Scott Fraser studies how humans remember crimes -- and bear witness to them. In this powerful talk, which focuses on a deadly shooting at sunset, he suggests that even close-up eyewitnesses to a crime can create "memories" they could not have seen. Why? Because the brain abhors a vacuum. Editor's note: In the original version of this talk, Scott Fraser misspoke about available footage of Two World Trade Center (Tower 2). The misstatement has been edited out for clarity.