# Implementation and Evaluation of a Serious Game for Working Memory Enhancement
## 2 Theoretical Background
### Working Memory Training  
WM's capacity is not fixed, but rather depends on and is defined based on what one is able to remember. Recent research shows that the capacity of WM can be increased through certain and targeted training. Considering the strong relationship between WM and higher cognitive skills, recent studies have focused on the capacity's alterability, which in turn has led to results indicating that the training of the WM generates benefits reflected in the cognitive functions of the human brain. This is another key factor which dictates the ongoing need for WM training. There are two main approaches in WM training, basic and strategic, and there are underlined theoretical and practical incentives which lead to each one of them. Increasing WM's capacity by certain training has been accepted and utilized in recent years, presenting encouraging and positive results in many different groups of people. However, it should be noted that each approach leads to different outcomes, and we should not expect that following one or another will positively affect every cognitive function. Nevertheless, there have been certain studies with encouraging results towards a targeted and holistic training approach, which can lead to an overall improvement of cognitive skills. However, there are still certain boundaries that we have to overcome in order for these studies to be accepted by the scientific community. Memory can be treated like the human body; just like the human body needs regular and systematic training and exercise, memory should also be trained in a way that will guarantee its top performance. The only aspect of WM that can be improved is its capacity. Unfortunately, regarding the time period that information can be preserved, there is not much that can be done in the form of a training program, apart from more repetitions. These repetitions will eventually result in the storage of information in the long-term memory so that it can remain there for more time. Time is specific, but capacity has several ways of improvement. Memory enhancement methods include basic and strategic training, mnemonic strategies like rehearsal--the conscious repetition of information to be remembered [22], chunking--organizing information into manageable bits or chunks [23] or building mental images for information encoding [24]. In order to attain memory decongestion, we can utilize management, memorizing techniques, connection, cognitive load reduction, a record of stressful situations and the capability of reducing interferences. Therefore, for WM to be enhanced we can use the same techniques that we exploit for memory enhancement. The simplest strategy, according to [PERSON] and [PERSON] [25], is the repetition of information, which allows us to strengthen WM and is suitable for people with low WM such as, for instance, the elderly. On the other hand, regarding WM decongestion techniques as mentioned above, they intend to free space for WM to function better--it is not all about increasing WM capacity. We can achieve the same results by freeing space for WM. Of course, besides the abovementioned methods for the enhancement and decongestion of WM, corresponding drugs have also been developed which help to improve brain functionality, such as bromocriptine, which affects dopamine receptors [26]. Furthermore, another method constitutes the intervention in the way the neurons of the human brain function as shown in a recent study by [PERSON] and [PERSON] [27], in which they managed to restore the memory of a group of elderly people for a limited time period (50 min). Certain interactions between neurons are part of WM functionality, which in turn managed to recover to a level as in the age of 20 years old with electric stimulation. From these findings, we can conclude that the intervention method for WM enhancement varies from case to case and depends on the group of people we attempt to treat.