מפל התפתחותי: השפעת מהירות העיבוד וזיכרון העבודה על היכולת הפלואידית

 

 ארבעה מפלים של טילים מאיראן על הישוב שלי הבוקר, ואני יושבת בממ"ד וכותבת פוסט על מפל של יכולות קוגניטיביות - סוג של אסקפיזם.

מהירות העיבוד נחשבת לעתים ליכולת פשוטה, טכנית, שאינה קשורה לחשיבה גבוהה, ושתרומתה לרמת המשכל הכללית היא נמוכה.

אולם מסתבר שמהירות העיבוד משחקת תפקיד חשוב בהתפתחות היכולת לחשיבה מופשטת. בסדרה של מחקרים שמופיעים בטבלה למטה נמצאה תופעה של מפל התפתחותי: עליה עם הגיל במהירות העיבוד מובילה לעליה בקיבולת זיכרון העבודה שמובילה לעליה ביכולת הפלואידית. מכיוון שתופעה זו חוזרת ומופיעה במחקרים רבים, היא ככל הנראה חזקה ביותר.

מה ההסבר לתופעת המפל? היכולת לחשוב ולפתור בעיות דורשת ביצוע מניפולציה במידע שמוחזק בזיכרון העבודה. כמות הפריטים שאנחנו יכולים להחזיק בזיכרון העבודה היא מוגבלת, ופריטים אלה דועכים אם לא משננים אותם "בלב", או אובדים בשל הפרעות. החוקר Salthouse (1996)  טוען שעיבוד מהיר יותר משפר את זיכרון העבודה בכך שהוא מאפשר לאדם להשלים את תהליך החשיבה לפני שהמידע בזיכרון העבודה דועך. מהירות העיבוד עוזרת להשלים את תהליך החשיבה גם כאשר תנאי הסביבה מגבילים את הזמן בו המידע זמין, למשל כאשר מעבדים שפה דבורה.

בגלל שכמות המידע שניתן להחזיק בזיכרון העבודה מגבילה את יכולת החשיבה, קיבולת גבוהה יותר של זיכרון עבודה קשורה לחשיבה טובה יותר, כלומר ליכולת פלואידית גבוהה יותר.

מודל המפל מדגיש שהיכולות הקוגניטיביות משפיעות זו על זו ולא עובדות כל אחת בנפרד. לכן, כשיש לילד כמה יכולות נמוכות, ההשפעה של כל ההנמכות ביחד גבוהה יותר מההשפעה של כל הנמכה בנפרד. כל אחת מהיכולות הנמוכות "מושכת" את היכולות הנמוכות האחרות עוד יותר למטה.

כאשר יש לילד מספר יכולות נמוכות, כדאי לחשוב מהו מוקד הקושי, מה מבין היכולות הנמוכות היא היכולת העיקרית שפוגעת בתפקוד של הילד (בקריאה, כתיבה, חשבון ו/או בתפקוד החברתי והרגשי), וכיצד יכולת זו משפיעה לרעה על היכולות האחרות.

כאשר היכולות הנמוכות הן מהירות עיבוד, זיכרון עבודה ויכולת פלואידית, מודל המפל מצביע על מהירות העיבוד כמוקד קושי ראשוני שגורר אחריו הנמכה בזיכרון עבודה וביכולת הפלואידית. כך, הנמכה במהירות עיבוד עלולה להגביל את ההתפתחות של היכולת הפלואידית.

