Figure 1.
A cohort of 103 participants with dyslexia were assigned to four groups (I…IV), and each read two test Forms (A, B) from the Gates-MacGinitie Reading Tests [30] using paper or iPod, in a design balanced for order of device and form. The process was repeated at two Levels (7, 10).
Table 1.
Demographic statistics and reading measures of participants.
Figure 2.
Sample stimuli comparing paper and iPod conditions.
In the paper condition students read passages from the Gates-MacGinitie Reading Tests and answered multiple choice questions as shown. In the iPod condition the reading passage was displayed on the iPod (scrolled vertically using a finger on the touchscreen) and questions were answered on paper, as in the paper condition, except that the text passage was not displayed. Following standard protocol for this test, students were allowed to re-examine the text when answering questions, in both conditions.
Table 2.
Analysis of Reading Comprehension Score.
Figure 3.
Shape of the interaction of method and VA Span for comprehension.
A significant interaction of method*VA Span was observed when comprehension was taken as the dependent variable. Here, the mean comprehension score is shown as a function of VA Span, the number of letters correctly identified on a six letter global report paradigm. The iPod is indicated in red, and paper is indicated in blue. The figure shows that those with low scores on the global report task comprehend better when reading on the iPod while the reverse is true for those with high scores. (The colored shading indicates a confidence interval for this interaction, defined by a +/−1-sigma within-subjects standard error of the mean [68]).
Figure 4.
Shape of interaction of method and PD for reading speed.
A significant interaction of method*PD was observed when reading speed was taken as the dependent variable. Here, the speed is shown as a function of PD, a measure of phonemic decoding. The interaction indicates that those with poor phonemic decoding scores perform better when reading on the iPod, while the reverse is the case for those with strong phonemic decoding scores. (Coloring, etc., as in Fig. 3.)
Table 3.
Analysis of Reading speed.
Figure 5.
A proposed explanation: Short lines guide attention to the uncrowded span.
(A) Crowding is easily demonstrated. Fixating on the red line, most of the characters in the word “visual” can be identified, while those in the adjacent word “covert” (say, the letter “r”), viewed peripherally, are difficult to discern. However, when peripheral letters are viewed in isolation (the “r” to the right), the uncluttered text is more readily identified. This peripheral interaction phenomenon is referred to as crowding [67]. (B) Crowding increases with angle from fixation, as suggested schematically by the stippling. Given this, only the word closest to fixation (“visual”) falls within the “uncrowded span” [10] that is easily read. (C) Therefore, as the gaze shifts during reading, attention (here suggested using a radial blur) must track the uncrowded span as fixations advance. (D) However, for those with attention deficits, attention shifting is sluggish [53], and we suggest that this causes attention to be slow to disengage from the previously fixated word (“covert”) as the gaze advances. Attention is therefore over-emphasized in the periphery (left of fixation), where words are subject to crowding and difficult to discern. We propose that these factors conspire to make reading difficult in some people with attentional forms of dyslexia. (E) Short lines ameliorate such deficits by guiding attention to the uncrowded span, while minimizing confusion caused by the presence of crowded text to the left of fixation.