**3.2 Eye movements during reading**

The basic eye movements relevant to reading and visual search are fixations and saccades. Fixations are periods during which the eye is held relatively still in order to focus on an object [20]. Fixations typically last between 200 and 300 ms but the duration is dependent on the task [20]. For example, when reading in English, the


#### **Table 1.**

*Reading classification according to Halladay [19].*

mean fixation duration is 225–250 ms [21]. Fixation duration refers to the time, in milliseconds, that the eyes dwell on an object. Between fixations, saccades are used to move the eyes to an object of interest. Saccades are high velocity ballistic movements during which visual acuity is suppressed [20]. Saccadic amplitude is a measurement of the length of the saccades and can be measured in terms of visual angle, and refers to the eye span which can be deduced from the jumps (saccades) made by the eyes across the text. When reading text, the saccade length is generally measured in terms of character spaces ([22] as cited in [21]). Average saccade length when reading English is 7–9 characters [20] or 8–9 characters as reported in a later study [21].

Regressions refer to eye movements in the opposite direction of the reading movement. A regression can be a correction when a saccade overshoots the desired text or it can be used to re-read text. Good readers are skilled at using regressions to reposition their eyes where they would like to in order to reinforce something or to gain clarity if they lack understanding, but poor readers are inclined to struggle to use regressions accurately and efficiently and will trace indiscriminately backwards through the text [23]. While the difficulty of the text does influence the number of regressions, it is typical for L1 readers to perform regressions for 10–15% of the time while reading fiction [21].

#### **3.3 Reading behaviour**

Reading can be measured in fixation progress by determining how many characters the reader advances with each saccade [24, 25]. On average, the fixation will fall just left of the word centre [26, 27]—this is referred to as the preferred viewing location [26]. Some studies have found that readers do not fixate on every word while others have found that readers do indeed fixate on almost every word, with readers tending to skip short words [17]. When speed reading or skimming more words are skipped as a natural process [17]. When reading linearly, readers may skip to the next piece of text if they find that the current piece they are reading is no longer giving enough information [28].

Literature suggests that eye movements are useful in detecting reading difficulty and analysing reading behaviour. As readers progress from beginner to skilled (adult) levels, their reading speed [29] and mean saccadic amplitude [30] increase while the number of fixations their eyes make per 100 words, their mean fixation duration and the frequency of their regressions [20] decrease. Reading difficulty is characterised by longer fixation durations, more regressions and shorter saccades [31]. The length of the regression can also highlight whether the reader is experiencing difficulty or not, namely short regressions within a word show lack of understanding of that particular word. Longer regressions show a lack of understanding of the text. Regression percentage is the number of regressions divided by the number of fixations made, expressed as a percentage. It also appears that the number of words per fixation differs according to the difficulty of the text presented. When reading a passage with a difficulty appropriate to the age of the reader, there is an

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difficulty [40].

*Eye Movements during Barking at Print DOI: http://dx.doi.org/10.5772/intechopen.81898*

processing of the word [32].

average of 1.2 words per fixation. If the text is easier than the age level of the reader,

During reading studies, measurements such as first fixation duration, single fixation duration, and gaze duration are often used instead of average fixation duration since readers do not generally only fixate on a word once and words are often skipped during the course of reading the text [21]. It is possible that skipped words may be perceived in the prior fixation and words that are fixated on more than once are likely done so in order to process their meaning [21]. Perceptual span can also be considered a key feature to take into account since this indicates how much the reader can "see" when pausing over a word [21]. English first language (L1) readers appear to be able to perceive a range starting 3–4 characters to the left of the fixation and ending 14–15 characters to the right of the fixation [21]. Vocabulary size has a significant effect on the total time spent on words but not on the initial

The amount of time spent on a word is affected by the ease or difficulty with which the word is processed and other variables [21]. Fixation durations are strongly influenced by the frequency of the word (high frequency words have shorter durations), the predictability of the word being read, the number of meanings the word has, when the meaning of the word was acquired, semantic relations between the word and preceding words and how familiar the word is to the reader (multiple sources as cited in [21]). The length of a word correlates with the likelihood that the reader will fixate on the word again and the likelihood that the reader will skip the word [33]. Words with high frequency are more likely to be skipped than words with low frequency [34] and low frequency words receive more initial processing time than high frequency words [35]. Predictable words are also more likely to be skipped than unpredictable words [36, 37] and they also have a shorter fixation duration [37]. More attention and cognitive effort are required for unfamiliar words than familiar words [32] and while familiar words in L1 and L2 (second language) require similar processing times, unfamiliar words in L1 increase the cognitive load [32]. Unfamiliar words are read slower than familiar words in terms of fixation durations and they are read "more times"—in other words regressions to unfamiliar words are more common than to familiar words [35]. Similarly, when reading in L2, unfamiliar words have a higher fixation duration than familiar words and are visited more than familiar words [38]. However, in this instance the initial processing time between

then the number of words per fixation has a higher average [17].

familiar and unfamiliar words is not significantly different [38].

