Verbal Protocol Analysis


A verbal protocol analysis (VPA) is a think-aloud method of eliciting cognitive and physical process descriptions from a user. The descriptions are of processes that are performed by the user to complete a specific task.


To gain cognitive insight into complex behaviors.

How do I use this tool?: 

1. DEFINE SCENARIO UNDER ANALYSIS. Consider using a hierarchical task analysis (HTA) for this step.

2. TRAIN THE PARTICIPANT. Brief them about what they need to do during the analysis. Ensure they understand what they need to report verbally and that they understand it is important for them to keep talking even if they do not think what they are saying will make any sense. Consider demonstrating this process to the participant.

3. BEGIN SCENARIO AND RECORD DATA. Use audio recordings and consider using video as well.

4. VERBALIZATION OF TRANSCRIPT. Transcribe and review the data.

5. THE TRANSCRIPTS SHOULD THEN BE CODED into categories or themes. The analyst should create a universal set of instructions that will be referred and adhered to throughought coding.

6. Once the coding is complete, DEVISE ANY ‘OTHER’ DATA COLUMNS. This should be done by the analyst to account for any extraneous circumstances affecting the transcript.


8. PERFORM PILOT STUDY. Look for problems and iterate the procedure.

9. ANALYZE STRUCTURE OF CODING. Analyze the results from the VPA. Add the frequency of each occurrence in each category.

Expertise Required: 
This tool is an advanced tool and requires formal training or education.
Recommended Supplies/Materials: 
Spreadsheet software (for categorization)
Video recording equipment

Provides means of fully understanding the work of an individual or work related to a particular task(s).


Each scenario will be different. The objective must be clearly stated to result in meaningful analyses.

Is time consuming to capture and analyze information.

Other simpler techniques may capture similar information (although possibly not as "rich").

Where can I go to learn more?: 

Stanton N, Salmon P, Walker G, et al. Task analysis methods. Human factors methods: a practical guide for engineering and design. Great Britain: Ashgate; 2005. p. 45-76.