Inkblots should not be used in psychology. There are many reasons that I believe this, however I will only cover a few.
What we see is what we see:
It's as simple as that. Lets say a person is having an outdoor party and they look out the window to see if it's going to rain. Out of the corner of their eye they see a cloud that looks like a bunny. Another person goes out to check their mail that day and they see a cloud that looks like a scary face. Both of those people just saw a shape and went, "Hey, that looks like a..." and that fact said nothing about who they are as people. Most of us already know that what we see in something does not determine who we are.
A vase or two faces:
There is an illusion called Rubin's vase. Lets say that the vase in the picture is white and there is black around it. If you look at the white portion of the picture it is a vase. If you look at the black part it's two faces looking at one another. The first time a person looks at an illusion like this they only see one part of it. Everyone is different however. It is just how a person perceives it. I believe the same can be said of an inkblot.
Did you know that two people standing next to each other in front of a rainbow do not see the same rainbow? It is how each of our eye sights view it. Every eye is different and no one sees the same thing. Inkblots and illusions are the same way.
Inkblots are a way of guessing something about someone. Most of the time psychologists put their thoughts and feelings onto someone else unknowingly. Inkblots become more about the psychologists themselves than with their patients. Time is better spent getting someone to open up than to try to uncover a "mystery" about a person. A magic eight ball would be more accurate and a lot faster.
Determining who someone is:
I overheard my roommate's girlfriend, who is on her way to becoming a psychologist, talking about how inkblots are used to figure out whether a person is a killer or sex offender. I started thinking about all the things that are wrong with that.
Did you know that men have accidental erections throughout the day? Does that mean that if a man sees breasts in an inkblot that he's perverted? For all we know his wife has been withholding sex from him for months because he forgot to fix the icebox. Plus, men have sex oriented minds. To top it all off, the guy seeing breasts could just be very immature and comedic. If you see blood spatter in a inkblot you might just be a huge fan of the tv show Dexter. Maybe you're a writer or an artist and you're just very imaginative. Which means that if you don't tell your psychologist that you're creative, a horror movie/tv lover, or that you haven't had sex in awhile then they could interpret it in a bad way. What I see from that is that they can be very wrong and judgmental about something that has nothing to do with anything.
Last, but not least, is memory. A week or so ago, when I overheard the discussion of inkblots, I looked up an inkblot test and took it. I thought one picture looked like Mothman from The Mothman Prophecies. I've never even seen Mothman, yet I vaguely remembered a picture of him from a trailer or box art of some kind. But since I saw Mothman in the inkblot, did that say anything about me whatsoever? No, not really. I think back on it and it means nothing to me other than a memory I had. My mind came up with what it saw and it was nothing more than that. If a killer in prison sees a dragon tattoo on another inmate in jail, takes an inkblot test a few days later, and then sees a dragon in the inkblot what does that mean? Absolutely nothing other than remembering something he saw.
Some psychologists still use inkblots as a way of learning someone's personality. I think that the time it takes them to do that is better spent asking the patient to draw a picture or write something. A lot more would come of it than something like an outdated test. The Rorschach inkblot test is fun and entertaining, but there is nothing truly scientific about it.