The purpose of a cognitive interview is to receive information from the cognitive processes of the interviewee.  The cognitive processes include both covert and overt and observable cognitive abilities (Willis 1999, p. 1). The subjects are often recruited based on the specific characteristics of the survey that was predetermined (Willis, 1999, p.1).

There are two varieties of cognitive interviewing methods that can be used: Verbal Probing and Think-Aloud (Willis, 1999, p.3).  Verbal probing consists of six different types of probing questions.  The desired effects from the verbal probing method are to control the interview and for the training ease of the subject being interviewed (Willis, 1999, p. 6). There are some disadvantages in this method that include the potential for artificiality and bias to occur (Willis, 1999, p.7).

The six verbal probing techniques include posing questions to determine the subject’s ability to comprehend the question, to see if they can paraphrase the question and repeat it back to the interviewer and to determine if the interviewee can feel confident in their ability to judge the meaning of the question (Willis, 1999, p.6).  The next three techniques include testing the subject’s ability to recall the question after a period of time, determine if they can answer in both specific and general forms (Willis, 1999, p.6). 

The second method of cognitive interviewing involves think-aloud.  Think-aloud observes the subjects ability to think while talking and sharing with the interviewer his process of thinking a question to completion.  There are several advantages with this process; the ability to remain free from the interviewer’s bias towards the survey topic, requires very little training for the interviewer to be able to perform this type of interview, and the format is extremely open and a wealth of information can be retrieved (Willis, 1999, p. 4). 

The disadvantages often found when implementing the think-aloud method includes the necessity for the subject to be trained on how to perform the think-aloud answers, the subject could be resistant to the think-aloud process either intentionally or unintentionally (Willis, 1999, p.5).  This process will generally place a burden on the subject to complete the think-aloud process successfully, when in fact the interviewer is only interested in the process not the need for “success” measures.  There is a possibility for the subject to stray from the topic of the survey.  There is an increased possibility for the information to be slanted during the processing of by the interviewer. 

Preparing a proper questionnaire begins when you determine the method you want to utilize.  Whether you are able to find subjects willing to think-aloud or be verbally probe; the success will be determined by the interviewer’s ability to complete and process the information objectively.