.

The best typographers I have met or read, though, all agree on one point: the purpose of typography in a book is to become invisible. We can re-state this in more scientific terms as “making the reading process as transparent as possible for the reader”. Good typography is meant to pass unnoticed, although achieving it requires an astonishing attention to detail that the lay person can easily misconstrue as “unnecessary fussiness” or even “just art”.

Typographers and designers talk often in terms such as the color of a page (a uniform grayness in which no single word, letter or space stands out from the whole). “Nothing should jump out at you” is another frequent assertion, or “Typography should honor the content”.

What do these unscientific terms really mean? For a detailed analysis of book typography, the reader can do no better than to read in its entirety The Form of the Book, by the eminent 20th Century typographer Jan Tschichold.

6.7 - Tschichold: the rebel who recanted

Tschichold’s own history is of great value in the search for readability in books. He was one of the “young rebels” who in the 1920s and 30s led the “revolution” in typography that was meant to overthrow centuries of hidebound tradition.

Tschichold was one of the leading lights of the “New Typography” of that time, in which the rebels eschewed the conventions of the past. Serif typefaces were passé, and text was to be set ragged right, with no indents for paragraphs but instead with additional space between them.

Tschichold was such a leading light among these revolutionaries that in 1933 he was imprisoned by the Nazi Government for six weeks for his “subversive ideas”. Perhaps they wanted to make certain that the traditional “Aryan” values they believed to be embodied in the Gothic blackletter in common use in Germany and Austria at that time were not diluted by “non-Aryan” typography, taking the same attitude to “modern” typography as they took to modern art.

Tschichold fled to Switzerland with his wife and infant son, and spent most of his life in that country until he died in 1974. He spent two years in London at Penguin books, which was at that time the largest publisher of paperback books in the world.

Within two years of leaving Germany, Tschichold began to step back from his revolutionary theories. “The Form of the Book”, a series of essays published in 1975, a year after his death, shows that in the course of the next 30 years he had fully recanted. It is of all the more value because Tschichold clearly took none of the “print conventions”, as they have been described elsewhere, at face value. All were rejected, and then returned to in the light of experience.

Tschichold’s writings are especially valuable because he expressed good book typography and how to achieve it in extremely scientific terms. His work is summarized below, although it contains far more detail which cannot be ignored of good typography is to be achieved on the screen.

6.8 - Achieving good typography

“Perfect Typography depends on perfect harmony between all of its elements. It is determined by relationships or proportions, which are hidden everywhere; in the margins, in the relationships of the margins to each other, between leading of the type and the margins, placement of page number relative to type area, in the extent to which capital letters are spaced differently from the text, and not least in the spacing of the words themselves.

Comfortable legibility is the absolute benchmark for all typography, and the art of good typography is eminently logical.

Leading, letterspacing and wordspacing must be faultless.

The book designer has to be the loyal and tactful servant of the written word.

Though largely forgotten today, methods and rules on which it is impossible to improve have been developed over centuries. The book designer strives for perfection which is frequently mistaken for dullness by the insensitive. A really well-designed book is recognizable as such only by a select few. The large majority of readers will have only a vague sense of its exceptional qualities.

Typography that cannot be read by everybody is useless. Even with no knowledge, the average reader will rebel at once when the type is too small or otherwise irritates the eye. (We may not know about Art, but we know what we like!)

First and foremost, the form of the letters themselves contributes much to legibility or its opposite. Spacing, if it is too wide or compressed, will spoil almost any typeface.

We cannot change the characteristics of a single letter without at the same time rendering the entire typeface alien and therefore useless.

The more unusual the look of a word we have read – that is to say, recognized – a million times in familiar form, the more we will be disturbed if the form has been altered. Unconsciously, we demand the shape to which we have been accustomed. Anything else alienates us and makes reading difficult.

Small modifications are thinkable, but only within the basic form of the letter.”

6.9 - Back to the classical approach

After fifty years of experimentation – and indeed being one of the leading lights of “innovation” and “revolution”, Tschichold concluded “the best typefaces are either the classical fonts themselves, recuttings of them, or new typefaces not drastically different from the classical pattern”.