טבלה מס.1: מחקרים שבדקו את מודל המפל

מחקר	מה עשו	מה מצאו
Fry and Hale, 1996	ילדים בני 7-19 עברו מבחנים שבדקו מהירות עיבוד, זיכרון עבודה ויכולת פלואידית (מטריצות רייבן)	עליה עם הגיל במהירות העיבוד הובילה לעליה בקיבולת זיכרון העבודה שהובילה לעליה ביכולת הפלואידית.
Kail, 2007	ילדים בני 8-13 עברו מבחנים שבדקו מהירות עיבוד (התאמה חזותית ואיתור ציורים מהיר מהוודקוק), זיכרון עבודה ויכולת פלואידית (מטריצות רייבן). הילדים נבחנו שוב שנה לאחר המבחן הראשון.	עליה עם הגיל במהירות העיבוד הובילה לעליה בקיבולת זיכרון העבודה שהובילה לעליה ביכולת הפלואידית. זה התקבל הן בקבוצות הגיל השונות והן בין המדידה הראשונה לשניה.
Nettelbeck and Burns, 2010	ילדים בני 8-14 עברו מבחנים שבדקו מהירות עיבוד, זיכרון עבודה ויכולת פלואידית.	עליה עם הגיל במהירות העיבוד הובילה לעליה בקיבולת זיכרון העבודה שהובילה לעליה ביכולת הפלואידית.
De Alwis et al., 2014	ילדים בני 6-12 עברו מבחנים של מהירות עיבוד, זיכרון עבודה, יעילות למידה (דומים ל- REY AVLT - ריי שמיעתי) ויכולת פלואידית (מטריצות ממבחן WISC4 ומהרייבן).	עליה עם הגיל במהירות העיבוד הובילה לקיבולת גדולה יותר של זיכרון עבודה שהובילה ליכולת פלואידית גבוהה יותר. יעילות למידה לא הסבירה שונות ייחודית ביכולת הפלואידית מעבר לשונות שהוסברה על ידי זיכרון העבודה.
Kail et al., 2016	ילדים בני 6-13 עברו שישה מועדי בחינה (לאורך שנתיים וחצי) בהם נבדקו מהירות עיבוד (התאמה חזותית ואיתור ציורים מהיר מהוודקוק), זיכרון עבודה ויכולת פלואידית (מטריצות רייבן). השוו בין הביצועים של הילדים בשלוש נקודות זמן.	מהירות עיבוד הובילה ישירות לשיפור ביכולת הפלואידית. התקבלה עדות חלשה יותר להשפעה של מהירות עיבוד על היכולת הפלואידית באמצעות זיכרון העבודה. זיכרון עבודה במועד הראשון ניבא יכולת פלואידית במועד השני.
Tourva and Spanoudis, 2020	נבדקים בני 7-18 עברו מבחנים שבדקו מהירות עיבוד (זמן תגובה לגירויים פשוטים, למשל להחליט כמה שיותר מהר אם חץ פונה ימינה או שמאלה, אינהיביציה, זיכרון עבודה, יכולת פלואידית (סידור קוביות ומטריצות) וידע מגובש (אוצר מילים וצד שווה).	עליה עם הגיל במהירות העיבוד שהובילה לשיפור באינהיביציה ולשיפור בזיכרון העבודה. שיפור בזיכרון העבודה הוביל לעליה ביכולת הפלואידית ובידע המגובש.

 

האם טיפול במהירות העיבוד יכול להשפיע לטובה על זיכרון עבודה ועל היכולת הפלואידית? החוקרת אליסון מאקי (Mackey et al., 2011) אימנה ילדים בני 7-9 בשני סוגים של אימון אינטנסיבי. קבוצה אחת אימנה את היכולת הפלואידית באמצעות משחקים שהיה בהם דגש על תכנון ואינטגרציה. קבוצה שניה אימנה את מהירות העיבוד באמצעות משחקים שהדגישו עיבוד מהיר ותגובה מוטורית מהירה. שתי הקבוצות עברו מבחנים שבדקו את היכולת הפלואידית (מבחן מטריצות) ואת מהירות העיבוד (מבחן קידוד מהוכסלר ומבחן איתור ציורים מהיר מהוודקוק) לפני ואחרי האימון.

הילדים בקבוצת האימון הפלואידי שיפרו מאד את הביצוע שלהם במבחן המטריצות לאחר האימון, אך לא שיפרו את הביצוע במבחני מהירות העיבוד. הילדים בקבוצה שאימנה את מהירות העיבוד שיפרה מאד את הביצוע במבחני מהירות העיבוד, אך לא שיפרה את הביצוע במבחן המטריצות. כלומר, אימון מהירות העיבוד לא השפיע לטובה על היכולת הפלואידית. מאכזב!

