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THE VIRTUAL LICENCE PLATE (VLP) AND ITS EFFECT ON EYEWITNESS

PERFORMANCE

An update on ongoing research

David Emmett, Brian R. Clifford, Kelly Young, Margarita Kandova, & Anita Potton

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The problem“Eyewitness recall of a licence plate can be the backbone for case solutions.”

MacKinnon, O’Reilly & Geiselman (1990)

“In events such as hit and run accidents the time available for viewing the licence plate is often between 0.2 and 5 seconds.”

Al-Haboubi (1999)

“Witness reports are often incomplete distorted or inaccurate.”

Fisher & Geiselman (1992)

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The potential

With licence plate details now computerised in most countries, vehicle owner searches can be carried

out with great speed even on partial details.

Clearly, however, the more licence plate characters that a witness correctly recalls then the greater is

the chance that a vehicle owner can be successfully traced.

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Previous research

Despite the potential importance of licence plate recall to criminal investigations, a

search of the extant eyewitness literature prior to the commencement of this series of studies, reveals almost a complete lack of

research into either the ability of eyewitnesses to accurately recall the details

of vehicle licence plates or ways in which such recall can be assisted

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MacKinnon, O’Reilly & Geiselman (1990)

In a study using a series of still slides as stimuli in which a 7 character Californian licence plate was visible from various distances and with varying

clarity for a total of 45 seconds

together with immediate recall.

A control group correctly recalled 3.15 characters.

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A second group, using a simulated licence plate made from coloured cardboard with removable vinyl alphanumeric characters, achieved a non significant 7% increase in

characters recalled.

A third group, using the plate simulator and the context reinstatement mnemonics of the cognitive interview, achieved a significant increase of 22% in correct character recall

MacKinnon, O’Reilly & Geiselman (1990)

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The current series of studies

A 21st century approach

The Virtual Licence Plate (VLP)

An electronic version of MacKinnon, O’Reilly & Geiselman’s cardboard

simulator

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Brief history of this researchEarly studies in this series concentrated on testing

the efficacy of the concept of using a Virtual Licence Plate as a memory retrieval aid and then developing

the VLP to its maximum efficiency.

Significant improvement in eyewitness recall of licence plates was seen using the VLP, especially in

conjunction with Mental Context Reinstatement.

The results of two early studies using VLP v.1 and v.2 were reported in

Emmett, D., Clifford, B. R., Young, K., & Potton, A. (2004).

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Present state of the research

During the initial studies it was clear that the use of the VLP in conjunction with MCR was

having a beneficial effect on the recall of details of the crime scene beyond the licence

plate

Testing needed to be carried out using both the ‘old’ and ‘new’ style UK licence plates.

Would similar results be seen?

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The current studies

Two studies are presented

Both use VLP v.2 and MCR

Recall of licence plate and general crime scene details tested

Old and new style UK licence plates

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A brief introduction to VLP v.2

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VLP v.2

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‘New’ and ‘Old’ style plates

‘OLD’

‘NEW’

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Experiment 1

Stimulus

Video of staged child abduction with ‘old style’ licence plate clearly visible for 3 seconds

watched as individuals

Participants

104 undergraduates – naïve as to reason for watching video

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Experiment 1Delay

5 minutes – filled with Ravens Matrices to prevent rehearsal

Recall

4 conditions – each conducted individually

Control – pencil and paper recall

VLP only – experimenter operated use of VLP

MCR only – individual MCR instructions

VLP + MCR – above two conditions in combination

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Dependent Variables

Alphanumeric licence plate character correctly recall in the correct location

Correctly recalled details of the crime scene, other than the licence plate, through cued

recall

Errors are not being included in this presentation

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Licence plate characters

groupCharacters correctly recalled

Significance compared to

control

control 3.35

VLP 4.12 p > 0.05

MCR 4.62 p < 0.05

VLP + MCR

5.65 p < 0.001

0 – 4 characters correctly recalled

5 -7 characters correctly recalled

Control 57.7% 42.3%

VLP 53.8% 46.2%

MCR 50.0% 50.0%

VLP + MCR 11.5% 88.5%

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Recall of crime scene details

