Feb 12, 2017


The book Increasing Intelligence can be ordered at the Elsevier Store

1.  The Mystery of Intelligence

Intelligence is a precious asset highly valued in society. It is not surprising that bold claims, which on the one side stress genetic influences on intelligence and on the other side state that it can be raised via cognitive training, cause fierce discussions among scientists and catch the attention of media and the general public. Several hypotheses have tried to explain why in the history of human evolution, no organ has grown faster than the brain. It is likely that a combination of social and ecological factors promoted the proliferation of neural precursor cells, making our brain the most complex organ. Intelligence has been linked to academic performance and career success, therefore in the 20th century much energy has been devoted to the design of preschool and early school interventions that would raise intelligence. In contrast, new age approaches are mainly conducted in controlled laboratory experiments showing promising results, although a definite conclusion is still out of reach.

2.  The Biological Background of Intelligence

Research into the neural underpinning of intelligence has mainly adopted a construct perspective: trying to find structural and functional brain characteristics that would accommodate the psychological construct of g. Few attempts have been made to develop an ability construct exclusively based on brain characteristics. The best neuro-anatomical predictor of intelligence is brain volume as it shows a modest positive correlation with g and explains between 9 and 16% of variance. Larger brains contain more neurons thus they have greater computational power that presumably allows for more complex cognitive processing. Correlations with brain surface, thickness, convolution and callosal shape show less consistent patterns. The development of diffusion tensor imaging has allowed researchers to examine the microstructure of brain tissue. Positive correlations between white matter integrity and intelligence have been consistently observed, supporting the idea that efficient information transfer between hemispheres and brain areas is crucial for higher intellectual competence. Based on functional studies of the brain-intelligence relationship, three theories have been put forward: the neural efficiency hypothesis, the P-FIT and the multiple demand (MD) system theory. The best consensus based on the diversity of results reported is that g is predominantly determined by lateral prefrontal attentional control of structured sensory episodes in posterior brain areas, a model that is also in line with contemporary cognitive neuroscience of working memory.

3.  Raising Intelligence by Means of Behavioral Training

In the last decade a large body of research has tried to provide an answer to the question: Can we increase intelligence? Behavioral studies have provided some evidence that this might be possible, albeit a firm proof is still missing. Most studies that advocate a possible far transfer effect of working memory training on fluid intelligence have various methodological shortcomings that spoil the picture (e.g., no active control group, small sample size). Some optimism that it could be possible stems from the fact that just 20 hours of practicing the n-back task, besides enhancing performance on the task itself, also improves other cognitive processes. In ontogeny 12 years are needed for the development of abstract thinking, whereas some will never reach the stage of epistemic cognition - to know that there are questions that have no correct answer. Hence, if such a brief training experience can change performance on IQ tests it could be speculated that a prolonged one would be even more efficient. Given that training studies are work intensive, time consuming and expensive, we will probably have to wait for this final piece of evidence. From a pure neurocognitive perspective, intelligence is merely a combination of action potentials that, as numerous studies have shown, can be changed.

4.  Changing Brain Activity, Increasing Intelligence: Transcranial Electrical and Magnetic Stimulation

The “Nürnberger Trichter” – a magic funnel used to pour knowledge, expertise and wisdom into students – demonstrates that the idea of effortless learning and the power of intelligence was “cool” even 500 years ago. Today noninvasive brain stimulation (NIBS), which involves transcranial direct and alternating current stimulation (tDCS and tACS), as well as random noise (tRNS) and transcranial magnetic stimulation (TMS), could be regarded as a contemporary replacement for the magic funnel. Currently these methods are not used to boost intelligence, but are regarded as an additional tool that can verify and bring causation into the relations between brain activity and cognition discovered with neuroimaging. Modulating brain plasticity with NIBS and by that changing network dynamics crucial for intelligent behavior is a powerful research tool that can elucidate the neurobiological background of intelligence. However, the mechanisms that contribute to the observed NIBS effects during and after stimulation are at the moment far from understood. Even though NIBS presents a promising approach, it is still at the beginning of its development and time will show whether these methods can serve to explore basic questions in cognition related to brain activity.

5.  Other Approaches: From Neurofeedback to Cognitive-Enhancing Drugs

A number of alternative approaches can affect cognitive function. Presently, there is no evidence that neurofeedback can be used to enhance intelligence in healthy individuals, however, it presents a promising tool for improving specific cognitive processes such as attention and memory. The development of new methods that enable self-regulation of functional connectivity between regions of interest may provide a platform for enhancing performance on tests of intelligence. Research suggests that adhering to a healthy lifestyle, which involves a balanced diet, regular exercise, and stress management, has neuroprotective effects. Moderate intensity physical activity seems to be one of the best methods currently available to promote brain health and counteract age-related cognitive decline. While there is substantial evidence for meditation-related reduction in psychological stress and anxiety and some evidence for improvement in various components of attention, no conclusions can be drawn with respect to its effect on measures of intelligence. Finally, nutrition plays an important role in the child’s intellectual development; multiple micronutrient supplementation to infants and children who have micronutrient deficiencies can improve fluid intelligence. Certain dietary supplements may also help preserve cognitive function in the elderly. The use of drugs for the purpose of improving cognitive functions by healthy individuals raises several concerns with respect to medical safety and ethics. Prescription stimulants can produce short-term improvements in memory and executive function in healthy individuals, however, the long term-effects of the use of cognitive enhancers remain unknown.

6.  Once Upon a Time We Were on the Moon

Does being more intelligent pay off? Counting the pros and cons definitively gives a yes as an answer. Intelligence has made us the dominant species on Earth, with no natural enemies, except ourselves. However, problems from the past such as hunger, poverty and wars have not disappeared. On the contrary, our intelligence has created new ones like pollution, extinction of species, global warming, and population growth, to name just a few. Can a higher IQ solve them?

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