Deffenbacher, K. A. (1980). Accuracy and confidence: Can we infer anything about their relationship? Law and Human Behavior, 4, 243-260.
Deffenbacher (1980) provides a review of many of the earlier studies conducted on the relationship between eyewitness confidence and accuracy. As can be seen, the relationship between confidence and accuracy is not a reliable one and a variety of methods have been used to conduct research ranging from finding either significant positive correlations or no correlation at all. In addition to providing somewhat of a review of research literature examining this important topic, Deffenbacher provides a theory regarding the disparity in results regarding findings of various correlations between confidence and accuracy with reliability coefficients of an unimpressive magnitude. He proposes an optimal processing hypothesis attempting to explain why certain studies find high positive correlations between confidence and accuracy and why others find near zero or negative correlations.
Under optimal conditions, the relationship between confidence and accuracy is thought to be high, yet under less than optimal conditions the relationship will decrease to chance levels or produce evidence of a negative relationship between the two variables. There is evidence to support the optimality hypothesis, with results indicating significant positive correlations based on methodologies in which the procedural phases of the experiment (i.e., encoding, retrieval) were carried out under conditions sufficient for optimal processing of information. Additionally, studies in which participants encoded and attempted to retrieve information regarding an event were conducted within low or poor processing conditions (i.e., noise, outdoors, low luminance) no significant positive correlations, and in some instances negative correlations, were found.
On the other hand, certain studies have found results which run counter to the proposals stemming from the optimality hypothesis. For example, certain studies using procedures conducive to optimal processing of information have found non-significant or negative correlations for the confidence and accuracy relationship. Thus, we researchers and those in the area of law enforcement need to be especially careful regarding attempts to predict accuracy from eyewitness confidence statements. Jurors may also be affected, because they are likely to be influenced by confidence statements (especially when high) made by witnesses, and infer accuracy from them (Wells, Lindsay, & Ferguson, 1979). It is important that all those using or examining confidence statements made by witnesses are extremely careful when interpreting or estimating how well they provide information relate to accuracy of a identification.
--By DJP
After reading Eyewitness Accuracy and Confidence by Kenneth Deffenbacher, I feel like I am somewhat more knowledgeable about the idea of accuracy and confidence and how they correlate with eyewitness identification. Personally, this article was one of the more difficult articles I have read so far. I believe it was hard to me to read because of the amount of different experiments and the different data and statistics the researchers were using. I couldn’t differentiate which study was which and which data went with certain studies. I will need to further review the article and possibly read the entire thing over again to fully understand the concept of the article.
For what I did get out of the article, seemed to prove that accuracy and confidence in the witnesses do matter in identifying suspects. One interesting topic the author brought up was how much of assertive and positive testimony had on the jurors seeing the witness as accurate and truthful. I believe the article stated that juror perceptions of witness confidence as accounted for 50% of the variance in juror judgments as to witness accuracy. The beginning of this article was very interesting to read all of the past research on this idea and how they are formulating new experiments on those past results.
Another interesting aspect of this article is when the Deffenbacher (1980) proposed all of the conditions that need to be tested when looking at accuracy and confidence in the witness. Warning of a memory test to come, situational stress, and opportunity to observe the target, familiarity of the target, retention intervals, additional information, and low similarity of the target to the foils are just some of the conditions listed. It is interesting that these small circumstances can have such a drastic effect on the ability of accurate identification.
This article was written in 1980, so it will be interesting to read more recent research and see if any of the questions in the article have been answered. I agree with Deffenbacher (1980) when he states that it is hard to define the exact criteria and level for distinguishing which factors effect accuracy and confidence more. More research and knowledge of this area in eyewitness identification is needed and will help educate others on this important need for our judicial system.
KC
I find the confidence/accuracy relationship to be a very intriguing line of research. More specifically, it is interesting because jurors tend to put so much confidence in this relationship, when it is somewhat questionable. The research concerning confidence and accuracy is very interesting, including the idea of choice acting as a moderator variable and the malleability of witness confidence.
Deffenbacher (1980) reports that another study has found that witness confidence accounts for about 50% of the variance of juror judgments. I find this number very amazing, and it makes me wonder why jurors rely on witness confidence so much. An eyewitness expert testifying helps jurors realize the weaknesses of this relationship, but I still wonder why jurors put so much emphasis on witness confidence. Is it because of a common sense notion that if a witness is confident, then they must be accurate in their decision? I think this idea might have something to do with jurors relying on witness confidence so much.
I also liked the article about choosing and witness confidence and accuracy. It was interesting to see that the relationship was higher for choosers as compared to non-choosers. Choosing seems to be a moderator variable of the confidence/accuracy relationship, and this finding is something that further research should focus on to fully understand. Maybe eyewitness confidence could be given further consideration if this relationship was explored further. I do like the recommendation that the authors make at the end of this article though. They believed that eyewitness experts should testify that witness confidence is only one of the many indicators of witness accuracy. I think this point should be stressed to jurors because it is important for them to not rely solely on witness confidence when making decisions that can affect a defendant’s life.
HC
Eyewitness Accuracy and Confidence by Kenneth Deffenbacher was somewhat confusing to me. This review looked at many assessments regarding the relationship of confidence and accuracy. However, with the high amount of research covered in this review, I feel as though I began to confuse ideas.
It was interesting to read that testimonies given in a clear, positive, confident, & assertive manor were treated by the courts as an accurate testimony whereas, less confident testimonies were accounted for as less accurate. This review suggested that not only did judges use witness confidence to indicate accuracy, but that jurors did this as well.
A study done by Wells, Lindsay, and Fergusons (1979) found that witness confidence accounts for approximately 50% of juror’s judgment variance. Reading this review lead me to believe that there is great debate on weather or not there is a clear relationship between witness confidence and accuracy of testimony.
I think that this topic should be researched more. I understand how people may think that a clear/confident response correlates to a more accurate testimony because it seem that the witness is being honest and knows that he/she is talking about. On the other hand, I am skeptical of this correlation knowing how the witness could be at acting/improv, or possibly that the witness has been trained well by the lawyer. It would be interesting to read about further/more recent research regarding this topic to see if the relationship between accuracy and confidence is clearer.
The Optimality Theory was somewhat confusing to me. However, I believe that it basically means the predictability of accuracy due to confidence varies greatly; it directly depends on the degree of optimality regarding information-processing conditions obtained during memory encoding, storage, etc.
I agreed with Deffenbacher when said that eyewitness experts need to educate judges & jurors when it comes to witness confidence
SD
I also agreed with Deffenbacher when he advocated for eyewitness experts to educate judges and jurors about witness confidence. It is important that jurors understand the relationship between witness confidence and accuracy because so much is potentially riding on a juror's decision. I would rather have a well educated jury making a decision than a jury that is unaware of the research issues surrounding a topic. This topic fits well with juror knowledge and the arguments about "common sense."