**3.4 Behaviour in different types of reading**

Eye movement measurements can also be evaluated on the first and second pass—the first pass being the first time the word is read and the second pass being the subsequent time the word/piece is read if the reader regresses to that word/ piece [39]. First fixation duration, single fixation duration and the likelihood that the word will be refixated are indicators of the difficulty of the word experienced during the initial reading while gaze duration is an indicator of the difficulty experienced in identifying the word [40]. Second pass duration indicates late measures of word difficulty and total fixation time can be used to measure comprehension

The measurements discussed in the previous section were presumably measured

For instance, since reading behaviour is coupled with cognitive processing, it stands to reason that eye movements can indicate when attention is low. Fixation

for readers reading in English, which in all likelihood was their first language. Reading in a second or third language may be characterised by different behaviour

and there are different types of reading which can be conducted.

#### *Eye Movements during Barking at Print DOI: http://dx.doi.org/10.5772/intechopen.81898*

*Visual Impairment and Blindness - What We Know and What We Have to Know*

mean fixation duration is 225–250 ms [21]. Fixation duration refers to the time, in milliseconds, that the eyes dwell on an object. Between fixations, saccades are used to move the eyes to an object of interest. Saccades are high velocity ballistic movements during which visual acuity is suppressed [20]. Saccadic amplitude is a measurement of the length of the saccades and can be measured in terms of visual angle, and refers to the eye span which can be deduced from the jumps (saccades) made by the eyes across the text. When reading text, the saccade length is generally measured in terms of character spaces ([22] as cited in [21]). Average saccade length when reading English is 7–9 characters [20] or 8–9 characters as reported in a later

Independent level (level 1) 99 90 Instructional level (level 2) 95–99 75–89 Frustration level (level 3) ≤90 ≤50

**Decoding accuracy (%) Comprehension (%)**

Regressions refer to eye movements in the opposite direction of the reading movement. A regression can be a correction when a saccade overshoots the desired text or it can be used to re-read text. Good readers are skilled at using regressions to reposition their eyes where they would like to in order to reinforce something or to gain clarity if they lack understanding, but poor readers are inclined to struggle to use regressions accurately and efficiently and will trace indiscriminately backwards through the text [23]. While the difficulty of the text does influence the number of regressions, it is typical for L1 readers to perform regressions for 10–15% of the time while reading

Reading can be measured in fixation progress by determining how many characters the reader advances with each saccade [24, 25]. On average, the fixation will fall just left of the word centre [26, 27]—this is referred to as the preferred viewing location [26]. Some studies have found that readers do not fixate on every word while others have found that readers do indeed fixate on almost every word, with readers tending to skip short words [17]. When speed reading or skimming more words are skipped as a natural process [17]. When reading linearly, readers may skip to the next piece of text if they find that the current piece they are reading is no

Literature suggests that eye movements are useful in detecting reading difficulty

and analysing reading behaviour. As readers progress from beginner to skilled (adult) levels, their reading speed [29] and mean saccadic amplitude [30] increase while the number of fixations their eyes make per 100 words, their mean fixation duration and the frequency of their regressions [20] decrease. Reading difficulty is characterised by longer fixation durations, more regressions and shorter saccades [31]. The length of the regression can also highlight whether the reader is experiencing difficulty or not, namely short regressions within a word show lack of understanding of that particular word. Longer regressions show a lack of understanding of the text. Regression percentage is the number of regressions divided by the number of fixations made, expressed as a percentage. It also appears that the number of words per fixation differs according to the difficulty of the text presented. When reading a passage with a difficulty appropriate to the age of the reader, there is an

**362**

study [21].

**Table 1.**

*Reading classification according to Halladay [19].*

fiction [21].

**3.3 Reading behaviour**

longer giving enough information [28].

average of 1.2 words per fixation. If the text is easier than the age level of the reader, then the number of words per fixation has a higher average [17].

