Scientific Content Analysis

How SCAN Works

SCAN analyses are based on written statements. It is important that the statement reflects the examinee's own words. Investigators can transcribe oral statements, but preferably, examinees write their statements themselves because this reduces the risk of their statement being contaminated by the views of the investigator.

Examinees are requested to write down their activities during a certain period of time (for example, “What did you do from the time you woke up until you went to bed?”). They should write their statements in enough detail so that a reader without background information about the examinee's activities could fully grasp the statement. Examinees are asked to write this statement when they arrive for their interview. The investigator is not present when the examinee writes the statement because there is a risk that the investigator's presence may influence the statement. Alternatively, examinees can write their statement at their preferred time and location and return it by mail or fax. The statement needs to be handwritten because one SCAN criterion examines the number of corrections made by the examinee. SCAN can be applied to statements from suspects and witnesses and can be used with adults and children.

The handwritten statement is analyzed by a SCAN expert on the basis of a list of predetermined but undefined criteria. The underlying assumption of SCAN is that true statements, derived from memory of an actual experienced event, differ in content and quality from statements that are based on invention or fantasy. The SCAN method provides no theoretical rationale for this assumption. A SCAN analysis is supposed to give insight into whether the examinee is truthful or deceptive, is trying to conceal something, or was involved in the crime. The SCAN expert uses the SCAN analysis to prepare him or herself for the interview. During the interview he or she will focus on aspects of the statement that raised concern or suspicion.

SCAN Criteria

It is thought that some SCAN criteria are more likely to occur in truthful than in deceptive statements, whereas other criteria are more likely to occur in deceptive than in truthful statements. Examples of criteria include the following:

Social introductions. This refers to how the persons described in the statement are introduced. Truthful social introductions are thought to be unambiguous, for example, “My wife, Lisa.”

Spontaneous corrections. This criterion refers to the presence of corrections in the statement, such as crossing out what has been written. Although explanations and additions are allowed, examinees are explicitly instructed not to cross anything out. A failure to follow this instruction could indicate deceit.

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