Reply To: DST-S Backwards Digit Span Test

[Jacqueline]

Hi,
I think it is important to differentiate between working memory and verbal processing- they are not the same.
The Digits backward test measures working memory: the ability to hold information in short term memory and simultaneously work with that information before it is lost or forgotten.
Phonological memory (CTOPP2 digits forward and digit forwards) specifically measures the capacity to hold spoken language in short term memory. Neither of the above really assess verbal processing.
Verbal processing is about the ability to process the sounds of language (rather than just remember them), so to link meaning with the sounds of language. It is commonly measured with the ctopp2 rapid naming subtests, made up of digit naming and letter naming. Here. The individual must read the page of numbers/letters as quickly and as accurately as possible. To do this efficiently requires good verbal processing as one must be able to retrieve the verbal response from long term memory in response to a visual stimulus(the number or letter).
In all cases the composite score is most reliable and so it’s not a good idea to split the scores- or just look at performance on one subtest.
However, when assessing working memory it is true that the backwards test assess this specifically rather than the forwards tests, so sometimes a clear discrepancy can be seen here!!
Hope this makes sense?!