During reading studies, measurements such as first fixation duration, single fixation duration, and gaze duration are often used instead of average fixation duration since readers do not generally only fixate on a word once and words are often skipped during the course of reading the text [21]. It is possible that skipped words may be perceived in the prior fixation and words that are fixated on more than once are likely done so in order to process their meaning [21]. Perceptual span can also be considered a key feature to take into account since this indicates how much the reader can "see" when pausing over a word [21]. English first language (L1) readers appear to be able to perceive a range starting 3–4 characters to the left of the fixation and ending 14–15 characters to the right of the fixation [21]. Vocabulary size has a significant effect on the total time spent on words but not on the initial processing of the word [32].

The amount of time spent on a word is affected by the ease or difficulty with which the word is processed and other variables [21]. Fixation durations are strongly influenced by the frequency of the word (high frequency words have shorter durations), the predictability of the word being read, the number of meanings the word has, when the meaning of the word was acquired, semantic relations between the word and preceding words and how familiar the word is to the reader (multiple sources as cited in [21]). The length of a word correlates with the likelihood that the reader will fixate on the word again and the likelihood that the reader will skip the word [33]. Words with high frequency are more likely to be skipped than words with low frequency [34] and low frequency words receive more initial processing time than high frequency words [35]. Predictable words are also more likely to be skipped than unpredictable words [36, 37] and they also have a shorter fixation duration [37]. More attention and cognitive effort are required for unfamiliar words than familiar words [32] and while familiar words in L1 and L2 (second language) require similar processing times, unfamiliar words in L1 increase the cognitive load [32]. Unfamiliar words are read slower than familiar words in terms of fixation durations and they are read "more times"—in other words regressions to unfamiliar words are more common than to familiar words [35]. Similarly, when reading in L2, unfamiliar words have a higher fixation duration than familiar words and are visited more than familiar words [38]. However, in this instance the initial processing time between familiar and unfamiliar words is not significantly different [38].

Eye movement measurements can also be evaluated on the first and second pass—the first pass being the first time the word is read and the second pass being the subsequent time the word/piece is read if the reader regresses to that word/ piece [39]. First fixation duration, single fixation duration and the likelihood that the word will be refixated are indicators of the difficulty of the word experienced during the initial reading while gaze duration is an indicator of the difficulty experienced in identifying the word [40]. Second pass duration indicates late measures of word difficulty and total fixation time can be used to measure comprehension difficulty [40].

#### **3.4 Behaviour in different types of reading**

The measurements discussed in the previous section were presumably measured for readers reading in English, which in all likelihood was their first language. Reading in a second or third language may be characterised by different behaviour and there are different types of reading which can be conducted.

For instance, since reading behaviour is coupled with cognitive processing, it stands to reason that eye movements can indicate when attention is low. Fixation durations are indicative of the amount of processing which is occurring, with longer fixations on words that require more processing [17]. Words which require more processing are infrequent words, while longer fixations are seen when making inferences at the end of a sentence and when integrating information from important clauses [17]. As a means to detect mindless wandering, or low attention while reading, eye movement behaviour at the end of phrases or sentences can be used—the natural slowing down in reading which occurs in order to integrate the words does not occur when attention is low [41]. Additionally, the variability in fixation durations caused by word length and frequency is lower when the reader is not paying attention [41]. Hence, when the mind of the reader wanders, there are short fixations on low frequency words and long fixations on high frequency words [41]. Fixations are also fewer and longer and eye behaviour is more erratic when the mind wanders [42]. First fixation durations, total gaze duration and total viewing time are shorter for normal reading than for wandering [42]. Additionally, when the mind wanders, readers are less likely to make fixations and regressions on text and more likely to fixate on areas other than the text [42]. The number of saccades and fixations drops when the mind wanders and there are less and shorter within-word regressions [43].

When scanning transformed text as opposed to reading, fixations are longer and saccades are shorter [15]. In this instance, transformed text refers to the practice of replacing all alphabetic characters with the letter z but preserving casing and punctuation among other characteristics [15]. Participants were requested to pretend to read the transformed text [15] in order to simulate scanning. In contrast, skimming normal text for proofreading is characterised by shorter fixations, and longer saccades than when reading text for understanding [21]. Readers also tend to read the start of the text more thoroughly than the second half and readers first skim the entire text before reading it [28]. When reading in a second language (L2), reading times are longer and readers exhibit more fixations, shorter saccades and less word skipping than when they read in their first language (L1) [44]. Furthermore, L2 readers of Afrikaans text required an average of one fixation per syllable [45]. Fixation durations for L2 readers were longer, averaging 313 and 331 ms for an easy and difficult text respectively [45]. The increased fixation times in L2 could be attributed to the fact that L2 processing requires more cognitive load than L1 [32]. One of the purposes of this research is to understand whether the reading ability of South African township learners can meaningfully be classified using the guidelines developed in publications such as those referred to above.

