Questions and Answers about Processing Speed Research
How it impacts learning and why there's nothing you can do about it.
Q: What is processing speed?
A: It’s how fast your brain processes information.
Q: That definition is incredibly unhelpful.
A: I’m sorry, but that’s just how it is! There are certain things your brain does with information, and those things can be done faster or slower.
Q: Well, then how is processing speed measured?
A: By giving people tasks that they can easily do, but measuring how quickly they do them.
Carlozzi, N. E., Tulsky, D. S., Kail, R. V., & Beaumont, J. L. (2013). VI. NIH Toolbox Cognition Battery (CB): measuring processing speed. Monographs of the Society for Research in Child Development, 78(4), 88-102.
The simplest version of this task would include two conditions. In one, participants respond whenever any stimulus appears. In the other, they make one response for certain stimuli (e.g., upper-case letters) but another response for other stimuli (e.g., lower-case letters). […]
Many investigators rely upon psychometric measures of perceptual speed. A typical test of this sort is the Cross Out task from the Woodcock–Johnson Tests of Cognitive Ability. In this test, there are 30 rows with a target geometric figure at the left end of a row and 19 similar figures to the right. … The participant places a line through the five figures of the 19 that are identical to the target figure at the left. The performance measure is the number of rows accurately completed in 3 min.
Q: I’m having trouble imagining those tasks. What do they look like?
A: Below are images of Visual Matching and Cross Out, used to measure processing speed. (Source: YouTube.)
Q: Why does anyone care about processing speed?
A: Because it impacts learning.
Geary, D. C. (2011). Cognitive predictors of achievement growth in mathematics: a 5-year longitudinal study. Developmental psychology, 47(6), 1539.
The domain general abilities that influence learning across many if not all academic areas include general intelligence, working memory, and processing speed (Carroll, 1993; Gottfredson, 1997). Measures of these competences are correlated but each assesses unique abilities.
Fuchs, L. S., Fuchs, D., Compton, D. L., Powell, S. R., Seethaler, P. M., Capizzi, A. M., ... & Fletcher, J. M. (2006). The cognitive correlates of third-grade skill in arithmetic, algorithmic computation, and arithmetic word problems. Journal of Educational Psychology, 98(1), 29.
With respect to the cognitive correlates of arithmetic skill, results revealed its unique and direct relations with attentive behavior, processing speed, and phonological decoding.
Q: How do we know that processing speed impacts learning?
A: Because knowing processing speed allows you to predict how academically successful students will be, even years later.
Geary, D. C. (2011). Cognitive predictors of achievement growth in mathematics: a 5-year longitudinal study. Developmental psychology, 47(6), 1539.
The study's goal was to identify the beginning of first grade quantitative competencies that predict mathematics achievement start point and growth through fifth grade… Multilevel models revealed intelligence, processing speed, and the central executive component of working memory predicted achievement or achievement growth in mathematics and, as a contrast domain, word reading.
Children’s Arithmetical Difficulties: Contributions from Processing Speed, Item Identification, and Short-Term Memory
When reading ability was controlled for, arithmetic ability was best predicted by processing speed, with short-term memory accounting for no further unique variance. It was concluded that children with arithmetic difficulties have problems specifically in automating basic arithmetic facts which may stem from a general speed-of-processing deficit.
Q: Why would processing speed impact learning?
A: This is a sort of subtle point, and wanting to understand it is how I ended up writing this thing.
You can only hold on to information for so long before you lose it—if you process information slowly, that doesn’t make your short-term memory decay slower.
It’s a race against your time-limited mental resources. If you can think faster then you can do more thinking before your time runs out.
Kail, R. (1991). Developmental change in speed of processing during childhood and adolescence. Psychological bulletin, 109(3), 490.
Many cognitive activities require a person's deliberate efforts and people are limited in the amount of effort they can allocate. In the face of limited processing resources, the speed of processing is critical because it determines in part how rapidly limited resources can be reallocated to other cognitive tasks.
Compton, D. L., Fuchs, L. S., Fuchs, D., Lambert, W., & Hamlett, C. (2012). The cognitive and academic profiles of reading and mathematics learning disabilities. Journal of learning disabilities, 45(1), 79-95.
