A large amount of the gain in critical-thinking skills stems from an increase in the number of observations that students made in their essays. Students who went on a tour became more observant, noticing and describing more details in an image. Being observant and paying attention to detail is an important and highly useful skill that students learn when they study and discuss works of art. Additional research is required to determine if the gains in critical thinking when analyzing a work of art would transfer into improved critical thinking about other, non-art-related subjects.
The effects of LSD normally last between 6 and 12 hours depending on dosage, tolerance, body weight, and age.  The Sandoz prospectus for "Delysid" warned: "intermittent disturbances of affect may occasionally persist for several days."  Contrary to early reports and common belief, LSD effects do not last longer than the amount of time significant levels of the drug are present in the blood. [ citation needed ] [ contradictory ] Aghajanian and Bing (1964) found LSD had an elimination half-life of only 175 minutes (about 3 hours).  However, using more accurate techniques, Papac and Foltz (1990) reported that 1 µg/kg oral LSD given to a single male volunteer had an apparent plasma half-life of hours, with a peak plasma concentration of 5 ng/mL at 3 hours post-dose.