In a comprehensive study eye movement behaviour was investigated for the different types of reading. This study will be discussed in greater depth for the purposes of this chapter. Regular reading, or reading for comprehension, is defined as reading a piece of text as one would normally read [46] as cited [47]. Thorough reading is reading to learn and is used to read text in a manner which will allow them to learn the content, perhaps in order to write a test about the content [48] as cited in [47]. Skimming, also known as reading for gist, means the reader must read the text as quickly as possible while still trying to understand the content [46] as cited in [47] and spell checking is the type of reading which is conducted in order to detect spelling errors in a text [49].

Thorough reading exhibits longer reading times and more rereading which results in higher comprehension scores [47]. When skimming, participants exhibit longer saccades, short fixations and skip more words [47]. Additionally, the total reading time is shorter and comprehension is lower [47]. When reading in order to achieve spell checking, saccades are short, fixation durations are long and fewer words are skipped [47]. Comprehension scores are lower and total reading times are longer [47]. Overall thorough reading was less uniform than regular reading, skimming was faster and more uniform and spell checking was slower and more uniform [47].

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*Eye Movements during Barking at Print DOI: http://dx.doi.org/10.5772/intechopen.81898*

more regressions.

**4. Methodology**

tion correctly.

the sample for this study.

increase in first pass metrics.

**4.1 Sample and data collection**

**3.5 Summary of reading behaviour indicators**

In summary, reading difficulty is characterised by long fixations, higher incidence of regressions and shorter saccades. Similarly, scanning transformed text results in longer fixations and shorter saccades but skimming results in shorter fixations and longer saccades. When reading in a second language, readers exhibit more fixations, shorter saccades and less word skipping and unfamiliar words cause higher fixation durations and are visited more. Unfamiliar words in L1 require more cognitive processing and hence they are read slower and cause

Thorough reading has more visits on words and more vertical saccades and has a pattern similar to regular reading. When skimming, fixation durations are much shorter, while saccades are much larger and there are fewer regressions. In contrast, spell checking shows an increase in fixation duration and smaller saccades and an

The 67 grade 8 and 9 learners who form the sample for this study attended two schools in densely populated areas of extreme poverty and high unemployment, 50 km from the nearest town, Bloemfontein, in South Africa. The sample was relatively academically strong for the context, since 50 of the learners had been identified, by their teachers, as being among the strongest in mathematics and natural sciences in their class, with the others being randomly chosen to increase the ability range. Each participant read a comprehension text about lighting, with a Flesch-Kincaid reading difficulty level [50] of grade 9, and answered four multiple choice questions about this text, individually, on a computer fitted with a Tobii TX300 eye-tracker. Tobii Studio 3.4.5, installed on the computer, was used for data extraction, including the generation of a screen-capture video showing eye-movements and mouse clicks, for each learner. The data collected for this article were obtained as the learners engaged with two screens. Screen 1 consisted of 5 lines of text about lighting, with an illustrative diagram below the text. Screen 2 was divided into two with the left-hand half being a repeat of the first screen and the right-hand half displaying the multiple choice questions one at a time. The learner progressed through the four questions once he/she had answered a ques-

Consistent with Pretorius and Spaull's [10] statistics about poor South African learners' reading abilities, 2 of the original 69 learners in this relatively strong sample did not even show evidence of being able to decode the text they were given to read since they moved their eyes randomly around the screen for a while before claiming they had finished reading. These 2 learners were therefore excluded from this study. The remaining 67 learners' eyes did track the text systematically, at least for parts of the text, suggesting, to the extent to which this is possible from eye tracking data, that they were engaging in text decoding, and so were admitted into

These learners were divided into the categories shown in **Table 2**, which is based on the learners' reading behaviour and comprehension scores, informed both by a qualitative analysis of the learners' eye movements during the question answering process and by the scores the software displayed in response to their choices. Guessing was inferred if the learner did not read sufficient text in the question or
