I have just completed some work for ITN, a UK TV producer, and we will be highlighting on Channel 5 (August 2017) how the psychophysiological signals gave away Stuart Hazell during a press interview where he was trying his best to disguise his involvement in the horrific murder of his step-granddaughter, Tia.
While biometric indicators of what the Autonomic Nervous System (ANS) is doing often need technical equipment and biometric sensors to pick them up, there are many clues from behaviour and appearance that can point to these changes.
Let’s first lay out the Psychophysiology elements that are of interest to a Behaviour Analyst: Heart rate, Perspiration, Temperature, Blood pressure, Breathing, Digestion, and Pupils.
Recent technological innovations and advances mean that it should be possible to incorporate tools, within behaviour analysis work, which provide ANS information beyond the physiological signals which can be seen/heard. I recognize that most of these measure stress or anxiety (not necessarily deception or malintent) though we are currently experimenting with data collection tools that can be fed into a ‘hypothesizing-human-decision-maker’ including:
- Thermal cameras to help users to ‘see’ local blood circulation in others
- Laser doppler vibrometers that can measure blood pressure and heart rate variability from 50 meters away from the subject (used in military triage in enemy territory)
- Pixel movement/colour changes(amplified by a factor of a hundred) so that users can pick up skin colour changes and movement/micro-expressions that the naked eye may not (including, a pulse)
- Multichannel polygraph equipment
- ‘Kinect’ type technology – used in computer gaming – to pick up the slightest body movement
- Remote pupilometry which is making advances into indexes of cognitive/emotional activity and load.
The above bring challenges, as well as potential benefits. Overt technology can create behavioural changes which contaminate evaluations, as we know from the criticisms around the field of polygraphy (National Research Council, 2003). The ethics and practicalities of using covert equipment complicate real-world analysis – so I would rather take the easier approach and avoid contamination with such gadgets.
In addition, if/when it becomes possible for users to have access to the data picked up by such tools during real-time (as opposed to post-event) analysis, we will need to consider whether simultaneous data-overload might lead to a deterioration of performance in users’ real-time assessments across the six communication channels we consider. This needs more research.
A related issue is achieving buy-in from professionals (working in high-stakes contexts) who have limited time and capacities to capture simultaneous, multimodal data from a human; especially when they are working alone. With challenging base-rates (large volumes of innocent people compared to the low volume of people with mal-intent) and long working shifts, we are coaching staff to ‘reset’ their attention for every person with full attentiveness. Staff may also be restricted (by ethics, protocols, legislation, etc.) from using covert or overt technology. This includes police, military personnel, security professionals, HR screeners, recruiters, negotiators, medics, purchasers, social workers, and so on.
All is not lost with biometrics, however, especially when we look at what our natural senses can detect:
- Some people have prominent carotid arteries or veins on their temples or centre forehead which can highlight increases in blood pressure. I know… this sounds geeky, but just watch actress Julia Roberts’ centre forehead vein when she becomes stressed, angry or fearful in her movie roles. Of course, like other data in this channel, we need to work out which of these she is feeling and check it against the ABC (Account or story she is telling, her Baseline behaviour, and the Context of the interaction) before we can mark it as a ‘Point of Interest’ (PIn) – and we need a 3/2/7 Cluster (three of these indicators across two channels within seven seconds of a stimulus/question) before we get excited.
- The fight(anger) or flight(fear) states can also cause the digestion system to cease as the sympathetic nervous system kicks in. The stress response releases epinephrine (or adreniline) into the body and this brigades resources towards the essential organs (heart/lungs/muscles) as the body is primed to respond to whatever triggered those states. The digestion system isn’t needed in these moments, and thus the stomach and salivation functions wind down, often leaving the mouth dry. The clues that this is happening are in the increased swallowing, lip-licking, and water-sipping, as seen from nervous public speakers and liars. If it is inconsistent with the ABC… it’s a PIn.
- Perspiration can be seen as a change in the glow on a forehead or the change in dampness in a hand-shake before during and after an interview. Take care again, here, as warm rooms, flu, anxiety, fear of being disbelieved, and deception are all possible, and these need testing with good probes.
- Breathing rate changes are quite easy to see and the stopping of breathing is common in fear, with shorter breaths in the upper chest being a possible signal of anger or fear. If the change is out of context, then this is a Pin.
- Warm faces can signal anger; cold faces can signal fear. In some skin tones this can be seen as a skin colour change. This is caused by changes in local blood flow away or towards the extremities, ears, nose and the skin surface.
- Pupil size is affected by cognitive and emotional load though this is a complex area and very hard to monitor in conditions where lighting isn’t constant. We also need to consider that the person of interest may be under the influence of drugs or medicines and it can be very difficult to see changes with those people who have a dark brown iris. I include it on the PIns list, though, since pupil dilation and contraction is very difficult to consciously control. I feel pupils will play an increasing role in the data-mix as biometric measures on webcams, and in airports and security contexts, move forward.
Before I wrap up this section, you may wish to review a 13-second clip from an example of a video clip from the Hazell case. This is Stuart Hazel, partner of Tia Sharp’s grandmother who was staying in their home. Six days before this news interview Tia was reported as missing, and Hazel was asked to help with an interview to appeal to the public for help in finding her.
Hazel was the last to see her alive and reported that Tia had left the house, alive and well, to go into a local town. See what physiological (and other) indicators you can notice from the short clip labelled VIDEO 7 at www.gettingtothetruth.com.
Make notes about what you hear and add them to this blog. I will input our thoughts once a few people have contributed.
p.s. (The truth is that throughout this interview the body of Tia was hidden above their heads in the attic. Hazell was found guilty of Tia’s murder and is serving 38 years imprisonment for his crime).