Show group of eight elements, mark down some of them, get information about marked

Hi.

Currently I developing following test of working memory:

  1. I show a series of symbols (one at a time about 0.4-1 seconds each) to subjects and they have to remember them.
  2. Then I show a group of eight items and asked to remember which of those eight they just already saw in the sequence.
  3. The subject must mark down (preferable via using mouse) items that were in the series and then I will calculate all that I need.

Question: What kind of PsychoPy objects you can recommend me to use for showing group of eight elements and getting information about pressed items?

OS: Linux
PsychoPy version: 3.1.3