Comunicación visual

Inadequate phonological awareness has been considered to be one of the most prominent characteristics of dyslexia (Goswami, 2002; Snowling, 2000). The term ‘phonological awareness’ refers to the conceptual understanding and the explicit awareness that spoken words consist of individual speech sounds (phonemes) and combinations of speech sounds (syllables, onset- rime units).

Bishop and Adams (1990) proposed the critical age hypothesis. According to this, the extent to which a child is vulnerable to reading failure depends on the level of his/her phonological processing skills at the stage when children are expected to be able to learn to read.

Regarding the spoken features of a language, the operational definition of phonological awareness refers on the ability to divide a spoken stream into distinct sound units (e.g. syllables), to classify words based on their identical sound elements (e.g. onsets and rimes), to delete a phoneme from a syllable or to blend individual phonemes into a syllable. In other words, deficient phonological awareness can be demonstrated at different phonological “grain sizes,” such as syllables, onset-rhymes or phonemes (Goswami & Bryant, 1990; Ziegler & Goswami, 2005).

Traditionally, phonological awareness has been examined through several ways. Different tasks may be used to test different levels of phonological awareness and researchers should consider the age and learning experiences of participants when selecting their tasks.

Examples of phonological awareness tasks are the following:

 Tapping to repeat a word spoken by the examiner and count the number of syllables or phonemes by tapping with a small dowel

(Liberman, Shankweiler, Fischer, & Carter, 1974).

 Counting to tell the number of syllables or phonemes in a word by giving coins (Treiman & Baron, 1981).

 Same-different to hear two words presented together in time and to tell whether the two words shared the same syllable, onset-rhyme or phoneme (Adams, 1994).

 Deleting the first or the last "sound" of each word and to answer what is left. The sound can be instructed as a syllable or phoneme (Bruce, 1964; Stanovich, Cunningham & Cramer, 1984).

 Blending to integrate individual syllables or phonemes into words (Anthony et al., 2002; Fox & Routh, 1975).

 Oddity to listen to three or four mono-syllables and identify the odd one out, with different first, middle or final sounds (Bradley & Bryant, 1978; Bradley & Bryant, 1983).

 Segmentation to tell what individual sound elements were heard in a word (Fox & Routh, 1975).

Phonological awareness, phonological memory, and speed of access to production of phonological codes have been frequently grouped as a phonological construct (Wagner & Torgesen, 1987). Research on alphabetical languages has indicated that phonological awareness is usually the best causal predictor of reading success (Adams, 1994; Bradley & Bryant, 1983). In a three-year longitudinal investigation, Torgesen, Wagner, and Rashotte (1994) found significant correlations between all the measures of phonological performance in 244 kindergarten children and alphabetic reading skills at both 1st and 2nd grade, when IQ, general verbal ability and pre-reading skill (i.e., knowledge of letters) were controlled. However, only phonological awareness appeared as a unique predictor of word-reading development in a structural equation model.

MacDonald and Cornwall (1995) investigated the long term effect of early phonological awareness on subsequent word identification and spelling in

English. Twenty four kindergarten children participated in the study and were tested later again when they were 17 years old. Their early phonological awareness at kindergarten significantly contributed to later reading and spelling skills at high school. It showed that within the domain of phonology, longitudinal and cross-sectional studies have repeatedly isolated phonological awareness as the most significant predictor of reading development (Lonigan, Burgess, & Anthony, 2000).

The significant role of phonological sensitivity in predicting reading ability seems to be universal across languages (Lafrance & Gottardo, 2005; Chow, McBride-Chang, & Burgess, 2005) and across development (Molfese, Molfese, & Modglin, 2001, Ziegler & Goswami, 2005).

Tunmer and Hoover’s (1992) suggest that phonological awareness is essential for the recoding process between phonemes and graphemes.

Previous findings consistently prove that:

(a) During the decoding process, skilled readers deal with phonological information better than less-skilled readers.

(b) Early performance of phonological awareness can predict subsequent reading achievement at school, even when preschool verbal and letter knowledge are controlled.

(c) Phonological awareness training significantly improves reading performance and development.

(d) Phonological awareness influences reading performance through the mediation of phonological recoding skill.

Therefore, phonological awareness affects the development of single word reading and decoding through its relationship with phonological recoding. Empirical evidence supports the role of phonological awareness as a critical developmental factor in reading acquisition.

Impaired phonological awareness, arising from poorly-specified phonological representations of spoken sounds, hampers children’s development of reading acquisition, no matter what writing system has been used.

For instance, using reading-age (RA-match) match designs, Bradley and Bryant (1978) employed oddity tasks at the onset-rhyme level to identify the poor phonological awareness of English “backward readers.” Compared with typically developing children, the dyslexic children performed significantly worse in both onset-rhyme awareness and rhyme production. Similar findings have been reported by many other studies, and even in different languages (English: Bowey, Cain & Ryan, 1992; German: Landerl, Wimmer & Frith, 1997; Chinese: Ho, Law & Ng, 2000; Korean: Kim & Davis, 2004; Japanese: Seki, Kassai, Uchiyama, & Koeda, 2008). Also there are unexpected symmetries in the left versus the right hemispheres of those whose brains were studied (Galaburda, Sherman, Rosen, Aboitiz, & Geschwind, 1985; Humphreys, Kaufmann, & Galaburda, 1990). This area of the left hemisphere supports language functions that may relate to reading problems. A second set of research findings involves small, focal anomalies that appear when microscopic evaluations of the brain are performed. These anomalies were found to be more common in the left hemispheres of individuals who were diagnosed as dyslexic. Microscopic tests of subcortical structures have also indicated differences in the thalamus that may be related to visual processing (Livingstone et al., 1991).

For the planum temporale, several studies (e.g. Hynd, Semrud-Clikeman, Lorys, Novey, & Eliopulos, 1990; Larsen, Høien, Lundberg, & Odegarrd, 1990) report symmetry as well as reversals in the expected pattern of asymmetry (Hynd et al., 1990). However, they did not prove any relationships of size or symmetry of the planum temporale in dyslexia (Rumsey et al., 1997; Schultz et al., 1994).

Leonard et al. (1996) proved that higher degrees of asymmetry of the temporal lobes were associated with better reading performance, regardless of whether the child had RD. Other studies report that the temporo-parietal brain areas are smaller (Duara et al., 1991; Kushch et al., 1993), or not different in those with or without RD (Hynd et al., 1990; Jernigan, Hesselink, Sowell, & Tallal, 1991).

Other research studies that measured the corpus callosum found either differences (Duara et al., 1991; Hynd et al., 1990) or no differences in its size (Larsen et al., 1990; Schultz et al., 1994) between groups of dyslexic individuals and typically developing ones.