Keeping innocent people out of jail using the science of perception
Scientists devise a new lineup method to help eyewitnesses more
accurately identify suspects

Date:
July 14, 2020
Source:
Salk Institute
Summary:
People wrongfully accused of a crime often wait years -- if ever --
to be exonerated. Many of these wrongfully accused cases stem from
unreliable eyewitness testimony. Now, scientists have identified a
new way of presenting a lineup to an eyewitness that could improve
the likelihood that the correct suspect is identified and reduce
the number of innocent people sentenced to jail.



FULL STORY ========================================================================== People wrongfully accused of a crime often wait years -- if ever --
to be exonerated. Many of these wrongfully accused cases stem from
unreliable eyewitness testimony. Now, Salk scientists have identified
a new way of presenting a lineup to an eyewitness that could improve
the likelihood that the correct suspect is identified and reduce the
number of innocent people sentenced to jail. Their report is published
in Nature Communications on July 14, 2020.


========================================================================== "Misidentification by eyewitnesses is a long-standing problem in our
society.

Our new lineup method uncovers the structure of eyewitness memory, removes decision bias from the identification process, and quantifies performance
of individual witnesses," says Salk Professor Thomas D. Albright, co-corresponding author of the study. "This study is a great example
of using laboratory science to bring about criminal justice reform."
In the United States, nearly 70 percent of DNA exonerations are due
to misidentifications by eyewitnesses, according to the Innocence
Project. To overcome this societal problem, research has focused on
factors that influence the likelihood that a witness will identify the
correct person. One key factor is the way individuals are presented to
the eyewitness during the lineup, according to Albright, who co-chaired
a National Academy of Sciences committee to examine the validity of
eyewitness identification. Albright, an expert in the fields of visual perception and recognition, taps into decades of research suggesting
that people commonly misperceive visual events, and memories of those
events are continuously augmented and deteriorate over time.

Currently, the two most common (or traditional) methods used by law
enforcement are known as simultaneous and sequential lineups. In the simultaneous method the eyewitness views six photographs of individuals at
the same time; in the sequential method the eyewitness views six photos,
one at a time. The witness then either identifies a suspect or rejects
the lineup if no face matches their memory of the crime scene.

The research team sought to create a new lineup method that would help
estimate the strengths of memories for each face and eliminate unconscious biases that shape decisions without awareness.

"Traditional lineups just reveal the top choice -- the tip of the
iceberg. But the cause of the witness's decision is ambiguous. It may
reflect strong memory for the culprit, or it may mean that the witness
was not very discerning," says Albright. "Our new procedure overcomes
that ambiguity by revealing the strength of recognition memory for all
lineup faces." The scientists used a technique, called the method of
paired comparisons, which works similar to how an optometrist gives an
eye exam: Just like looking through pairs of lenses and stating which
lens is clearer, the eyewitness is shown two photographs of individuals
at a time and they choose the one that looks more similar to the person
they remember from the crime scene. The procedure yields an estimate of
the strength of recognition memory for each lineup face. Statistical
analysis of these memory strengths then reveals the probability of
correctly identifying the culprit.

"Our methods derive from a branch of science called sensory
psychophysics," says Staff Scientist Sergei Gepshtein, first and co-corresponding author of the paper, who founded and directs the
Collaboratory for Adaptive Sensory Technologies at Salk. "Psychophysical
tools are designed to reveal how properties of the physical world are
ordered -- or 'scaled' -- in the mind. Our approach allowed us to peek
into the 'black box' and measure how lineup faces are organized in the witness's memory in terms of their similarity to the culprit." The paired comparison method yields greater information about the identity of the
culprit than previous methods. What is more, it offers an unprecedented quantitative index of certainty for individual eyewitnesses, which is
what the judge and jury really need to know.

"The conduct of a lineup is just one application of our method," says Gepshtein. "Another application is selection of lineup 'fillers,'
which are faces of people known to be innocent. The fillers should
not be too similar or too dissimilar to the suspect. Because the new
method reveals the perceived similarity of faces, it can be used to
optimize the choice of lineup fillers." The paired comparison lineup
holds much promise as a research tool as well as a practical tool for investigation and prosecution of crimes. The authors hope that the new technique will soon be applied in real police casework, leading to more
correct identifications and fewer wrongful convictions.

"Convictions should be based on science, not precedent," says Albright.


========================================================================== Story Source: Materials provided by Salk_Institute. Note: Content may
be edited for style and length.


========================================================================== Journal Reference:
1. Sergei Gepshtein, Yurong Wang, Fangchao He, Dinh Diep, Thomas D.

Albright. A perceptual scaling approach to eyewitness
identification.

Nature Communications, 2020; 11 (1) DOI: 10.1038/s41467-020-17194-5 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200714123347.htm

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