Try out PMC Labs and tell us what you think. Learn More. On one hand, intelligence testing is one of the great successes of psychology Hunt, Intelligence test scores predict many real world phenomena and have many well-validated practical uses Gottfredson, ; Deary et al.
Intelligence test scores also correlate to structural and functional brain parameters assessed with neuroimaging Haier et al.
On the other hand, intelligence test scores are often misunderstood and can be misused. This paper focuses on a basic misunderstanding that permeates many of the recent reports of increased intelligence following short-term cognitive training.
Several of these reports have been published in prominent journals and received wide public attention Jaeggi et al. The basic misunderstanding is assuming that intelligence test scores are units of measurement like inches or liters or grams. They are not. Inches, liters and grams are ratio scales where zero means zero and units are twice 50 units.
Intelligence test scores estimate a construct using interval scales and have meaning only relative to other people of the same age and sex. A change from an IQ score from to is not the same as a change from to This makes simple interpretation of intelligence test score changes impossible. Most recent studies that have claimed increases in intelligence after a cognitive training intervention rely on comparing an intelligence test score before the intervention to a second score after the intervention.
If there is an average change score increase for the training group that is statistically significant using a dependent t-test or similar statistical test , this is treated as evidence that intelligence has increased.
This reasoning is correct if one is measuring ratio scales like inches, liters or grams before and after some intervention assuming suitable and reliable instruments like rulers to avoid erroneous Cold Fusion-like conclusions that apparently were based on faulty heat measurement ; it is not correct for intelligence test scores on interval scales that only estimate a relative rank order rather than measure the construct of intelligence.
Even though the estimate has considerable predictive value and correlates to brain and genetic measures, it is not a measurement in the same way we measure distance, liquid, or weight even if individual change scores are used in a pre-post design. SAT scores, for example, are highly correlated to intelligence test scores Frey and Detterman, Imagine a student takes the SATs when quite ill.
The scores likely are a bad estimate of the student's ability. If the student retakes the test sometime later when well, does an increase in score mean the student's intelligence has increased, or that the newer score is now just a better estimate? The same is true for score changes following SAT preparatory courses. Many colleges and universities allow applicants to submit multiple SAT scores and the highest score typically carries the most weight; there are many spurious reasons for low scores but far fewer for high scores.
Change scores from lowest to highest carry little if any weight. By contrast, change in a person's weight after some intervention is unambiguous. In studies of the effect of cognitive training on intelligence, it is also important to understand that all intelligence test scores include a certain amount of imprecision or error.
The standard error of measuring inches or liters is usually zero assuming you have perfectly reliable, standard measurement devices.
Intelligence tests generally show high test-retest reliability but they also have a standard error, and the standard error is often larger for higher scores than for lower scores. Any intelligence test score change after an intervention needs to be considered relative to the standard error of the test.
Studies that use a single test to estimate intelligence before and after an intervention are using less reliable and more variable scores bigger standard errors than studies that combine scores from a battery of tests. Change scores are never easy to interpret and require sophisticated statistical methods and research designs with appropriate control groups. If you try a training intervention in individuals all of whom have pre-intervention scores below the population mean, for example, re-testing with or without any intervention, may result in higher scores due to the statistical phenomenon of regression to the mean, or due to simple test practice, especially if equivalent alternative forms of the test are not used.
Quasi-experimental designs like post-test only with large samples and random assignment do not have all the same interpretation difficulties as pre-post designs. They have promise but most reviewers are more inclined to value pre-post changes.
Latent variable techniques also avoid many of the difficulties of pre-post interval scale changes and they have promise in large samples Ferrer and McArdle, When change scores are used, it is important to identify individual differences even within a group where the average change score statistically increases after an intervention. Imagine a group of students received cognitive training and others received some control intervention.
The mean change score in the training group may statistically show a greater increase than the controls. How many of the individuals who received the training actually show an increase? Do they differ in any way from the individuals in the same group who do not show an increase? Does item analysis show whether increased scores are due more to easy test items or hard ones? What about any individuals in the control group that show change score increases as large as shown in the training group?
If all participants ultimately get the same training, will the rank order of individuals based on the post-training score be any different than the rank order based on the pre-training scores?
If not, what has been accomplished? Where and why g matters: Not a mystery. Human Performance, doi Intelligence and socioeconomic success: A meta-analytic review of longitudinal research. In addition, this recognition may be further extended to countries, as well. For instance, the project entitled, Foresight Project on Mental Capital and Wellbeing, which involved experts from 16 countries, it is emphasized that countries must be concerned with: a how to capitalize on their citizens's cognitive resources, b promoting early interventions, and c empowering people to develop and maintain their mental capital and wellbeing Beddington et al.
Thomas, S. The mental wealth of nations. Nature, Thus, there is a renewed interest in the scientific literature regarding these interventions, whether at the individual or the national level, to increase the intelligence or cognitive abilities of people Nisbett, Nisbett, R.
Intelligence and how to get it: Why schools and cultures count. New York: W. Intelligence: New findings and theoretical developments. American Psychologist, doi Among these interventions are those related to working memory WM , understood as a cognitive system that stores and manipulates a limited amount of information for a short period of time Baddeley, Baddeley, A. Working memory: Looking back and looking forward. Nature Reviews: Neuroscience, 4: doi Dificultades en el rendimiento escolar y la memoria de trabajo.
Pro-ceedings of the National Academy of Sciences, doi Improving fluid intelligence with training on working memory. Proceedings of the National Academy of Sciences, doi Does working memory training generalize?
Psychologica Belgica, doi Several recent studies have indicated that adequate training can lead to an increase in WM test performance and can be transferred to the performance in non-trained cognitive tasks for children, adolescents, adults, and older subjects. Regarding studies conducted on children and adolescents, Klingberg et al.
