The Dangerous Unreliability of Eyewitnesses

Summary

The video script discusses the crucial role of eyewitness testimony in wrongful convictions and the scientific research behind improving identification accuracy. It highlights reforms in police procedures, such as warning witnesses that a suspect may not be present in lineups, and ensuring the administrator is unaware of the suspect. The script also critiques forensic techniques like fingerprint and bullet analysis, emphasizing the lack of scientific validation compared to DNA testing. The National Academy of Science urges a reevaluation of traditional forensic methods to ensure accuracy in criminal investigations.

Takeaways

• 🧠 Eyewitness testimony is the leading cause of wrongful convictions, despite extensive psychological research on its unreliability.
• 🔬 Over 30 years of research by experimental psychologists have explored how different techniques for photo arrays and lineups impact the accuracy of identifications.
• 📉 Simply warning a witness that the perpetrator may not be in a lineup can significantly reduce incorrect identifications without affecting accurate ones.
• 🔍 Double-blind procedures, where the administrator doesn't know the suspect, prevent bias and the influence of confirming feedback on witnesses.
• 📈 Confirming feedback, like praising a witness for their choice, can falsely increase their certainty and belief in their identification accuracy.
• ⚖️ Legal tests used to determine the reliability of witness identifications, such as certainty and attention, are misaligned with scientific evidence.
• 📚 A National Academy of Science report on forensic science stated that DNA testing is the only fully validated forensic method.
• 🧩 Pattern evidence such as fingerprints, tire tracks, and bullet striations lacks sufficient validation and statistical backing for reliability in court.
• ❌ Claims that a bullet or fingerprint uniquely matches a suspect’s gun or print to the exclusion of all others are scientifically unfounded.
• 🔄 The scientific community is urged to re-evaluate and research forensic pattern evidence to establish a more robust and reliable basis for use in court.

Q & A

What is considered the single greatest cause of wrongful convictions?

Eyewitness testimony is considered the single greatest cause of the conviction of innocent people.

What has experimental psychology research shown about eyewitness identification?

Research has shown that certain techniques, such as how photo arrays and lineups are conducted, can either improve the accuracy of identifications or lead to errors. The research highlights ways to enhance reliable identifications and reduce mistakes.

What is the significance of warning a witness that the perpetrator may or may not be in a lineup or photo array?

Giving this warning significantly reduces incorrect identifications without lowering the number of correct identifications. It helps prevent witnesses from guessing.

Why should the person administering a lineup or photo array be 'double-blinded'?

The administrator should not know who the suspect is to avoid influencing the witness, either intentionally or unintentionally. This prevents bias or feedback that could falsely inflate the witness’s certainty.

What is the effect of giving confirming feedback to a witness after identification?

Confirming feedback, such as telling a witness they made a correct identification, can falsely inflate their confidence in their choice and their belief that they had a good opportunity to observe the crime.

How does confirming feedback affect legal tests for eyewitness reliability?

Confirming feedback can distort factors like certainty, opportunity to observe, and attention, which are traditionally used by courts to evaluate eyewitness reliability, making these legal tests misaligned with scientific evidence.

What does the National Academy of Science report say about forensic sciences?

The report states that DNA testing is the only fully validated forensic discipline. Other pattern-based evidence, like fingerprints and bullet striations, lacks sufficient scientific validation.

What are the concerns with pattern-based forensic evidence like fingerprints and bullet striations?

Pattern-based evidence, such as fingerprints or bullet striations, often lacks a proper scientific foundation, including databases and statistical measures, to support claims of uniqueness or identification.

Why is DNA testing considered more reliable than other forensic disciplines?

DNA testing provides a statistical basis, offering frequency estimates for specific DNA profiles in different populations, unlike other forensic methods that often rely on subjective interpretations without statistical backing.

What did the National Academy of Science recommend for forensic disciplines besides DNA testing?

The Academy recommended that forensic disciplines like fingerprint analysis and bullet striation matching undergo more basic research to establish scientific validity and develop objective metrics for their findings.

Outlines

00:00

🔍 Eyewitness Testimony and Its Flaws

Eyewitness testimony is a leading cause of wrongful convictions. Research over the past 30 years has shown that certain techniques used in photo arrays and lineups are linked to more accurate identifications, while others lead to mistakes. For instance, warning witnesses that the real perpetrator might not be present significantly reduces incorrect identifications without affecting correct ones. Double-blind lineups, where the administrator doesn’t know who the suspect is, also reduce the influence of confirming feedback, which can artificially increase a witness’s confidence in their identification. Courts, however, still rely on outdated methods to assess the reliability of these identifications.