We hypothesized that processing speed may also play a role in the development of more complex academic skills because it may affect how quickly lower level skills, which have already been acquired with relative accuracy, can be executed. Slow processing speed creates the possibility that decay in the completion of lower level skills (e.g., connecting sounds and letters in multisyllabic decoding, connecting problems stems with answers in arithmetic) sets in before the more complex skill, which incorporates these tasks, is completed.
Here’s another way of thinking about this dynamic. Imagine a college lecture where the professor simply speaks for an hour. There are no learning activities. There is no pause for questions. It’s just talk, talk, talk. You and I know that this isn’t great teaching. But people can learn from it anyway, as long as they can think about the lecture fast enough. If you process information more quickly, it’s probably easier to learn from ineffective teaching.
(This point wasn’t obvious to me. Like, couldn’t it have been possibl that processing speed was just a total brain multiplier, and items held in working memory decayed faster also? But I guess that’s just not how it works? What do I know.)
Q: Does processing speed impact your reasoning ability?
A: Yes, for the above reasons, and also one more: it might impact your motivation.
In other words, it may simply be demotivating to take longer to perform a task. Our sense of progress can be impacted by the progress that those around us are making in a social context, like a classroom. But it also can be loopier. My sense of how long something is supposed to take may be socially internalized. Then, I take that with me wherever I go.
Q: Does a person’s processing speed change during their life?
A: Yes, definitely.
Q: How?
A: Babies process information relatively slowly. We get faster as we grow up, peak as young adults, and then spend the rest of our lives getting slower. Both the increase with age and (especially) the decrease in youth follow an exponential curve.
Kail, R., & Salthouse, T. A. (1994). Processing speed as a mental capacity. Acta psychologica, 86(2-3), 199-225.
The speed of many types of processing follows a regular trajectory over the course of the lifespan. Speed increases throughout childhood and adolescence, reaches a peak in young adulthood, and declines slowly thereafter (Salthouse and Kail, 1983).
Q: What drives changes in reaction time?
A: It doesn’t seem like a settled question. Some people think it’s the key to decline in cognitive abilities as we age.
Geary, D. C. (2011). Consequences, characteristics, and causes of mathematical learning disabilities and persistent low achievement in mathematics. Journal of Developmental & Behavioral Pediatrics, 32(3), 250-263.
The mechanisms underlying this pattern are not fully understood but may include substantial improvements in the attentional focus component of the central executive and rapid increases in neuronal white matter (which speeds neural transmission) during this age range.
Salthouse, T. A. (1996). The processing-speed theory of adult age differences in cognition. Psychological review, 103(3), 403.
A theory is proposed to account for some of the age-related differences reported in measures of Type A or fluid cognition. The central hypothesis in the theory is that increased age in adulthood is associated with a decrease in the speed with which many processing operations can be executed and that this reduction in speed leads to impairments in cognitive functioning because of what are termed the limited time mechanism and the simultaneity mechanism. That is, cognitive performance is degraded when processing is slow because relevant operations cannot be successfully executed (limited time) and because the products of early processing may no longer be available when later processing is complete (simultaneity).
Q: If a student processes information slowly, what can you do to help them?
A: Nothing that you wouldn’t already be doing to help any struggling student, I don’t think. Not that there isn’t any way to help—it’s just that it’s not a limited, specific thing. Instead it’s the big thing, which is how do you teach kids so that more of them learn the stuff? There’s no simple fix for processing speed, in other words.
Q: This is all fairly interesting, but does any of this matter for a teacher?
A: So, on the one hand: no, it does not. Processing speed is a fairly global property of a person. It supposedly impacts all their processes. There doesn’t seem to be any reliable way to improve it. So, it just is what it is, but it’s something fairly objective that you can measure about a child. That makes it valuable for evaluation.
But, on the other hand, don’t we want to know how learning and reasoning works? It all helps us flesh out an accurate model of classroom learning. And, to get specific, it helps us understand the ways in which speedy or slow thinking can help or hinder a student. So I think, yes, it does matter, because when it comes to understanding how learning works, it all matters.