Sanserif faces are more difficult to read for the average adult. This assertion by Tschichold that serif faces are more readable is not fully consistent with Tinker’s finding that sans serif faces are no less readable. However, it should be borne in mind that Tinker’s research was based on much shorter-duration reading tasks than the book, whereas Tschichold was speaking only of typefaces for books. Tinker’s finding that readers preferred serif faces may indicate that research with book-length reading tasks would produce harder evidence.

Beginnings of paragraphs must be indented. The indention – usually one em – is the only sure way to indicate a paragraph.

The gestalt of the written word ties the education and culture of every single human being to the past, whether he is conscious of it or not. “There are always people around offering ever-simpler recipes as the last word in wisdom. At the present it is the ragged-right line, in an unserifed face, and preferably in one size only”.

Beside an indispensable rhythm, the most important thing is distinct, clear and unmistakable form. Tschichold is talking about reading gait here.

Good typesetting is tight; generous letterspacing is difficult to read because the holes disturb the internal linking of the line and thus endanger comprehension of the thought.

Italics should be used for emphasis.

Two constants reign over the proportions of a well-made book: the hand and the eye. A healthy eye is always about two spans away from the book page, and all people hold a book in the same manner.

The books we study should rest at a slant in front of us.

6.10 - Size DOES matter!

Tschichold analyzed page sizes and margins in detail, and says a proportion of 3:4 in page size is fine, but only for quarto books that rest on a table. It is too large for most print, because the size of a double-page spread makes it unwieldy. However, in an electronic book - which has no “facing pages” - this would suggest that the standard screen proportion of 3:4 would work quite well, provided it was used in portrait orientation.

Harmony between page size and type area is achieved when both have the same proportions.

Choice of type size and leading contribute greatly to the beauty of a book. The lines should contain from eight to twelve words; more is a nuisance. Typesetting without leading is a torture for the reader.

Care must be taken to make the spaces between the words in a line optically equal. Wider spacing tends to tear the words of a sentence apart and make comprehension difficult. It results in a page image that is agitated, nervous, flecked with snow. Words in a line are frequently closer to their upper and lower neighbors than to those at the left and right. They lose their significant optical association. Tight typesetting also requires that the space after a period be equal to or narrower than the space between words.

Indents are required at the start of paragraphs. So far no device more economical or even equally good has been found to designate a new group of sentences. Type can only be set without indents if care (i.e. manual intervention) is taken to give the lines at the ends of paragraphs some form of exit. Typesetting without indents makes it difficult for the reader to comprehend what has been printed.

Normal, old-fashioned setting with indents is infinitely better. It simply is not possible to improve upon the old method. It was probably an accidental discovery, but it presents the ideal solution to the problem.

Italic is the right way to emphasize. It is conspicuous because of its tilt, and irritates no more than is necessary for this function.

6.11 - Leading or Interlinear spacing

Leading is of great importance for the legibility, beauty and economy of the composition.

Poor typesetting - set too wide – may be saved if the leading is increased. But even the most substantial leading does not abrogate the rules of good word spacing.

Leading in a piece of work such as a book depends also on the width of the margins. Ample leading needs wide borders in order to make the type area stand out.

Lines over 26 picas almost always demand leading. Longer lines need more because the eye would otherwise find it difficult to pick up the next line.

A fixed and ideal line length for a book does not exist. 21 picas is good if eight to ten-point sizes are used. It is not sufficient for 12 point. Nine centimeters looks abominable when the type size is large, because good line justification becomes almost impossible.

Widows – single words or worse, hyphenated parts of words, which appear as the first line on a page - are unacceptable. The typesetter needs to look at preceding pages – perhaps all the way back to the start of the chapter, where there is generally additional space between chapter heading and text.

Pure white paper is cold, unfriendly and is upsetting because, like snow, it blinds the eye. Lightly tinted paper is superior. This suggests that the screen – which is incapable of displaying snow-white – has some hope. It may even be desirable to use a color tint. It is not only unnecessary, but runs counter to good readability, to try to achieve the binary contrast effect of pure black type on pure white paper.

Tschichold’s assertions are set out in a logical manner. He makes it clear that creating easily-recognizable word-patterns, by attending to the shapes of letters, then to the way in which they are assembled into easily-recognizable words, is at the core of good book production. The remainder is the task of presenting these words to the reader in a smoothly-flowing stream.

