Digit span versus letter number sequencing

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miriam
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Digit span versus letter number sequencing

Post by miriam »

Any thoughts on what could explain one being much higher than the other? They both involve sequencing and most people probably use auditory memory to manipulate the sequence, but what if there was a 4+ point discrepancy?

Just pondering on the detail of an assessment I've done where receptive and expressive language is clearly an area of difficulty but visuo-spatial skills and processing speed are quite well preserved.
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Re: Digit span versus letter number sequencing

Post by Butterfly22 »

I have encountered a similar pattern several times in the past so have wondered about this too, but its not my area of expertise by any means! You may have already thought of this, but my thinking has been that maybe the LNS is a more complex task because of needing to work with and switch between using two kinds of information (letters and numbers) vs just using numbers in the DS? Did you get a sense of whether the person understood the instructions and could hold all the parts of them in mind throughout? There's a few operations that need to be performed and maybe the receptive language skills were a particular barrier to taking all of this on board? Although that wouldn't make sense as a hypothesis if it could equally apply to other subtests... Others with more knowledge may have better suggestions.
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Re: Digit span versus letter number sequencing

Post by miriam »

I'd have thought likewise, which is why it is strange that all the siblings in this assessment have significantly better scores at LNS than DS...
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Re: Digit span versus letter number sequencing

Post by Gilly »

Digit span is primarily a working memory task, however letter number sequencing, as butterfly said, is much more complex - requiring increased mental flexibility and ability to not only hold/repeat information, but to hold it, manipulate it and then repeat, so perhaps theres a possibility that the receptive/expressive language difficulties are not "pushed" as hard on the more straightforward digit span measures (which is just to list back a series of letters) but that the extra cognitive load on LNS shows that difficulty more evidently? Did they perform worse on digit backwards (since that requires a bit more mental maniulation?)

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Re: Digit span versus letter number sequencing

Post by Butterfly22 »

Here's a link which may be of help - click on the first search result (google books preview of WISC-IV Advanced Clinical Interpretation, p256):

https://www.google.co.uk/search?q=lette ... digit+span
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Re: Digit span versus letter number sequencing

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Really interesting.. it's very unusual to do signicantly better at LNS than DS.. As Gilly said, was there any discrepancy between DSF and DSB?

If the DSB score is quite a bit lower then you might find some explanation in the fact that DSB relies more strongly on verbatim memory encoding than letter number sequencing..

Broadly the LNS subtest also allows more freedom as providing they remember the letters / numbers they can recreate the sequence in their head, where as digit span relies on a perfect recall of the order of the numbers, meaning it has to be constructed in the correct order first time in the mind or it's gone.

Not sure if that helps.. just my thoughts for now..I have come across it before and it's always a begger to think about. The advanced interpretation book above is useful, think that is where my above thoughts are remembered from but can't be sure as I no longer have a copy!
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Re: Digit span versus letter number sequencing

Post by Borrowed Cone »

In my experience, people have tended to do better on LNS and I have begun to suspect it is not as difficult as is made out. Remember, they must fail 3 trials of the LNS to discontinue compared to just 2 from DS, and whilst this will e reflected to some extent in the conversion to scales scores I do wonder how comparable the two subtests are. Also, many people get freaked out or attention-fatigued by DS. I wonder what order you administered them in, or indeed if they were administered on separate occasions? There certainly seems to be a lager variance in performance on this task than DS in my experience and I personally think DS is a more robust measure of working memory. Just some personal observations.

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Re: Digit span versus letter number sequencing

Post by Lowri »

For what it's worth, I'd echo what Borrowed Cone says: although it looks terrible at first glance, LNS has always struck me as actually more 'straight forward', in that you're given an actual task in which you need to manipulate information - thereby giving you the chance to rehearse and encode it more effectively (remembering my undergrad lectures there...). The alphabetic and counting sequence ordering rules also give a nice 'order' to it all. Furthermore, I've also always found that mere mention of *numbers* can worry people scared off by maths... Just some thoughts...
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Re: Digit span versus letter number sequencing

Post by Gilly »

LNS has a terrible floor affect on it, and you get credit for ordering in whichever order (which always annoyed me) - really dislike it :P
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Re: Digit span versus letter number sequencing

Post by katz »

As has already been mentioned, I often find people panic on DS when numbers are mentioned. sometimes this can impact performance. If this is being done first it is possible that when it comes to sequencing they are less anxious and perform better.

Another thought though. Sometimes I find people who are impulsive perform better on tasks with increased demands/ instructions. When the task seems easy (repeat back to me), people tend to be more impulsive. When they expect the task to me more difficult (i.e. more instructions, sounds more complex), they are primed to consider their answer more carefully/ be less impulsive. This of course may not apply at all but thought it was worth a mention.
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Re: Digit span versus letter number sequencing

Post by miriam »

Lots of interesting thoughts, thanks!
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Re: Digit span versus letter number sequencing

Post by BenJMan »

Gilly wrote:LNS has a terrible floor affect on it, and you get credit for ordering in whichever order (which always annoyed me) - really dislike it :P

Agree !
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Re: Digit span versus letter number sequencing

Post by ell »

Gilly wrote:LNS has a terrible floor affect on it, and you get credit for ordering in whichever order (which always annoyed me) - really dislike it :P
Though a floor effect wouldn't be compatible with people saying the LNS is easier than you think it might be?
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Re: Digit span versus letter number sequencing

Post by BenJMan »

ell wrote:
Gilly wrote:LNS has a terrible floor affect on it, and you get credit for ordering in whichever order (which always annoyed me) - really dislike it :P
Though a floor effect wouldn't be compatible with people saying the LNS is easier than you think it might be?

Whilst anecdotal evidence like that is always interesting, it is the opposite of what I have seen personally (DS has always been easier than LNS) and the normative data for the WISC and WAIS shows than LNS is significantly more difficult for people, to the best of my knowledge anyway.
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Re: Digit span versus letter number sequencing

Post by sally »

Oh how interesting!

Just a reminder - I know that most people contributing here already know this, but as it hasn't been said explicitly:

Both tests are norm-referenced, so it doesn't matter if one is easier than the other (and clearly LNS was designed by the sort of sadistic soul who should rot in hell for eternity) as the assumptions you make about underlying cognitive processes and the numerical values you put to that should mean that everyone finds it equally (and proportionately) more difficult.

Must admit I've come across all sorts of 'spiky profiles in my time and can usually come up with a good explanation as to why that is but I'm a bit stumped on this one - closest I could get is that they have a relatively poor phenomenological loop, but have come up with cognitive strategies to compensate when processing complex information.
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