Here are the results from four classes that took the test. The curves show the percentage of students that recognized the quantity shown on the slide correctly. Blue curves are from classes of people 65 years of age and older, red curves are from classes of high school students. The n values indicate the sample size (people in each class).
The results show that virtually all students recognize quantities up to 4 or 5 correctly. (The high school students were less organised than the senior students; some missed the first few slides, which explains their performance slightly below 100% for small quantities.) For larger quantities the success rate falls off rapidly irrespective of age.