What is the improvement curve of all other forms of human intelligence enhancement, such as smart drugs, brain-computer interfaces, implants, augmented reality, and neuroengineering? That is, what multiplier will they confer to scientific progress in the world as a whole?

• Claim: The human brain has already been highly optimized by evolution, and making further improvements is likely to be very difficult. There is evidence that certain neurological diseases, such as schizophrenia, are in fact by-products of our large and metabolically hungry brains. Further "improvements" to the brain may produce so many dangerous side effects that they are untenable. Furthermore, restrictions on human experimentation will radically slow human intelligence enhancement research. Improvements not based on biology are likely to yield relatively small progress gains.
  Implication: Slow improvements over the course of the century, driven primarily by factors such as improved interfaces and usability.
  Sources: Baldwin, Graeme. "Human brains pay a price for being big." EurekAlert. 4 Aug. 2008. <http://www.eurekalert.org/pub_releases/2008-08/bc-hbp080108.php>.
  Smart, John M. "Limits to Biology." Acceleration Watch. 2008. <http://www.accelerationwatch.com/biotech.html>.

• Claim: Though biological and pharmaceutical interventions are likely to be held back both by the inherent difficulties of biology and restrictions on human experimentation, better computer interfaces and displays, including augmented and virtual reality, and eventually mind uploading, are likely to accelerate scientific research as they are adopted.
  Source: Smart, John M. "Acceleration Watch." Acceleration Watch. 2008. <http://www.accelerationwatch.com/biotech.html>.

• Claim: Significant enhancements to human intelligence through biological and pharmaceutical interventions are plausible, and are likely to cause significant acceleration of scientific research in coming decades. These, coupled together with better interfaces, give us reason to expect large gains. The finding that 20% of scientists take performance-enhancing drugs for non-medical reasons, even when these drugs are just in their infancy, shows how much demand there will be when these drugs work even better.
  Implication: Productivity gains by a factor of 10 or more, with ramp-up beginning almost immediately.
  Source: Bonifield, John. "Use of brain-boosting drugs reported in survey." CNN Health. 9 Apr. 2008. <http://www.cnn.com/2008/health/04/09/brain.drugs/>.
  DeNoon, Daniel J. "Poll: Scientists Use Brain-Boosting Drugs." WebMD. 9 Apr. 2008. Retrieved 9 Aug. 2008 <http://www.webmd.com/brain/news/20080409/poll-scientists-use-brain-boosting-drugs>.

• Claim: Science could be significantly accelerated by changes in the infrastructure of science and better software, like a superior version of Google Scholar or other better intelligence "glue".
  Implication: Productivity could expand by a factor of 2 to 10 by improvements not to the structure of human intelligence, but in the way that researchers interact and organize their time and resources.
  Source: Various.