Reading Derived Words by Italian Children With and Without Dyslexia: The Effect of Root Length

Abstract

Children with dyslexia are extremely slow at reading long words but they are faster with stimuli composed of roots and derivational suffixes (e.g., CASSIERE, ‘cashier’) than stimuli not decomposable in morphemes (e.g., CAMMELLO, ‘camel’). The present study assessed whether root length modulates children’s morphological processing. For typically developing readers, root activation was expected to be higher for longer than shorter roots because longer roots are more informative access units than shorter ones. By contrast, readers with dyslexia were not expected to be facilitated by longer roots because these roots might exceed dyslexics’ processing capacities. Two groups of Italian 6th graders, with and without dyslexia, read aloud low-frequency derived words, with familiar roots and suffixes. Word reaction times (RTs) and mispronunciations were recorded. Linear mixed-effects regression analyses on RTs showed the inhibitory effect of word length and the facilitating effect of root frequency for both children with and without dyslexia. Root length predicted RTs of typically developing readers only, with faster RTs for longer roots, over and above the inhibitory effect of word length. Furthermore, typically developing children had faster RTs on words with more frequent suffixes while children with dyslexia were faster when roots had a small family size. Generalized linear regression analyses on accuracy showed facilitating effects of word frequency and suffix frequency, for both groups. The large word length effect on latencies confirmed laborious whole-word processing in children when reading low-frequency derived words. The absence of a word frequency effect along with the facilitating effect of root frequency indicated morphemic processing in all readers. The reversed root length effect in typically developing readers pointed to a stronger activation for longer roots in keeping with the idea that these represent particularly informative units for word decoding. For readers with dyslexia the facilitating effect of root frequency (not modulated by root length) confirmed a pervasive benefit of root activation while the lack of root length modulation indicated that the longest roots were for them too large units to be processed within a single fixation.

Perceptual salience of derivational suffixes in visual word recognition

“…Our results show that words with high suffix salience (i.e., longer suffixes and shorter stems) requires more fixation time than words with low suffix salience (i.e., shorter suffixes and longer stems). So, the paper by Burani et al , () and ours are showing two relevant aspects of complex word processing. The first one is that by increasing the perceptual salience of suffixes readers become more sensitive to them and the second one is that the longer the stem – and the shorter the suffix‐ the faster the processing in the first stages.…”

“…Our assumption goes in the same direction although it points further because it is that by increasing the perceptual salience of suffixes readers become more sensitive to them and therefore compositional route is favored in comparison to the direct route – or in terms of Burani, Marcolini Traficante and Zoccollotti (), the longer the morphemic constituent is, the more informative this reading unit (see also Kuperman et al , , for similar discussion about the interplay between suffix length and word frequency). An interesting issue to highlight from the paper by Burani et al , () is that they found similar results to ours, despite focusing on stem length. Indeed they found a facilitative effect by which words with longer stems required less time to be read than words with shorter ones.…”

The Deployment of Young Readers´ Visual Attention across Orthographic Strings: The Influence of Stems and Suffixes

“…The key finding of the present study is that while the presence of stems and suffixes did not provide an overall boost in letter detection in our visual one-back paradigm, the specific knowledge about stems and suffixes during childhood might slightly modulate letter coding strategies through the deployment of visual attention across letter strings (also see: Burani, Marcolini, Traficante, & Zoccolotti, 2018;Law et al, 2018). This modulation might be partly attributed to the frequency with which these orthographic units are encountered in written language.…”

Dyslexia: Causes and Concomitant Impairments

“…The visual attention span hypothesis assumes that the ability to process multiple letters that make up a word is impaired in children with dyslexia and that this is due to a reduced visual attention span [ 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 , 96 , 97 , 98 , 99 , 100 , 101 , 102 , 103 , 104 , 105 , 106 , 107 , 108 ]. Whether this impairment is due to a reduced attention span or any other visual deficit depends on what is understood by ”attention span“.…”