Segments is test of general phonological processing abilities requiring deletion of segments of words. For example, ‘butterfly’ without the syllable ‘ter’ would be pronounced ‘buh´fly’ (strictly: not ‘but´fly’, unless one was using knowledge that the word was spelt with a double ‘t’, rather than relying on the sounds of the syllables).

As children learn to talk they develop increasingly sophisticated cognitive representations for phonological aspects of speech. They become aware that words can be segmented into syllables (e.g. that ‘wigwam’ is composed of ‘wig’ and ‘wam’), and that different words can contain similar elements (i.e. similar onsets like w-ig and w-am, or similar rimes like w-ig and pig). The importance of this phonological awareness for early literacy development has been very well demonstrated in research carried out all over the world in the past twenty years (for reviews and discussion of issues, see Snowling, 1995; Goswami, 1994, 1999, 2001; Goswami and Bryant, 1990; Rack, 1994; Savage, 2001). Phonological awareness in very young students is often assessed by means of an ‘oddity task’ in which the student has to pick out the one which is different from of list of similar sounding words, e.g. ‘mop, hop, tap, lop’; ‘ham, tap, had, hat’ (Bradley and Bryant, 1983; Bradley, 1980). However, phonological deletion tasks, such as Segments, have been found to be more sensitive measures for use with older students (Snowling, 2000).

Dyslexic students are known generally to have poor phonological skills (Rack, Snowling and Olson, 1992; Holligan and Johnston, 1988). In the phonological deficit model of dyslexia (Hulme and Snowling, 1991; Snowling, 1995, 2000) it has been hypothesised that the status of students’ underlying phonological representations determines the ease with which they learn to read, and that the poorly developed phonological representations of dyslexic students are the fundamental cause of their literacy difficulties. In the CoPS research the Rhymes test was found to be a highly significant predictor of later literacy skill (Singleton, Thomas and Horne, 2000).

There is good evidence that individuals of all ages with dyslexia have persistent difficulties with phonological deletion tasks (Bruck, 1990, 1992; Gottardo, Siegel and Stanovich, 1997; Snowling, 2000). Low performance on Segments is therefore a good indication of dyslexia. However, like Nonwords, teachers should be aware that students with hearing problems may also have low scores on Segments. By inspecting the data pages for the module, the assessor can examine the student’s results in detail. This will help to determine whether the problem is mainly one of hearing – in which case errors will usually be scattered throughout the test – rather than phonological processing, in which case errors will tend to increase as the test gets more difficult.