05:01

🔬 The Need for Scientific Validation in Forensic Evidence

The National Academy of Science has criticized the lack of scientific validation in many forensic disciplines, such as bullet and fingerprint analysis. Unlike DNA testing, which provides measurable statistical data, forensic experts have historically made exaggerated claims about the uniqueness of evidence like bullet striations or partial fingerprints. These claims lack a solid scientific foundation, as they do not account for the frequency of pattern similarities or offer statistical data. The report calls for more rigorous research to validate these methods and prevent the misuse of unreliable forensic techniques in court.

Keywords

💡Eyewitness testimony

Eyewitness testimony refers to the account given by people who have witnessed an event, particularly a crime. In the video, it is described as the single greatest cause of wrongful convictions, highlighting its potential unreliability. Despite its weight in legal cases, the video stresses the need for reforms in how such testimony is handled to avoid errors.

💡Photo array

A photo array is a lineup of photographs shown to a witness for the purpose of identifying a suspect. In the video, research demonstrates that how photo arrays are presented can greatly impact the accuracy of identifications. For example, telling a witness that the real perpetrator may or may not be present significantly reduces incorrect identifications.

💡Lineup

A lineup involves presenting several individuals to a witness to identify a suspect. Similar to the photo array, the way a lineup is conducted can lead to either accurate or mistaken identifications. The video mentions reforms, such as double-blind administration, to minimize bias and error during lineups.

💡Double-blind procedure

A double-blind procedure is when neither the witness nor the person administering a lineup or photo array knows who the suspect is. This reduces the chance of inadvertent suggestion or feedback. In the video, it is emphasized as a critical reform to ensure more reliable identifications in criminal investigations.

💡Confirming feedback

Confirming feedback refers to the practice of affirming a witness's choice during identification, such as saying 'good choice.' The video highlights that this can artificially increase the witness's confidence, making them more certain about their identification, even if it's incorrect. This phenomenon distorts the reliability of eyewitness testimony.

💡Meta-analysis

Meta-analysis is a statistical method that combines results from multiple studies to derive conclusions with a high level of confidence. The video refers to meta-analyses that have been conducted on eyewitness identification techniques, showing which methods are more reliable and which tend to lead to errors.

💡Pattern evidence

Pattern evidence involves the analysis of patterns, such as fingerprints, tire tracks, or striations on bullets, to link a suspect to a crime. The video questions the scientific validity of such evidence, noting that, unlike DNA testing, there is often no solid database or statistical basis for such claims.

💡Striations on bullets

Striations are the microscopic marks left on a bullet as it is fired from a gun, which can theoretically be matched to a specific firearm. In the video, this type of forensic evidence is criticized for lacking scientific rigor, as experts often claim to match bullets to guns without any clear statistical basis for their certainty.

💡Forensic science

Forensic science involves the use of scientific methods and techniques to investigate crimes. The video discusses a report by the National Academy of Science that criticizes many forensic disciplines, arguing that only DNA testing has been properly validated, while other methods, like pattern evidence, are not as scientifically sound.

💡DNA testing

DNA testing is a scientifically validated method used in forensic science to identify individuals based on their genetic material. The video points out that DNA testing stands out as the only forensic method that provides statistically supported conclusions, contrasting it with less reliable methods like fingerprint or bullet analysis.

Highlights

Eyewitness testimony is the single greatest cause of wrongful convictions.

Over 30 years of research by experimental psychologists have improved our understanding of what makes identifications accurate or prone to error.

Telling a witness that the perpetrator may or may not be in the lineup significantly reduces false identifications.

This warning reduces incorrect identifications without significantly affecting correct ones.

Double-blind administration of lineups, where the administrator does not know the suspect, helps prevent bias.

Feedback like 'good job' after a witness selects someone from a lineup can falsely inflate their confidence in their identification.

The legal system often uses factors like certainty and opportunity to observe to assess the reliability of eyewitness testimony, which research shows can be unreliable.

Scientific studies show that suggestive procedures can artificially inflate witness confidence in their identification.

The National Academy of Science issued a landmark report criticizing the lack of scientific validation in many forensic sciences.

DNA testing is the only forensic discipline with established scientific validation.

Pattern evidence disciplines, such as fingerprint and ballistic analysis, lack proper scientific validation according to the National Academy of Science.

Experts often claim that bullets or fingerprints 'uniquely' match a suspect’s weapon or prints, but this lacks statistical backing.

Forensic analysts often provide conclusions like 'to the exclusion of all other guns in the universe,' which are not scientifically defensible.

There is a lack of databases and statistical analysis in forensic disciplines like ballistic matching and fingerprint analysis.

