Previous research from earlier this year found that people can even erase emotional memories from their brains.
The finding, published in the journal Psychological Science, came from a study which showed that throwing their thoughts away in the trash allows people to toss out those thoughts in their mind as well. However, if people kept the piece of paper in their pocket to protect it, they had a higher chance of using their thoughts to make judgments.
"However you tag your thoughts - as trash or as worthy of protection - seems to make a difference in how you use those thoughts," explained Richard Petty, co-author of the study and professor of psychology at Ohio State University.
Variations of this concept are used in certain kinds of psychological therapy by having patients try to mentally discard their unwanted thoughts. However, until now, no research had confirmed this strategy, according to Petty.
"At some level, it can sound silly. But we found that it really works - by physically throwing away or protecting your thoughts, you influence how you end up using those thoughts. Merely imagining engaging in these actions has no effect."
The results indicate that thoughts can be dealt with as solid objects, which is obvious in how we speak. "We talk about our thoughts as if we can visualize them. We hold our thoughts. We take stances on issues, we lean this way or that way. This all makes our thoughts more real to us." Petty added.
Three experiments were conducted in this study by Petty and her colleagues, Pablo Briñol, Margarita Gascó and Javier Horcajo, all of the Universidad Autónoma de Madrid in Spain.
There were 83 high school students from Spain involved in the first trial, which they believed was about body image. The subjects were given three minutes to write down either positive or negative thoughts about his or her body.
They then had to look back at what they had written down. Half of the participants examined their thoughts and then threw the paper away in the trash, "because their thoughts did not have to remain with them." The other group had to look at their thoughts and then see if they made any spelling or grammar mistakes.
Next, the students were asked to rate their attitudes on their bodies on three 9-point scales: like-dislike, bad-good, unattractive-attractive.
The experts discovered that whether the participants had negative or positive thoughts made a difference for those who kept the paper and looked for errors. After a couple of minutes, the people who wrote down positive comments had better attitudes about their bodies than those who wrote negative comments.
The students who tossed their thoughts into the garbage showed that those thoughts had no influence in how they rated themselves, demonstrating that whether they wrote down positive or negative feelings did not matter.
"When they threw their thoughts away, they didn't consider them anymore, whether they were positive or negative," Petty said.
The second experiment involved 284 students who were asked to write either negative or positive thoughts about the Mediterranean diet. Most people consider this diet to be good, it stresses the importance of consuming large amounts of veggies, fruits, legumes and unrefined cereals, with the basic fat as olive oil.
The participants either left the paper on their desk, threw the paper in the trash, or put the paper in their pocket, purse, or wallet so they protect it.
Their attitudes toward the diet were rated by all subjects, and they were also asked how likely they were to use the diet.
The results were similar to the first study. The people who had their paper at the desk showed to be more influenced by them in their evaluations about the diet compared to those who threw the paper in the trash.
On the other hand, the subjects who kept their thoughts protected in their pocket or wallet were even more influenced than those who had the paper on their desk.
Participants who put their positive thoughts about the diet in their pocket, the authors explained, gave the diet better ratings compared to those who kept their positive thoughts on the desk. The people who kept their negative thoughts in their pocket had more negative ratings for the diet than those who kept their thoughts on the desk.
"However you tag your thoughts - as trash or as worthy of protection - seems to make a difference in how you use those thoughts."
"This suggests you can magnify your thoughts, and make them more important to you, by keeping them with you in your wallet or purse," said Petty.
Is the physical action of throwing these thoughts away important?The third trial was conducted using computers in order to answer this question. Seventy-eight college students from Spain were asked to write their thoughts in a word-processing document on a computer. Half the students dragged the file into the recycle bin on the computer and the other half saved the file on a storage disk.
The results showed exactly what the team had anticipated. When subjects dragged their negative thoughts into the recycle bin, they made less use of them, compared to the people who saved the thoughts on a disk.
The students were also told in a different task to just imagine them dragging their negative thoughts into the trash on the computer or saving them to a disk. This, however, had no impact on their judgments later on.
"The more convinced the person is that the thoughts are really gone, the better. Just imagining that you throw them away doesn't seem to work.
Of course, even if you throw the thoughts in a garbage can or put them in the recycle bin on the computer, they are not really gone - you can regenerate them. But the representations of those thoughts are gone, at least temporarily, and it seems to make it easier to not think about them."
The team plans to conduct further research in order to determine whether this method could be used to help people who struggle with recurrent negative thoughts, such as thoughts about a love one who has passed.
"It is often difficult to get rid of these thoughts. We want to find out if there is a way to keep those thoughts from coming back, at least for longer periods of time." Petty concluded.
Written by Sarah Glynn