1/2/2024 0 Comments Backward digit span test raceThis is clearer in the second table, which shows the gaps as Cohen’s d The chart shows the increase in digit span with increasing age, and the nature of the gap between digits forwards and backwards in the different groups. Gradually we are getting to understand the transmission of intelligence through the generations. Incidentally, this is a great follow-up survey: “My Mummy did your tests before I was born”. Over at Human Varieties, Dalliard has tried to replicate those results using data from CNLSY (these are the children of the female participants in NLSY79). 405, referring to work he did in 1975 with Figueroa, ref on p 614). Hence the great interest in the most recent scores, to see if they conform to the usual pattern described by Jensen in the G factor (p. The higher the g loading the more they should differ from brighter groups. If any group defined in genetic or cultural terms has a particular difficulty with digits backwards this is a strong indicator that they have difficulty with tasks as they get more intellectually demanding. (What name would one give to a culture in which number use is discouraged?) Could there really be a culture in which there are numbers but no reversible operations? Even if there were a culture or putative sub-culture in which using numbers was discouraged, it should affect all digit tasks, not just digits backwards. How does this finding relate to the vexed question of group differences? Well, it is hard to give a plausible cultural explanation for the effect, unless you stretch the concept of culture to absurd lengths. Digits forwards are related to g, but digits backwards are even more loaded on g. (At age 11 for white kids the reduction is 23% and for black kids 30%, as shown below). If someone can remember 7 digits forward (the average adult score) but only 6 backwards (the average adult core), that is a 14% reduction in memory capacity. Digit backwards spans are usually at least a digit shorter than digits forwards. That simple little task of remembering the forward sequence, and then keeping it in mind while reading off the sequence in reverse order taxes the mind. Most of the intellectual demand comes from digits backwards. How does digit backwards have this profound effect? Short term memory is just an auditory store. Of course, Wechsler being Wechsler, they have also included some new tasks in Digit Span, in which digits are read to the examinee and have to be remembered back in order of magnitude, but we can leave that out for the time being, since it does not affect the central comparison between digits forwards and backwards. Once extra trials are provided, Digit Span becomes a good measure of general intelligence, correlating with g at 0.71. Arthur Jensen pointed out that this was simply because not enough trials were used. Initially, test constructors regarded the test as an optional extra, because test-retest reliabilities were low. I assume that forwards and backwards are concepts understood by all cultures worthy of the name. Once you have learnt digit names you are ready to do the test. The test is not only bereft of intellectual content, but is also low on cultural content. In particular, if you can do digits forwards you reveal you know your digits and have some memory, and if you can do a short string backwards you reveal that you have some memory and you understand the idea of repeating digits backwards. All you need is: to know the names of single digits, and to understand the simple instructions and examples given so that you repeat the digits forwards, and in the later version of the test, backwards. I hope you will agree that this is a simple test, easy to understand, and largely bereft of any intellectual content. This continues until the examinee fails two trials at a particular length which determines the number of digits backwards. For example, 3 – 7 is to be said back to the examiner as 7 –3. Then the examiner explains that he will say a string of digits and the examinee has to repeat them backwards, that is, in reverse order. ![]() That determines the number of digits forwards. The examiner then tries a string which is one digit longer, and continues in this fashion with longer and longer strings of digits until the examinee fails both trials at that particular length. The examiner says a short string of digits at the rate of one digit a second in a monotone voice, and then the examinee repeats them. Digit Span must be one of the simplest tests ever devised.
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