# Usability Testing of Mobile Applications:
## 4 Methodological Framework for Mobile Usability Testing
### Data Collection Techniques
#### 4.2.3 Thinking Aloud  
Thinking aloud is the simultaneous verbalization of thoughts during the performance of a task [105]. It is interesting to note that in the literature one can come across two different names that are used as synonyms, namely \"verbal protocol analysis\" or \"talking aloud\" [106]. The basic assumption behind thinking aloud is that, when people talk aloud while performing a task, the verbal stream acts as a 'dump' of the contents of working memory [107]. According to [PERSON] [108], under the right circumstances, i.e., verbally encoded information, no interference, no social interaction, and no instruction to analyze thoughts, it is assumed that such verbalization does not interfere with mental processes and provides a faithful account of the mental states occurring between them.  
According to this view, the verbal stream can thus be viewed as a reflection of the cognitive processes used and, after analysis, provides the researcher with valuable ad hoc information about the user's perceptions and experiences during task performance. In this line of thinking, there are two types of thinking aloud usability tests: concurrent verbalization and retrospective [109]. Specifically, while the former requires participants to complete a task and narrate what is going through their minds, the latter relies on participants to report on their experiences after completing the task. Therefore, one can conclude that, by assumption, the well-known definition of thinking aloud actually refers to concurrent verbalization. Despite its value, analyzing think-aloud sessions can be tedious as they often involve evaluating all of a user's verbalization [110].  
Moreover, different types of thinking aloud involve the verbalization of different types of information. Having said that, the modern literature usually tends to point to two different approaches [111]:  
* Relaxed (or interactive) thinking aloud: a test user is asked to verbalize his or her thoughts by providing a running commentary on self-performed actions and, in moderated tests, is encouraged to self-reflect on current thoughts and actions [112].
* Classic thinking aloud: a test user is limited to verbalizing information that is used or has been used to solve a particular task. In addition, the interaction between researcher and user should be restricted to a simple reminder to think aloud if the user falls silent [113].  
For obvious reasons, [PERSON] and [PERSON]'s recommendations are expected to be followed in unmoderated test sessions. On the other hand, as usability testing practice shows, their guidelines are often relaxed in moderated test sessions, with the aim of eliciting a broader panorama of the user's thoughts and reflections [114].  
The thinking aloud method has become popular in both practical usability evaluation and usability research, and is considered by many to be the most valuable usability evaluation method [115]. Nevertheless, while some researchers have found this method somewhat useful for mobile applications, especially for tasks of relatively low complexity [50], others have appreciated its effectiveness in identifying usability problems [116].