Many interviewers believe that they can pick up these cues and tell whether the suspect is lying. However, scientific research has revealed that such lie detection accuracy is often not much better than chance guesses. Some researchers suggested that the main reasons for the inaccurate prediction rests in the lack of knowledge about human physiology and psychology and the lack of intensive training in observation and interviewing.

To detect hot spots, interviewers need to understand that the physiological and behavioural changes can also occur when a person is not lying or when the person is thinking of other emotional issues. Moreover, some people's responses can be very obvious while others rather subtle. The interviewer therefore needs to know the 'normal' patterns of the particular suspect. In other words, what would be his responses and behaviour when thinking or talking about non-crime or other emotionally sensitive issues? This can be done by first engaging the suspect in innocuous conversation and carefully observing his behaviour. With that as a baseline, sensitive questions can be asked and the interviewer will be able to decide more confidently whether or not the subject has a hot spot to hide.

However, accurately detecting hot spots does not mean the suspect is lying. The hot spots only tell which issues are particularly sensitive to the suspect. The interviewer has to probe for more details to understand why the suspect is avoiding the topic. Without the curiosity follow-up, there is no way the interviewer can tell more about this suspect. So, instead of detecting lies, the interviewer is actually trying to understand the mind of the suspect in the interview.

For further information about forensic and criminal psychological competency, you can contact the Police Clinical Psychologist of Child Protection Policy Unit at 2804-1437.

Stress management workshops

The PSG is organising a series of stress management workshops to be conducted in Chinese. The next one is at the Police Sports & Recreation Club Art Room on March 15 from 8.45 am to 12.30 pm. Participants are requested to arrive 15 minutes before the programme starts. Thirty places for each session will be allocated on a first-come-first-served basis. To make a reservation contact PSG at 2866-6207.

Seek advice and help from the Psychological Services Group:

PHQ, Hong Kong Island and Marine: 2866-6206 (5/F, 111 Leighton Road, Causeway Bay); Kowloon and the New Territories: 2735-3739 (22/F, Ocean Building, 80 Shanghai Street, Kowloon). PEN: psg@police.gov.hk