The devil is in the details. Some letter pairings in words, for example, do not fit well together unless the pairs are “kerned” or moved closer together to remove some of the white space, which would otherwise tend to break up the word.

Ligatures are another method of grouping letters more closely together to harmonize two or even three-letter combinations: “ff” and “ffl” being two examples.

6.12 - Dowding: FINER POINTS in the spacing and arrangement of TYPE

Another fine logical analysis of the science of typography is given in “Finer Points in the Spacing and Arrangement of Type” by Geoffrey Dowding. Dowding had a long career as typographer to many British publishers; he was also an instructor in typographic design at the London College of Printing for over 20 years.

Most of the book is devoted to the setting of type for continuous reading (i.e. the book).

“Typography consists of detailed manipulation of many variables which may not be immediately obvious, but which in sum add enormously to the appearance and readability of text”
– almost an exact echo of Tschichold.

Even the most carefully-planned design will fall short of perfection unless unremitting attention is paid to these details, “minor canons” which have governed both the printed and written manifestations of the Latin script from the earliest times.

Disturbingly large amounts of white space in the wrong places, i.e. between the words, is the antithesis of good composing and sound workmanship.

Consistently close spacing between words, and after full stops, secures one of the essentials of well-set text matter – a striplike quality of line.

An excessive amount of white space between words makes reading harder.

More interlinear spacing can mitigate effect of carelessly-spaced lines, but a combination of well-spaced lines and properly-spaced words magnifies the beneficial effect of both.

Why does close spacing work?

6.13 - Spacing and recognition

A child learns to read by spelling out words, at first letter by letter, then syllable by syllable and afterwards by reading individual words one at a time. But the eyes of the adult reader take in a group of words at each glance.

Although quite wide spacing is desirable between the words of a child’s book and ample leading is also necessary between the lines (reducing progressively as the child becomes older and more adept), in settings not intended for young children great gaps of white between the words break the eye’s track.

The “color” or degree of blackness of a line is improved tremendously by close word-spacing. A carefully composed text page appears as an orderly series of strips of black separated by horizontal channels of white space.

In slovenly setting the page appears as a gray and muddled pattern of isolated spots, this effect being caused by overly-separated words (the same spottiness is noticeable in most typefaces when read on the computer screen).

The normal, easy, left‑to‑right movement of the eye is slowed down simply because of this separation; further, the short letters and serifs are unable to discharge an important function‑that of keeping the eye on 'the line'. The eye also tends to be confused by a feeling of vertical emphasis, that is, an up & down movement, induced by the relative isolation of the words & consequent insistence of the ascending and descending letters. This movement is further emphasized by those 'rivers' of white which are the inseparable & ugly accompaniments of all carelessly set text matter. The letter‑spacing of words in upper‑ and lower‑case increases the confusion. Of course, in solid, i.e. unleaded settings, such faults, both of word‑ and of letter‑spacing, are especially noticeable.

Any feeling of vertical emphasis is absent in a well‑composed page, the close word‑spacing ensuring that the white space is available for use between the lines where it serves the useful purpose of aiding readability. It is astonishing how much space can be saved depthwise by close spacing in the lines themselves. And in hand‑setting when word‑spacing in a line is close it is more likely to be even throughout the line. In varying the spacing between pairs of words in a too openly spaced line, frequently and often shockingly, the compositor is obviously not intent on securing visually even spacing throughout the line but on justifying it with the least amount of effort in the shortest possible time.

The plea for closer wordspacing in text settings is not something which has been fathered recently by a small company of eccentrics. In the best printing it has been an established practice for over five hundred years, and in the manuscript for many more centuries than that.

In arranging text setting care must be exercised to ensure that the type and the measure are so related that the eye has, firstly, no difficulty in swinging easily to & fro without any suggestion of strain: and secondly, is not hindered in finding the beginning of the following line.

“Other things being equal, the longer the line the greater the excursions of the eyes and the greater the difficulty in passing from one line to the next. Very short lines, on the other hand, demand too frequent a change of direction in the movement of the eyes.”

For what kind of setting are we designing? Is it a large work? How is it to be used? Is it for a Bible, a work of reference, or a novel? If the work is a lectern Bible the reader will be standing & his eyes will be at a considerable distance from the page: each period of reading is likely to be a short one. On the other hand if the work is a pocket dictionary or other book of reference it will either be consulted for brief periods or be pored over; if it is a novel it may be read quickly, perhaps in a single evening: an easily readable measure is therefore imperative.

