Cognitive performance under challenging circumstances.
Submitting InstitutionUniversity of Winchester
Unit of AssessmentPsychology, Psychiatry and Neuroscience
Summary Impact TypeSocietal
Research Subject Area(s)
Medical and Health Sciences: Clinical Sciences, Neurosciences
Psychology and Cognitive Sciences: Psychology
Summary of the impact
Dr Kneller's research on cognitive performance under challenging
circumstances demonstrates impact in two areas:
1) Informing practice in diving. Kneller's research has demonstrated the
effects of nitrogen narcosis on memory, and how anxiety may compound its
severity. This has implications for recreational, commercial and military
diving and has been recognized by diving industry sources.
2) Improving eyewitness identification within the context of crimes.
Kneller's research has informed practice in the process of eyewitness
identification for victims of crime. Her findings have impacted on
policing practice in terms of how suspect line-ups are conducted and her
expertise recognized within practitioner circles.
Kneller's research on cognitive performance when diving has significant
implications for safety and diving practice. One of the biggest hazards
facing divers is nitrogen narcosis, the temporary alteration in
consciousness caused by breathing compressed air when descending below
30-40 metres. Impairments to judgement and decision-making affected by
this state pose considerable hazards for professional divers, particularly
those engaged in technical activities. The research aims to better
understand which cognitive mechanisms are affected by nitrogen narcosis,
and how narcosis interacts with anxiety. The aim is also to provide
guidelines on how to help divers recognise when they may be under the
effects of narcosis, to reduce work place accidents and fatalities, and to
develop practical methods by which to reduce the effects of narcosis in
divers when undertaking tasks underwater.
The underpinning research consists of four studies. This work was
conducted in collaboration with Dr Malcolm Hobbs, owner of West Bay Divers
in Honduras. The first (Hobbs & Kneller, 2009) explored
narcosis-induced memory decrements to understand at what time performance
may be impaired. The second study showed that anxiety (especially in
novice divers) exacerbates performance deficits presumed to be caused by
narcosis (Hobbs & Kneller, 2011). A third study was funded by the
Professional Association of Diving Instructors (PADI) Foundation. It
developed and tested a novel, more transportable and inexpensive physical
dexterity task with which to test divers' manual dexterity and psychomotor
performance (Kneller, Higham & Hobbs 2012). The fourth study used an
established levels-of-processing approach and found that narcosis affects
both encoding and retrieval processes (Kneller & Hobbs, 2013). These
findings suggest that divers engaged in effortful cognitive tasks under
water (such as locating and memorising details about mines) would benefit
from strategies which lessen narcotic memory impairment.
Kneller's research in eyewitness testimony also provides useful insights
into cognitive performance under another type of challenging condition:
that involved in gathering information from victims of crime. The research
relates to procedures by which identification evidence is gathered by the
police from witnesses to crimes. When a victim of crime is identifying a
suspect, they are doing so in a usually very charged and emotional
circumstance and accuracy of their subsequent recall is critical.
Kneller's research here follows on from her PhD which resulted in a
seminal publication on the accuracy of sequential vs. simultaneous line-up
procedures (Kneller et al., 2001), which itself has been cited 41 times in
PsycINFO as of 28/03/2013. Dr Kneller has continued with this research
programme to investigate the veracity of video line-up procedures used by
forces in England and Wales, and the use and effectiveness of the optional
`matrix' presentation, a component of the Promat line-up system (a common
eyewitness identification method). The research, carried out in
collaboration with Surrey Police, found that video line-ups are preferable
to sequential line-ups in producing accurate decisions, and that the use
of the matrix leads to no reliable change on accuracy rates (Wilcock &
Kneller, 2011), indicating appropriate use of Promat software.
References to the research
Hobbs, M. & Kneller, W. (2009). Effect of nitrogen narcosis on free
recall and recognition memory on open water. Undersea & Hyperbaric
Medicine, 36, 73-81.
Hobbs, M. & Kneller, W. (2011). Anxiety and Psychomotor Performance
in Divers on the Surface and Underwater at 40m (131ft). Aviation,
Space and Environmental Medicine, 82, 20-25.
Kneller, W., Higham, P., & Hobbs, M. (2012). Measuring manual
dexterity and anxiety in divers using a novel task at 35 - 41 m/115 - 135
ft. Aviation, Space and Environmental Medicine, 83, 54-57.
Kneller, W., & Hobbs, M. (2013). The levels of processing effect
under nitrogen narcosis.Undersea and Hyperbaric Medicine, 40,
Wilcock, R., & Kneller, W. (2011). A comparison of presentation
methods of video identification parades. Applied Cognitive Psychology,
Details of the impact
Kneller's work investigating cognitive performance in challenging
circumstances has had significant reach and importance in the two fields
in which they have been applied (diving and eyewitness testimony for
victims of crime). For research on diving, her findings are important in
terms of safety and practice of diving. Undersea divers have to cope with
numerous hazards and risks associated with marine high pressure
environments. One hazard is the occurrence of nitrogen narcosis, which is
experienced in deep sea dives. Narcosis causes significant cognitive and
psychomotor impairments in divers, and is a significant contributing
factor in diving-related accidents and impaired work-related performance.
