For the picture short-term memory test I was only able to remember 4 objects. I think this test is valid of my short-term memory because I was able to remember a few objects and will remember those 4 things for a short amount of time because I saw the briefly.
For the How is your memory for faces? I would said that the test isn't valid because it comprises so many different parts of the face and mixes them up together. Memorizing faces is generally easy for me even if I have seen a person only once. Since I didn't do as well as I expected I feel this test isn't accurate. I couldn't remember 5 of the face components.
For the Test your memory for an everyday object. I would say that this test is valid because if it something that is used constantly it should be easy to identify. Unfortunately I was unable to recognize the real penny as I was off by 2 of the 4 components. I feel this test is the most valid because it uses things that I will have the most ingrained in my memory.
Here is a cool article about forgetting