An auditory processing speed test?

Cameron, S., Glyde, H., Dillon, H., & Whitfield, J. (2014).Development and Preliminary Evaluation of a Processing Speed Test for School-Aged Children Utilizing Auditory Stimuli. International Journal of School and Cognitive Psychology, 2014.‏  http://www.omicsonline.com/open-access/development-and-preliminary-evaluation-of-a-processing-speed-test-for-school-aged-children-utilizing-auditory-stimuli-1234-3425.1000116.pdf

We are used to assessing processing speed via visual – motor tasks.  But processing speed exists in all modalities (auditory, tactile and probably also olfactory and taste…).  Assessing processing speed in more than one modality will possibly give us a more reliable picture of the child's functioning in this ability.  Cameron and his colleagues devised a test to assess auditory processing speed. Despite its shortcomings, I think this test is an interesting and important endeavor.

Processing speed is the rate at which a person performs simple perceptual or cognitive tasks with reasonable accuracy.  Processing speed affects the rate at which a person can think, process sensory information or perform other cognitive processes like remembering or understanding language.  Processing speed measures include a variety of tasks, including associating numbers with symbols, searching for and responding to specific targets, and rapid naming of visual stimuli (in CHC terms, rapid automatic naming, especially in tests where the child rapidly names many different stimuli, is a measure of retrieval fluency, which is a narrow ability within Long Term Storage and Retrieval, but it also has a significant element of processing speed). 

 Individual differences in processing speed have been shown to influence academic performance in the classroom.  Processing speed underlies many cognitive skills including reading word recognition, reading comprehension, verbal ability, and verbal reasoning (in order to understand texts, we have to be able to encode the words and link them to their semantic meanings fluently and automatically, and to process the ideas in the text at the reading speed.  In order to understand the teacher and participate in class discussions we have to process the ideas we hear at a pace that matches the teacher's speaking rate or the conversation rate, and to plan the verbal message we want to convey at a rate that matches the conversation rate).

In a study of 214 children aged 7 to 19, it was found that individual differences in processing speed directly affect working memory capacity, which in turn cause interpersonal differences in fluid ability.  I think that there is an interaction between processing speed and working memory capacity ("capacity" is the number of items that can be "held" in working memory).  When processing speed is fast, one can process more with the same working memory capacity.  When processing speed is slow, a larger working memory capacity can make up for it, because the larger capacity allows one to hold more pieces of information before they decay, so that one is able to process them even when information flows slowly.

Twenty school-aged children with specific language impairment (SLI) took part in a study which investigated reduced speech input rate could enhance language processing. A word recognition reaction time task was used whereby participants monitored simple sentences for a target word and made a timed response immediately upon recognizing the target. Sentences were presented at normal speaking rate, a slow rate (time expanded by 25 per cent) and a fast rate (time compressed by 25 per cent). Results were compared to 20 age matched typically developing (TD) children. The SLI group had significantly slower reactions times than the controls for the normal and fast-rate sentences, but faster reaction times for slow-rate sentences.   Children with SLI produced the fastest reaction times for slow-rate sentences and the slowest reaction times for fast-rate sentences. In comparison, the controls showed the fastest reaction times for fast-rate sentences and the slowest reaction times for slow-rate sentences.   Interestingly, even the oldest children with SLI still demonstrated significantly slower reaction times than the youngest TD children on the normal and fast-rate sentences. The author concluded that the language processing of children with SLI can be enhanced by presenting material at a slower rate, as the rate of processing allows such children time to allocate their attentional resources more effectively to the various processing operations supporting comprehension.

Apparently, it's possible to assess the auditory processing speed of babies!  Researchers compared two groups of six month old babies:  one that had a family history of SLI, and another without such history.  The babies listened to a specific repetitive sound pattern, and were trained to turn their heads when they heard a different sound pattern.  Then, whenever the baby succeeded, the inter-sound interval in each pattern was shortened (the pattern was played faster).  Whenever the baby failed, the inter-sound interval in each pattern was lengthened (the pattern was played slower).  Thus, the researchers adjusted the pattern's pace to the baby, until the baby's auditory processing speed was determined (it was the fastest  rate at which the baby was still able to perform the task).  A significant difference was found between the auditory processing speed of the babies in the two groups (the direction of the difference is not written, so I assume that babies with a family history of SLI had slower auditory processing speed).  Auditory processing speed was also the single best predictor of language outcomes at two years of age based on a large battery of sensory, perceptual and cognitive measures. By three years of age, two variables — auditory processing speed obtained at 6 months and male gender — together predicted 39–41% of the variance in language outcome.

Cameron and his colleagues developed a computerized test to assess auditory processing speed in children, and tested it with children in first to sixth grades.  The 174 children tested did not have attention or hearing problems.  The test took 15 minutes (a bit too lengthy…).  During the test the child heard, in random order, nouns (common objects, animals and body parts) and number words (five possible words: "one", "two", "three", "four", "five").  The child's task was to respond by pressing the mouse whenever he hears a number word.  Up to this point the test sounds like an attention test.  This is sensible, since we know that inattention has a detrimental effect on processing speed.  Processing speed is the rate and the fluency with which a person can perform a task that demands attentional resources. 

Processing speed was assessed in Cameron and his colleagues' test in a similar manner to the way it was assessed in the babies' test:  when the child correctly identified two number words, the word stream was played faster.  When the child did not identify a number word or pressed the mouse when a noun was sounded, the word stream was played slower.  Thus the rate of presentation of the word stream was adjusted until the child's auditory processing speed was determined (the fastest rate at which the child could perform the task).  The child's auditory processing speed was computed in terms of words per minute (the number of words the child could process in a minute).

The children's scores on this test were normally distributed.  The average auditory processing speed of first grade children was 39 words per minute and of sixth grade children – 59 words per minute.  Older children's processing speed was significantly faster than younger children's processing speed.  Every year auditory processing speed increased in four words per minute. 

A serious problem in the test was a positive correlation that was found between impulsivity and processing  speed.  Each one standard deviation rise in impulsivity was correlated with half a standard deviation rise in processing speed.  This finding indicates an error in the test, since an impulsive child should not be "rewarded" with a faster processing speed.

Beyond that, Schneider  and McGrew define processing speed this way:

the speed and fluency with which a person can perform a self paced, attention demanding task.  In processing speed tasks, the stimuli are all presented together (for example, the child is handed a piece of paper with visual stimuli), and the child controls his working speed.  In Cameron's test each stimulus was presented separately (by the nature of auditory presentation), and the child did not control his working pace (although the pace was adjusted to him).  Is Schneider and McGrew's  definition is too restrictive?  In daily tasks that require processing speed, the rate of stimuli presentation is not always in our control.  When we read a book, our reading rate and processing speed is indeed in our control.  But when we listen to a teacher talking in class, her speaking rate is not in our control.