a person needs to send an e-mail attachment, and asking them to undertake this task. The aim is to observe how people function in a realistic manner, so that developers can identify the problem areas and fix them. Techniques popularly used to gather data during a usability test include think aloud protocol, co-discovery learning and eye tracking. Hallway testing Hallway testing, also known as guerrilla usability, is a quick and cheap method of usability testing in which people — such as those passing by in the hallway — are asked to try using the product or service. This can help designers identify "brick walls," problems so serious that users simply cannot advance, in the early stages of a new design. Anyone but project designers and engineers can be used (they tend to act as "expert reviewers" because they are too close to the project). This type of testing is an example of convenience sampling and thus the results are potentially biased. Remote usability testing In a scenario where usability evaluators, developers and prospective users are located in different countries and time zones, conducting a traditional lab usability evaluation creates challenges both from the cost and logistical perspectives. These concerns led to research on remote usability evaluation, with the user and the evaluators separated over space and time. Remote testing, which facilitates evaluations being done in the context of the user's other tasks and technology, can be either synchronous or asynchronous. The former involves real time one-on-one communication between the evaluator and the user, while the latter involves the evaluator and user working separately. Numerous tools are available to address the needs of both these approaches. Synchronous usability testing methodologies involve video conferencing or employ remote application sharing tools such as WebEx. WebEx and GoToMeeting are the most commonly used technologies to conduct a synchronous remote usability test. However, synchronous remote testing may lack the immediacy and sense of "presence" desired to support a collaborative testing process. Moreover, managing interpersonal dynamics across cultural and linguistic barriers may require approaches sensitive to the cultures involved. Other disadvantages include having reduced control over the testing environment and the distractions and interruptions experienced by the participants in their native environment. One of the newer methods developed for conducting a synchronous remote usability test is by using virtual worlds. Asynchronous methodologies include automatic collection of user's click streams, user logs of critical incidents that occur