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PhD Defence

Cognitive enhancement: Toward the integration of theory and practice

Thursday 16 June 2016
Academy Building
Rapenburg 73
2311 GJ Leiden

The research described in the thesis was supported by a research grant from the Netherlands Organization for Scientific Research (NWO) awarded to Lorenza S. Colzato (Vidi grant #452-12-001)


Cognitive enhancement reflects the use of any (legitimate) means such as for example food supplements to reach one’s personal best, and has gained great interest over the past years. The increasing costs of welfare offer one explanation, the second is that both Eastern and Western societies are continuously driven toward more individualism pushing the idea that an individual is the director of his or her own life. Together, this has led to an increase in interest in activities and procedures that help to express individual needs and develop strategies in order to deal with this.

With my research, which was supported by an NWO VIDI grant awarded to my supervisor Dr. Lorenza Colzato, I attempted to explain how and why enhancement techniques such as brain stimulation, videogaming, and food supplements (e.g. tyrosine and tryptophan) can offer promising and inexpensive ways to enhance cognition. I demonstrate, for example, that food supplements can offer a healthy method to enhance (social) cognitive functioning, and that in a way “we are what we eat” (Feuerbach, 1864).  

Clear ideas about the underlying mechanisms of these effects are needed before these techniques can be applied outside the field of science. That is, we have to be careful in applying these techniques and methods to ourselves without yet knowing how  they work. For example, in one of my studies, I found that a commercial brain stimulation device actually had detrimental effects on cognitive performance with regard to working memory. This can be explained by the fact that we do not yet know which factors contribute to the observed effects, and in what ways these factors influence performance. Hence, although these techniques offer promising ways to enhance performance, I do agree with a recent claim made by prominent researchers: The scientific community needs to become more active in order to gain better insights into the underlying mechanisms and factors modulating the observed effects within the field of cognitive enhancement – especially concerning claims made by the brain-training industry.
These findings have important societal and economic implications and go hand-in-hand with the ideological individualistic trend. That is, the discussed techniques do have promising potential, not only in enhancing (social) cognitive functioning and mental well-being in healthy humans but also in possibly delaying (social) cognitive decline in elderly – the latter representing my research focus in the near future.


  • Prof. S.T. Nieuwenhuis


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