6.14 - Line Length

Those lines which exceed the normal, i.e. lines of more than nine or ten average words, must be leaded proportionately in order to compensate for the extension.

(Lines in this document are on average 14 words long. But they have additional space between them. This makes them acceptable in a document such as this, intended to be printed on standard letter-sized paper. The lines have also been shortened, by increasing the size of the margins. In a book, this amount of leading would drive up production costs by creating far more pages. This document is also intended to be printed on standard “US letter” paper. If the leading is not increased as the measure is extended there is a risk of “doubling”, i.e. reading the beginning of the same line twice. But some settings to very narrow measures may require less leading thannormal or near normal measures.

Seriffed faces generally, with the exception of those styled 'modern', are undoubtedly easier to read than the sans serifs because the serifs help the normal horizontal movement of the eyes in reading by carrying them along the line. (By “modern”, Dowding is referring to faces such as Bodoni, which have very black, almost bold, letter stems, with highly-contrasted thin serifs). No such guides exist in a sans serif face and unless the lines are impeccably set and well separated by leading there is a distinct tendency to movement in the other direction, i.e. a vertical, or up-and‑down movement.' Sans serif faces require more leading than any other kind of type, except perhaps the Egyptians. Neither is suitable for solid setting. (i.e. unleaded) Modern faces like Bodoni are inclined to dazzle the reader for the reasons already stated especially when printed on coated papers. Faces in this group should always be amply leaded.

6.15 - Dividing words: hyphenation

Consistently close and even spacing cannot be achieved, except in the most unusual circumstances, if the typesetter has resolved never to divide words. Such works would rarely, if ever, be of any typographic distinction.

It is a popularly though erroneously held opinion that close spacing in text setting inevitably multiplies the number of word divisions, for one can have as many, or more, divided words in a careless piece of text composition as in one that is well set. Indeed, the reduction of word‑spacing in a slovenly setting often helps to reunite, and so reduce, the number of divided words. And in ease of reading we tend to gain more by the close spacing of words than we lose in the momentary pauses occasioned at the ends of lines by word‑division: one pauses at the end of each line in any case.

It is infinitely preferable to have a number of break lines succeeding each other than to have widely word‑spaced lines. In a little book (Symbola Heroica) printed at Antwerp by Christopher Plantin in 1583 five successive hyphens are a commonplace, six occur frequently and there is at least one instance of ten. The word‑spacing is very pleasant and there are never any rivers.

Words must be divided according to syllabic or etymological principles. Breaking words merely to the convenience of a full line cannot be justified. There are two places in which divided words prove objectionable. First, in books for the very young. Children who are learning to read are likely to be confused by them. The fact that a hyphen follows the first part of the division means little to a child. Second, no paragraph should end with a divided word. 'Widows" are frowned on by some but much depends on their position on the page: syllabic 'widows' would rightly be condemned wherever they appeared.

6.16 - Tighter setting: importance of ligatures

he term ligature comes from the Latin word ‘ligatura’ which means anything used in binding or tying. In printing, an exact definition of the word would recognize only the actual tie or link between two joined letters, e.g. between the letters ct, st in some fonts. Now, however the term ligature is used less exactly to describe those combinations of either two or three letters which are joined together and cast as one unit, for example ff fi fl ffi ffl, and the compound vowel characters, or vowel-ligatures, ae, oe, known as dipthongs. The ‘f’ ligatures & the vowel ligatures are the ones which are standard to the normal font.

Early founder-printers cut many ligatures for their fonts; today, only certain type designs carry (in roman and italic) great numbers of ligatured letters.

If letters, normally ligatured, are set separately, as they sometimes are, they create the impression that they are on the wrong 'set'. This unpacked and spotty appearance is caused by the excess of white space round them.' From the purely practical point of view ligatures are space savers.

Both Tschichold and Dowding make it clear that the purpose of typography is to create text which presents easily-recognizable word-shapes to the reader in a smooth a manner as possible, leading the reader’s eye from the first word to the last in an unbroken and smooth manner, and that ligatures, because they improve the optical spacing of characters, make words easier to recognize.

In the next section, we analyze this flow and how it is set up.