June 27, 2016 at 03:13AM

Today I Learned: 1) Here's an interesting new form of accidental racism -- racist machine learning algorithms are more common than you'd think. Example: about a year ago, Google's automatic image-tagging algorithms would identify pictures of black people as gorillas. There have been at least two instances where camera software didn't work on non-whites (Nikon's software thought Asians were blinking, and HP's had trouble with dark skin). Why? Almost certainly it's an issue of not having enough non-whites in the training data, but it's hard to know with complete certainty. But wait! It gets worse! It turns out that a lot of police departments in big cities use predictive algorithms for forecasting crime hotspots. Since those algorithms use past data, and minority neighborhoods are almost universally patrolled and criminalized more heavily than white neighborhoods, that software is much more likely to assign *yet more* policing to places already discriminated against. Similar problems exist for software used in predicting individual risk of criminal activity. Then there's an example from Amazon, which isn't actually a racist machine learning algorithm so much as racist policy, where Amazon denied same-day deliveries to majority-black neighborhoods for some time. And, of course, there are sexist AIs too. For example, here's a (non-paywalled) article on google ad tracking in which the authors accidentally discovered that women are much less likely (about 1/6 as likely) to receive adds for high-paying (>$200k/year) jobs than men. It's not clear whether this is due to some subtle effect of google's ad-matching software or some explicit policy on behalf of any of the many agents at play in the online ad marketplace. This TIL is essentially a distilled version of this article from the NY Times: http://ift.tt/29eRoQb. The only real problem I have with the article is the author's relative dismissal of existential risks of AI. I realize that racist algorithms are a problem *right now* and should be addressed, but comparing racism to the possible extinction of the human race is a bit appauling. 2) Stomachs are much higher in the body than I thought. They're actually held *within* the ribcage, held right up against the lungs. This fact brought to you by Kevin Cherry. 3) ...some of the differences between extruded and cast acrylic plastic. Cast acrylic is made by mixing the right chemicals inside a mold, which harden into a hard plastic. Extruded acrylic is made with a similar mixing, but instead of being made inside a mold, the plastic is forced through a pair of rollers or another thin channel, which makes it come out as a sheet. Cast acrylic is generally considered "better", largely because a) it is harder to deform and b) because it has the same physical properties in every direction. Extruded plastic is a bit more warpy, and has different properties on the axis on which it was rolled than in the other direction. Cast acrylic also comes out with smoother edges when laser-cut, and the two plastics turn different colors when engraved.