Researchers from the University of Cambridge published a study of these two ways in a paper today, Oct 17, in the journal Neuron.

"This study is the first demonstration of two distinct mechanisms that cause such forgetting: one by shutting down the remembering system, and the other by facilitating the remembering system to occupy awareness with a substitute memory," study researcher Roland Benoit said in a statement from the journal.

The researchers studied 36 individuals that were asked to remember word pairs like "beach Africa." They were then told to forget the word pairs using one of two methods: Half the participants were told to just forget the word "Africa" while and the other half were supposed to substitute "Africa" for the word snorkel.

The researchers scanned the participants brains using a functional MRI to measure brain activity while they were actively forgetting. They found different, distinct brain activity for the two different forgetting approaches.