מצד שני, המחקר הזה מראה שאימון מהירות העיבוד מצליח לשפר את מהירות העיבוד, ושאימון של היכולת הפלואידית מצליח לשפר אותה. יתרה מזו: נבדקים שקיבלו ציונים נמוכים במבחן המטריצות לפני האימון השתפרו יותר במבחן זה בעקבות אימון היכולת הפלואידית מנבדקים שקיבלו ציונים גבוהים במבחן המטריצות לפני האימון! ממצאים אלה מדגישים בפנינו שהביצוע של ילדים במבחנים שבודקים יכולת פלואידית מושפע מחשיפה ומהתנסות במטלות דומות או בדרכי חשיבה דומות, התנסות שילדים מרקע פחות מטפח פחות חשופים לה. חשוב לקחת זאת בחשבון כאשר מעריכים את היכולת הפלואידית אצל ילדים מרקע פחות מטפח. כאשר ילדים כאלה מקבלים הזדמנות, יש להם סיכוי רב לשפר את היכולת הפלואידית.

 

 

De Alwis D, Hale S, Myerson J. Extended cascade models of age and individual differences in children’s fluid intelligence. Intelligence. 2014; 46:84–93. doi: 10.1016/j.intell.2014.05.008

Fry, A. F., & Hale, S. (1996). Processing speed, working memory, and fluid intelligence: Evidence for a developmental cascade. Psychological Science, 7,237–241.

Fry, A. F., & Hale, S. (2000). Relationships among processing speed, working memory and fluid intelligence in children. Biological Psychology, 54, 1–34.

Kail, R. V. (2007). Longitudinal evidence that increases in processing speed and working memory enhance children's reasoning. Psychological Science, 18(4), 312–313. https://doi.org/10.1111/j.1467-9280.2007.01895.x

Kail, R. V., Lervåg, A., & Hulme, C. (2016). Longitudinal evidence linking processing speed to the development of reasoning. Developmental science, 19(6), 1067-1074.

Mackey AP, Hill SS, Stone SI, Bunge SA. Differential effects of reasoning and speed training in children. Developmental Science. 2011; 14:582–590. doi: 10.1111/j.1467-7687.2010.01005.x. [PubMed: 21477196]

Nettelbeck, T., & Burns, N. R. (2010). Processing speed, working memory and reasoning ability from childhood to old age. Personality and Individual Differences, 48(4), 379-384.

Salthouse, T. A. (1996). The processing-speed theory of adult age differences in cognition. Psychological Review, 103, 403–428.

Tourva, A., & Spanoudis, G. (2020). Speed of processing, control of processing, working memory and crystallized and fluid intelligence: Evidence for a developmental cascade. Intelligence, 83, 101503.

 

 

What cognitive abilities are involved in trail-making performance?

Salthouse, T. A. (2011). What cognitive abilities are involved in trail-making performance?  Intelligence, 39(4), 222-232.‏

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3141679/

In this paper, the renowned scholar Salthouse attempted to find out what cognitive abilities are involved in the TMT test.  The research was done with adults.  Will children's results be the same?  That's an interesting question.

Salthouse is a professor of psychology in Virginia University, where he studies the process of cognitive aging.  He published 10 books and over 250 chapters and papers.

 

 

Salthouse used a slightly different version of the TMT test than the version most of us are familiar with.  This version, the Connections test, has 49 circles containing numbers or letters in each stage of the task.  Like in the TMT test, one has to connect numbers only, numbers alternating with letters (1-A-2-B-3-C etc.) and letters only (A-B-C…this part does not exist in all familiar versions).  One of the differences between the Connections test and the TMT test is that in the Connections test the influences of visual search and hand movements have been minimized since the "targets" (the circles one has to reach in the sequence performed) are close together and not widely scattered on the page.  Another difference is that one gets 20 seconds to work on each page, instead of measuring the time needed to complete the page.  Research has shown that the Connections test is loaded with the same factors as the TMT test.  This means that the tests are highly equivalent. 