Even with fingerprints, partial prints at crime scenes make it difficult to scientifically claim a unique match to an individual.

Transcripts

eyewitness testimony uh of course is the

single greatest cause of the conviction

of the innocent and what's fascinating

about that is that U we have now um 30

years more than 30 years of fantastic

research from experimental psychologists

who have uh you know recreated crime

scene recreated uh events and uh played

around with which different

way we do a photo array or a lineup and

different techniques that are used

correlate more with accurate and

reliable identifications and which uh

techniques lead to errors and uh a

number of reforms have been uh uh uh

adopted uh by federal uh commissions and

uh American Bar Association the

International Association of chiefs of

police lots of policing entities based

on really good scientific research

I mean a lot of This research there's

meta analyses uh that's where you pull

together lots of different studies um

and you have a lot of confidence that

certain things uh uh are real effects

and I'll give you some examples uh that

may surprise people um for example

before you show somebody a photo array

or a live lineup you should tell the

witness um we're now going to show you

some pictures or people uh please keep

in in mind that the real perpetrator may

or may not be in this photo array or

lineup and if you don't make an

identification don't worry the

investigation will continue just giving

that warning uh dramatically reduces

incorrect

identifications Without Really reducing

correct identifications and that's of

extraordinary importance obviously in

terms of being able to go out find the

real perpetrator and not arrest the

wrong person uh there's lots of reasons

we think that this warning will reduce

eror uh certainly it inhibits people

from guessing and uh uh there's kind of

a natural inclination to do that um

another reform that's of really critical

importance is that the person that

administers the lineup of the photo

array should be double blinded that is

to say that the person should not know

who uh the suspect

is um uh and that's important for many

reasons uh not the least of which is the

possibility of

uh

feedback um confirming feedback what

again meta analyses have shown is that

if you uh say to somebody ah you pick

that number to good or give some kind of

confirming feedback whether you're a law

enforcement person or somebody else

frankly what this does is it can falsely

infl plate the person's certainty that

they made the correct identification the

witness's belief that they had a good

opportunity to observe the witness's

belief that they were paying

attention when the crime was committed

um all of these factors by the way

certainty opportunity to observe paying

attention are all factors that the

courts used to be using or use frankly

in trying to weigh the reli ability of

identification when we know that let's

say some suggestive procedure has been

used so posi uh uh confirming feedback

or even just the use of an unduly

suggested procedure can falsely inflate

these so-called reliability factors uh

uh certainty opportunity to observe

attention paid and uh the legal tests

are out of whack um with what the

scientific evidence

shows more than a year ago now the

National Academy of Science came out

with a report about forensic science

generally extremely important report a

landmark report that anybody really

interested in this field should look at

um and this report uh basically said

look DNA testing is the only validated

uh forensic discipline we have um and in

particular when you look at pattern

evidence and by this they were talking

about fingerprints and tire tracks and

looking at cations on bullets and trying

to deter excuse me whether they came

from a gun particular gun or not um all

these pattern

disciplines had not been adequately

validated uh because you would have uh

uh uh experts coming into court and they

say I'm looking at the striations of

this bullet that we recovered from the

crime scene and now I found this

defendant's gun and I fired a bullet

from that and I'm looking at the two of

them under a microscope and I see all

these lines and I think there's quote

unquote sufficient agreement and by that

and if I'm really a big quality

assurance lab I'll bring my buddy in and

he'll look at the microscope and he'll

say I think there's also agreement here

and from this I can now tell you that

this bullet came from that gun to the

exclusion of all other guns in the

universe well think about it

scientifically on what basis do you have

a database can you tell us anything

about the frequency of finding similar

patterns if indeed you have similar

patterns do you have measurement area

here can you give us a number you know

with DNA testing we can give you a

number we can give you the frequency of

a particular DNA profile in uh various

different populations can you give us a

statistic um and the answer is no they

weren't giving statistics as a matter of

fact they were just saying it's Unique

this bullet comes from that gun to the

exclusion of all guns in the universe

this is nonsense and the National

Academy of Science said so and say you

guys have really got to go back to the

drawing board and do some basic research

uh to find out what the answers are to

that question even

fingerprints um which we know when if

you take all 10 uh prints and you scan

it in and you put it into a data the

database of known uh fingerprints you

can do a pretty good job of identifying

somebody but that's not the question

when you're talking about a small latent

print at a crime scene you get a partial

thumb print let's say and every time you

lay down a print it's always a little

bit uneven and then you compare it to

somebody else's thumb print can you say

that this small latent uniquely comes

from that individual well uh that is the

way the testimony was going in for years

and it was uh uh uh without scientific

basis to say that it uniquely was this

person's print you can't say that