Westerberg, H. Training of working memory in children with ADHD. Journal of Clinical Experimental Neuropsychology, doi Four months after the six week intervention, the experimental group outperformed the control group in all measurement of working memory categories organization, metacognition, planning, proactivity.
Alloway and Alloway Alloway, T. The efficacy of working memory training in improving crystallized intelligence. Nature Precedings. When compared to the control group, the training group obtained high scores in general knowledge measurements after eight weeks of working memory training. In another study, Jaeggi et al. The training task was a variant of the n-back visual-spatial task used by children with a videogame format. Improving reading comprehension in reading and listening settings: The effect of two training programmes focusing on metacognition and working memory.
British Journal of Educational Psychology, doi Working memory training improves reading processes in typically developing children. Child Neuropsychology, doi School based working memory training: Preliminary finding of improvement in children's mathematical performance. Advances in Cognitive Psychology, 7: 7. Regarding adults and older subjects, Jaeggi et al. The relationship between n-back performance and matrix reasoning: Implications for training and transfer.
Shiran and Breznitz Shiran, A. The effect of cognitive training on recall range and speed of information processing in the working memory of dyslexic and skilled readers.
Journal of Neurolinguistics, doi After six weeks, the experimental group outperformed the control group when measuring working memory, verbal fluency and reading. Unfortunately, Shiran and Breznitz Shiran, A. Similar results were reported in several studies involving young adults Klingberg et al. Working memory plasticity in old age: Practice gain, transfer, and maintenance. Psychology and Aging, doi A potential spatial working memory training task to improve both episodic memory and fluid intelligence.
Improved matrix reasoning is limited to training on tasks with a visuospatial component. Distinct transfer effects of training different facets of working memory capacity. Journal of Memory and Language, doi Working memory training in older adults: Evidence of transfer and maintenance effects. Impact of working memory training on memory performance in old-old adults.
Gains in language comprehension relating to working memory training in healthy older adults. International Journal of Geriatric Psychiatry, doi Is working memory training effective? A meta-analytic review. Developmental Psychology, doi Does working memory training work? The promise and challenges of enhancing cognition by training working memory. Psychonomic Bulletin Reviews, doi Training and transfer effects of executive functions in preschool children.
Developmental Science, doi Adaptive training leads to sustained enhancement of poor working memory in children. Effectiveness of a computerised working memory training in adolescents with mild to borderline intellectual disabilities. Journal of Intellectual Disability Research, doi Cyberpsychology, Behavior, and Social Networking, doi The cognitive training was composed of computerized working memory tasks administered twice a week for two months. Despite an increase in all measurements, no significant differences in fluid intelligence or crystallized were observed between EG and CG.
Chein and Morrison Chein, J. Expanding the mind's workspace: Training and transfer effects with a complex working memory span task. The same result was obtained by Redick et al. Engle, R.
No evidence of intelligence improvement after working memory training: A randomized, placebo-controlled study. Journal of Experimental Psychology: General, doi Chooi and Thompson Chooi, W. Working memory training does not improve intelligence in healthy young adults. The results did not suggest an improvement in general intelligence following repeated training sessions applying a challenging working memory task.
Also, Colom et al. Jaeggi, S. For that purpose, psychology undergraduates completed a battery of twelve intelligence tests and cognitive tasks. There were no significant differences between the trained and control groups for any construct assessed. Studies conducted on older adults that employed working memory training Buschkuehl et al.
Does strategic memory training improve the working memory performance of younger and older adults?. Experimental Psychology, doi In conclusion, there are conflicting results in the literature regarding the real effect of cognitive training based on working memory verses intelligence performance. Considering the lack of studies in developing countries designed to investigate the effects of WM training applied with the purpose of improving intelligence, this study aimed to present findings regarding the effectiveness of working memory training for children compared to intelligence performance.
The average age of the participant sample was of In addition, no differences in socioeconomic levels or parent educational were found. Cognitive Measurements. Two tests were used to measure intelligence in the pre-test and post-tests.
The SPM is the most commonly used non-verbal intelligence measurement in international research aimed at evaluating G f fluid intelligence. In the current study, the Cronbach's alpha was. Kaufman, clinical professor of psychology at the Yale University School of Medicine:. There's no such thing as "an" IQ.
You have an IQ at a given point in time. That IQ has built-in error. It's not like stepping on a scale to determine how much you weigh. The reasonable error around any reliable IQ is going to be plus or minus 5 or 6 points, to give you a 95 percent confidence interval. So, for example, if a person scores , then you can say with 95 percent confidence that the person's true IQ is somewhere between and ; within our science we don't get any more accurate than that.
But as soon as you go to a different IQ test, then the range is even wider, because different IQ tests measure slightly different things. But while there is no single IQ — it's a range of IQs — you can still pretty much determine whether a person is going to score roughly at a low level, or an average level, or a high level. However, IQ is a relative concept.
IQ is how well you do on an IQ test compared to other people your age, and that is true whether you are 4 or in your 40s. It depends. First I think it is important to distinguish between at least three different meanings of the word intelligence. There is biological intelligence, or what is typically defined as neural efficiency. Then there's psychometric intelligence — your measured IQ score — which is an indirect and imperfect method of estimating biological intelligence.
Can you increase biological intelligence? Research during the past decade using various neurotechnologies aka, brain fitness programs has suggested that it is possible to fine-tune your neural efficiency, or mental horsepower. Your cognitive functions can be made to work more efficiently. So can you change your IQ score? Individuals can change IQ scores. Your score may change not because of any real change in general intelligence, but that different tests may be used which measure different mixtures of abilities.
Also, some abilities e.
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