Despite their simplicity, researchers think that TMT tests reflect a wide variety of cognitive processes including attention, visual search and scanning, sequencing and shifting, psychomotor speed, abstraction, flexibility, the ability to perform and to alter a plan for action, and an ability to keep two lines of thought in mind simultaneously.

Some scholars argue that performance in the TMT reflects executive functions.  Salthouse writes that since there is a very close connection between fluid ability and executive functions, it can be predicted that fluid ability will affect performance on the TMT.  Other scholars argue that working memory affects performance in the TMT because of the need to keep track of the number and letter sequences.  Since there is a very strong empirical relation between fluid ability and working memory, Salthouse asked himself if working memory has a unique contribution to performance in the TMT, beyond the presumed contributions of processing speed and fluid ability. 

The study was done with a large sample of adults aged 18 to 98 (I admire 98 year olds who are willing to participate in such studies!).  The participants performed the Connections test and tests measuring fluid ability, long term memory, processing speed and vocabulary.

  Like other studies, this study reveals unpleasant facts about the influence of aging on cognitive abilities, and one ray of hope.  As we can see in the attached figure, fluid ability, long term memory and processing speed deteriorate from the age of 20 (participants in this study were recruited through advertisement.  In each age group – in each decade, there were between 220 and 830 subjects.  Generally, the participants in this study performed better on the tests than normative samples).  Vocabulary is the ray of hope.  Vocabulary keeps rising between ages 20 to 65, and then it deteriorates slightly, but remains in the average level.

The difference in processing speed between part A and part B of the Connections test was smaller at the older ages (performance speed in part A deteriorated faster than performance speed in part B, and thus the two parts came closer together).

In part A, processing speed affected performance more than fluid ability, which also affected performance significantly.  In part B, the results were reversed:  fluid ability affected performance more than processing speed, which also affected performance significantly.  The difference in performance speed between part A and part B was affected only by processing speed.  People with a high processing speed had a larger difference between speed of performance in part A and part B than people with low processing speed. 

Here we can see something odd – inferences about relations of cognitive abilities on Connections performance  vary depending on the particular measure of performance examined. Performance on the Connections test was affected in a moderate to a large degree by processing speed in parts A and B.  Processing speed probably affects performance because of the need for fast response on both parts.  Performance in the Connections test was affected in a moderate to a large degree by fluid ability, both in part A and in part B.  Fluid ability probably affects performance because of the need to keep one's place in the current sequence while one looks for the next element in the sequence.  This is required on both parts of the test.  There was a special relation between fluid ability and performance in part B.  This means that fluid ability affects the ability to switch between sequences.  There was no relation of fluid ability with the difference score (B–A) measure. The difference score reflected mainly processing speed.

There was no significant relation between working memory and performance on the Connections test.  I think that working memory was assessed here with very complex tasks, resembling fluid tasks.  This may be the reason for the lack of influence of working memory on the performance on the TMT beyond the influence of fluid ability.

Other studies, like this of Hoelzle, also found that the TMT test measures processing speed (and not working memory)

 

Hoelzle, J. B. (2008). Neuropsychological assessment and the Cattell-Horn-Carroll (CHC) cognitive abilities model. ProQuest.‏    PAGE 114   http://utdr.utoledo.edu/cgi/viewcontent.cgi?article=2213&context=theses-dissertations

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.

It's time for debate in the assessment of intelligence! A processing speed example

In the psychotherapy field there are different theoretical approaches (for instance, different dynamic theories, CBT theories, family theories).  Each of these approaches leads to a different view of the client and his difficulties, a view that leads to a different line of intervention.  These approaches are both at an external debate with each other and at an internal dispute (in each of these fields there are subtheories that are arguing with each other).   This debate enriches the development of each of these approaches, since it forces them to clarify their positions. 

