We have spent more than 20 years following and measuring the reading performance of thousands of children. During that time we have observed, measured and eventually explained the different reading patterns of children with good phonic skills and those with habituated whole word guessing habits.

Among the more important findings has been the understanding of the relationship between VAS LEVELS and reading accuracy. In phonic processing there is only a loose relationship between VAS and reading ability; children with good phonic skills can become good readers and spellers almost regardless of their VAS level.

But we observed that the whole word, guess-dependent children needed a higher VAS if they were to guess words correctly…the higher the VAS the better they were at guessing. We noted that for short words the end letters and the letters with limbs were selected as a basis for whole word guessing but that in longer words the emphasis shifted towards the letters at the beginning of words. We found for example that an infant with a VAS level of 3 could usually read 3,4 or 5 letter words but that accuracy seemed to falter with anything longer. From those observations we developed the rule of thumb that VAS +2 identified a potential accuracy-threshold for guess-dependent infants.

We called the VAS+2 rule 'The VAS Ceiling'; it allows teachers to predict the approximate word length that can be confidently learned.

Of course it is only an approximation because some words are distinctive and therefore easier to guess. For example an infant with a VAS of 3 may look at the word ‘Elephant’ and correctly guess the word because the child knows no other long word that will fit that pattern. But if you showed the child the 7 letter word ‘Elegant’ he is likely to misread it as ‘Elephant’ because you have overstepped his VAS Level 3 + 2 =5 VAS Ceiling.

This immediately raised our concerns because we knew that VAS levels seldom exceed level 5 even in adults. If the rule-of-thumb formula (VAS + 2 = guessable word length) was correct then we predicted that guess-dependent children with a high VAS of 5 should struggle with simple 3 syllabic words because such words have at least 9 letters and this exceeds the formula VAS(5)+2=7 letter words. A child with a low VAS of 3 will reach their VAS ceiling at five letter words: e.g. VAS (3) + 2 = 5

We also observed that once guessing habits were established they tended to persist. We therefore predicted that accuracy in reading simple but long 3 syllabic words should be an ongoing problem for guess-dependent children.

In order to establish the prevalence and effects of word guessing we studied 911 Failing readers.

We looked at their errors when reading simple three syllabic words; words that would pose no problems to an infant with good phonic skills and found, just as we had predicted, that 94% made repeated errors on 3 syllabic words at age 9 and 75% still exhibited the same inaccuracies at the end of primary school.

We also found similar trends in 676 Average readers and 616 Superior readers along with widespread evidence that the inaccuracies were associated with habituated word-guessing.

There is however another problem: whole word guessing involves three stages:
Stage 1. the student pays attention to some letters (the number of letters is determined by their VAS level);
Stage 2. they then transform those letters to form a pattern
Stage 3.
they search in their memory for a word that matches that pattern. The problem arises if the student has never seen or heard the word before (for example Aboriginal words such as Eromanga, Kununurra). The child then cannot recognise the word.

By grade 4 the text books become less controlled for word length and there are increasing numbers of these unfamiliar words. The guess-dependent infant therefore has problems with the increasing number of long words particularly if unfamiliar. They also confuse visually similar words such as insect, inspect, instruct etc.

The guess-dependent child trying to word-guess with a VAS of 2 is therefore doomed to failure because his VAS Ceiling is VAS (2) + 2 means that 4 letter words is his guessing limit. At VAS level 3 words up to 5 letter length is therefore considered to be the minimum VAS level for whole word guessing

The VAS Development Graph.
The two dotted lines show the development of Average VAS (black dot) and Low VAS (red dots).

Interpreting the Average VAS line.
A) The black dotted 'Average VAS' line at the age of 6 shows a VAS of about 1.7.
B) The black dotted line crosses the VAS 3 line (the bold horizontal line at VAS level 3) at about the age of 7.6
C) The curve gradually flattens until it hits its ceiling at about VAS 4.2

Teaching tips for the child with AVERAGE VAS.
Whole word processing (sight words) is going to be unreliable until 7.6 years of age, the age when VAS level 3 is reached. Your emphasis must therefore be on phonic skills.
The maximum VAS level is 4.2 and this was attained about the age of 12. The rule of thumb (VAS+2 = guessable word length) is 4.2+2= 6.2; in other words, if you make this child guess-dependent, you can expect ongoing inaccurate guessing for words 7 letters long.

Interpreting the Low VAS line.
The red dotted line cross the VAS 3 line at the age of 9 years 7 months.
The red dotted VAS curve flattens out about the age of 12 with a VAS of 3.2

Teaching tips for the child with Low VAS
This child will struggle to develop sight words until the of 9 years 7 months. If you encourage learning to read by whole word guessing, this child will fail as a direct consequence of inappropriate teaching.
He must therefore receive systematic phonics from the outset.
The 3.2 ceiling reached by the age of 12 means that the 3.2+2=5.2 rule of thumb will make a guess-dependent child inaccurate for 6 letter words.


The child with a low VAS is particularly vulnerable to the damage that can be caused by early guess-dependence.

Those infants who begin learning to read with a low VAS will probably always have a lower VAS than the general population (refer to the graph). If they have phonic skills this matters little, as they can move easily from the early blending of sounds into the blending of syllables and thus read words of any length. Their phonic skills thus allows them to break through the VAS ceiling that would otherwise handicap their reading.
Those who are deprived of early and reliable phonic skills, be they low VAS or high VAS, are denied the opportunity to break the VAS barrier.