However, the study of narcosis has historically been an under-researched
area and further studies are still required to establish the extent and
nature of cognitive impairments at specific water depths and how its
effects might be minimised. Understanding of the cognitive effects of
narcosis has implications for diver safety and performance in
recreational, commercial, and military diving.
Kneller's research on diving has also been particularly useful in
highlighting that the anxiety felt by divers in deep water may magnify
narcotic impairments underwater. At least four diving schools (West Bay
Diving School, Roatan, Honduras; Big Blue, Dahab, Egypt; Nautilus
Watersports, Port Vila, Vanuatu and Eastleigh Sub Aqua Club, Hants, UK)
throughout the world have considered this research when evaluating their
diving procedures. Additionally, it has also led to an improved manual
dexterity tool for testing divers which is smaller, more easily
transportable, cheaper and quicker to set up underwater than that
previously used (Purdue Pegboard or screw plate test). These are important
factors when considering the limited amount of time available to either
train or gather data from divers underwater. This new tool is now used by
the staff of West Bay Divers in Honduras when conducting deep diver
training with their customers (approx. 500 per year). In addition, the
research on the effects of narcosis on recall and recognition memory has
shown that narcosis-induced memory decrements cannot be explained simply
as an impairment of either encoding or retrieval strategies. Findings to
date have been published in specialist industry-specific journals (e.g. Undersea
& Hyperbaric Medicine) with the aim of disseminating the
knowledge to the diving community and researchers in this area.
For Kneller's work on eyewitness identification, there is direct impact
in policing practice. It has long been recognised that eyewitness
identification evidence can be highly fallible and is a major factor in
wrongful convictions in many countries (e.g. http://www.innocenceproject.org/).
In light of this, psychologists have been studying methods to increase the
accuracy of eyewitness identification performance for a number of years,
including methods by which a line-up can be presented. In England and
Wales, current police practice is to use identification parades on video
in a semi-sequential manner. After showing the line-up twice, police have
the option to show witnesses a screen with all nine line-up members at the
same time (the `matrix' format). The idea was that this format might
improve line-up identification rates. However, while this format has not
been formally assessed in this way, its use in another context (the
simultaneous line-up) has been shown to increase false identification
rates. Wilcock and Kneller (2011) found that the matrix had neither an
advantageous nor a detrimental effect on identification accuracy. This
work suggests that existing UK practice is appropriate (whether the matrix
is used or not); it also supports best practice for administering about
50,000 Promat line-ups that are run each year in the UK. In addition, the
work demonstrated that the UK video line-up procedure was superior to the
sequential line-up recommended by researchers in the USA. Publication of
this study led to Kneller being invited to present at a symposium for
practitioners in the field held by London South Bank University in
September 2012. The event was attended by 62 people, and a majority of
attendees were police officers and other criminal justice system
practitioners. In addition, the project has been referenced in a 2013
discussion article published in Policing (a leading policy and
practice publication) by Horry et al. regarding current practice of video
identification of suspects.
As a result of her knowledge and research in this area, Kneller has been
commissioned (along with other members of the South East Eyewitness
Network group led by Prof. Valentine) to produce a report for the British
Psychological Society regarding the current evidence-base to inform best
practice in obtaining identification evidence.
Sources to corroborate the impact
Cognitive effects of diving—
- Research reported in E-Slate (2009, 2011 & 2012), the on-line
journal of the American Academy of Underwater Sciences (AAUS). This is a
non-profit, self-regulating body dedicated to the establishment and
maintenance of standards of practice for scientific diving. It publishes
references to industry-relevant research. The references are: E-Slate
(2009), volume 3, issue 7, page 4; E-Slate (2011), volume 5, issue 2,
pages 5-6; and E-Slate (2012), volume 6, issue 3, page 6.
- Letter from West Bay Divers, Honduras confirming the impact of
Kneller's work on diving practice.
- Feedback report and list of attendees from of the Methods for
Eliciting Eyewitness Evidence symposium held by London South Bank
University, September 2012.
- Email correspondence from South East Eyewitness Network group
confirming involvement in British Psychological Society report.
- Letter from Prof. of Psychology, Goldsmiths University confirming
impact of Wilcock and Kneller (2011) study.
- Horry, R., Memon, A., Milne, R., Wright, D.B., & Dalton, G.
(2013). Video identification of suspects: A discussion of current
practice and policy in the United Kingdom, Policing (Advance
Access published March 12, 2013). doi: 10.1093/police/pat008.