What about the diagnostic field?

Where are the different approaches, the different views of the child? The debates?

In the field of learning disabilities there certainly is a debate, as I've written about extensively here.

In the broad field of assessment, and especially in the intelligence field, there are different schools as well.  It's important that we know them because they enrich our view of the child and open new and diverse ways for intervention.  Of the several existing approaches I will mention three:  The psychometric approach (CHC is one of the psychometric theories), the cognitive approach (PASS theory, that is the basis for the KABC test is one of the cognitive theories) and the social-cultural (my term) approach (the Triarchic theory by Sternberg and the Dual theory by Kaufman (here) are representative of this approach).

Here is an example, with processing speed, of the advantage that we gain by having two different theoretical viewpoints.   

Processing speed as defined in CHC theory is the speed and fluency with which a person can perform a task in which the rate of performance is under his control, and that requires attentional resources.  The word "automatic" is the key word for processing speed, because processing speed enables us to reach an automatic and fluent performance of newly learned tasks.  When we learn to play a new musical piece, for example, our performance in the first attempts will be slow and laborious, but with practice performance will become more and more fluent and automatic.  Then we will have free attentional resources to devote to musical expression.  But if we are unlucky to have a slow processing speed, we may need much more practice to reach fluency and automaticity, or we may never reach them, and never have enough free attentional resources to express the musicality of the piece.

Processing speed affects reading and writing in the same way.  A child whose processing speed is slow will find it difficult if not impossible to read fluently and automatically, and will have few free attentional resources for reading comprehension.  A child whose processing speed is slow will find it  difficult  if not impossible to write fluently and automatically, and will have few free attentional resources for expressing his ideas in writing the way he wants them expressed.  Processing speed may affect social functioning as well:  a child whose processing speed is slow will have difficulty playing games that require fluent performance, like jumping rope or handclapping games.  A child whose processing speed is slow may have difficulty participating in conversation, because while he processes what has been said and prepares his contribution, the conversation flows on…

Research on the relation between processing speed and attention tells us that the inattention component affects processing sped.  Thus when we assess a child whose processing speed is slow, it will be a good idea to see if he has attention problems.  Such a child will need to practice new tasks more for them to become automatic.  If the child has difficulties in reading fluency that are caused by processing speed, we may recommend re-reading the same text over and over, each time faster, in order to improve automaticity.

All this is from a CHC point of view.

But we can also look at low processing speed from the point of view of Woodcock's cognitive model (a bit more about this model here).

(Click on the figure to enlarge).

The model consists of a few interacting systems that are used for information processing and the performance of different cognitive tasks.  A quick glance at the figure above reveals us that processing speed belongs, along with short term memory, to the cognitive efficiency system.  This system forms a "bottleneck" for information processing.  We see that it is positioned between input and output ("cognitive academic performance") and we can't do without it.  This model offers us another way to deal with slow processing speed:  strengthening short term memory.

The best analogy I can think of in this context is…the Iranian nuclear program.  Suppose we need 3 centrifuges that spin at a certain speed to make an atom bomb. What can we do if we are unlucky to have especially slow centrifuges, that are spinning at half the speed of average centrifuges?  We can add  three more centrifuges!  If the number of centrifuges represents working memory capacity, we can overcome low processing speed by strengthening short term memory.  There is research that claims this can be done.  The n – back task (of which I've written here) is one such means.

I'm not sure that this analogy is right concerning centrifuges…but for our business it works.

So, looking at low processing speed from the point of view of cognitive theory opened intervention opportunities that were not available to us when we looked at processing speed from the psychometric point of view.  This exemplifies the advantage of being familiar with different theoretical approaches in the assessment field at large and in the intelligence field in particular.

Intelligence and cognitive abilities part 5: General cognitive speed - processing speed, reaction and decision speed

Intelligence and cognitive abilities part 5:

General cognitive speed:  processing speed, reaction and decision speed

(part 4 is not published yet as I'm still writing it)