group

Items of information

correctly recalled

Significance compared to

control

control 25.08

VLP 25.92 p > 0.05

MCR 31.92 p < 0.05

VLP + MCR 37.65 p < 0.001

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Experiment 2

StimulusVideo of staged street arrest with ‘new style’

licence plate clearly visible for 5 seconds

watched as individuals

Participants48 undergraduates – naïve as to reason for

watching video

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Delay5 minutes – filled with Ravens Matrices to prevent

rehearsalRecall

3 conditions – each conducted individuallyControl – pencil and paper recall

MCR only – individual MCR instructionsVLP + MCR – above two conditions in

combinationDependent Variables - as before

Experiment 2

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Licence plate characters

groupCharacters correctly recalled

Significance compared to control

control 2.81

MCR 4.94 p < 0.01

VLP + MCR

6.31 p < 0.001

0 – 4 characters correctly recalled

5 -7 characters correctly recalled

Control 87.5% 12.5%

MCR 31.3% 68.7%

VLP + MCR 12.5% 87.5%

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Recall of crime scene details

group

Items of information

correctly recalled

Significance compared to

control

control 23.38

MCR 29.06 p < 0.05

VLP + MCR 35.63 p < 0.001

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Discussionlicence plate details

Clearly in both experiments the use of the VLP and particularly the use of the VLP in combination with MCR has led to a marked increase in licence plate

recall.

In the case of the VLP plus MCR combination this increase was significant in both experiments

Experiment 1- increase of 2.30 characters

Experiment 2 - increase of 3.50 characters

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Mental Context Reinstatement

Based upon the MCR mnemonic of the Cognitive Interview

Witness mentally reinstates the context of the to-be-remembered event.

Technique applied with great care and intensity.

Encoding Specificity Hypothesis/Principle(Tulving, 1976; 1983; Tulving & Thompson, 1973)

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Increase in contextual cues that enable the witness to bring to life their encoded memory trace. This is

particularly true of the characters that the witness adds to the plate. Each character acting as a powerful

cue to the next.

Encouragement of witness to concentrate and consider different ‘candidate combinations’ of

characters.

VLP v.2

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Part recognition task – Initial retrieval is a recall task but then VLP provides a solid manifestation of that recall enabling the witness to compare it directly

with the encoded trace in a recognition-like process.

Allows witness to access the power of the ‘change order’ mnemonic of the CI.

VLP v.2

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Clear that there is an additive if not multiplicative effect when using VLP with MCR

MCR requires witnesses to focus on the target licence plate and form a mental image of it. The VLP enables the witness to bring that mental image into

concrete existence, to examine it, and through a process of comparison with the encoded trace refine

it until as close a match as possible is achieved.

+ MCR

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Clearly in both experiments the use of the VLP in combination with MCR has led to a marked

increase in the recall of crime scene details other than the licence plate

.This increase was significant in both experiments

Experiment 1- increase of 50.1%

Experiment 2 - increase of 52.4%

Recall of crime scene details

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Mental Context Reinstatement

The strongest effects are typically found in free recall, with less strong effects in cued recall

Technique applied with great care and intensity.

Increases with MCR alone

Experiment 1- increase of 27.3%

Experiment 2 - increase of 24.3%

VLP v.2 Makes little apparent contribution on its own

Experiment 1- increase of 3.3%

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+ MCR

Clearly, as with the licence plate details there is an additive if not multiplicative effect on general crime scene recall when using VLP with MCR

How does a technique designed to improve recall of licence plates also exerts a highly beneficial effect on the

recall of details of the event of which the licence plate forms a part?

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The witnesses’ mind is focussed sharply onto both the licence plate and the events

that surround it.

Increased interaction between witness and experimenter leads to increased feelings of

involvement and motivation

+ MCR

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Next stepsCombining MCR with the VLP not only offers

investigators a powerful practical tool to assist eyewitnesses in the recall a target licence plate

but also details of the event within which the licence plate is embedded.

We now feel that the time is right to move out of the lab and into live trials with the Police service

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Last question

What was the licence plate that you saw at the beginning?