A mental block is an uncontrollable suppression or repression of painful or unwanted thoughts/memories. It can also be an inability to continue or complete a train of thought, as in the case of writer's block. In the case of writer's block, many find it helpful to take a break and revisit their topic. Another tactic that is used when people with mental blocks are learning new information is repetition. A similar phenomenon occurs when one cannot solve a problem in mathematics which one would normally consider as simple. Mental blocks can be caused by physical disabilities or simply a lack of focus. Mental blocks are also often used to describe a temporary inability to recall a name or other information. A sudden cessation of speech or a thought process without an immediate observable cause sometimes can be considered a consequence of repression. Incidental forgetting Forgetting curves could be associated with mental blocking. The forgetting curve was first described by Ebbinghaus as the natural loss of memory retention over time. Memories can also simply disappear over time from Trace decay which is the weakening of memories over time. This kind of decay stems from both the visual and verbal working memory. Although this triggers decay, some of the information remains stored. Interference is the phenomenon that a memory can be distorted due to the existence of related memories when it comes to retrieval. Although incidental forgetting is unintentional, it is an important process. A person's brain can become overwhelmed with information, so it is beneficial when unneeded stored information is forgotten. Two interferences are associated with incidental forgetting, proactive and retroactive. Proactive interference is the effect on a person's ability to recall information on a learned subject. An example of this would be a person having trouble remembering a friend's new address when they had the old addresses memorized. Retroactive interference is when new learning affects one's memory on a previously learned task. An example would be an actor learning new lines for an upcoming episode they are filming. When they are learning the new script, this could affect their ability to remember the script that went along with the previous episode. Another interference that some scientists believe is the main culprit of incidental forgetting is one's ability to pay attention which therefore hinders one's brain's ability to properly encode the learned information. A noteworthy cognitive research study showed study participants