Social recognition memory: the effect of other people's responses for previously seen and unseen items

When people discuss their memories, what one person says can influence what another person reports. In 3 studies, participants were shown sets of stimuli and then given recognition memory tests to measure the effect of one person's response on another's. The 1st study (n = 24) used word recognition with participant-confederate pairs and found that the effect of confederate responses on participant responses was larger for previously unseen items than for previously seen items (omega(p) = .23). This finding was replicated in the 2nd study, which used photographs of cars (n = 24). In the 3rd study (n = 54), which used photographs of faces with participant pairs, the effect was also larger for unseen items. Results indicate that people rely more on other people's memories for unremembered objects than for remembered objects. This is important for both theories of memory and applications (e.g., witnesses talking, students studying together).     

The co-witness misinformation effect: memory blends or memory compliance?

For 30 years hundreds of researchers have shown participants videos and slide-sequences of events, presented the participants with misleading information, and found that this misinformation distorted their memories. The purpose of this study was to establish whether those misled participants are reporting a memory blend of the two sources of information or whether they are simply complying with the post-event information. A total of 92 participants were shown one of two versions of six different videos, which included some subtle differences. After having watched each video individually, participants were paired with someone who had seen the other version and they discussed the clips together. They then individually answered questions about the videos, and their responses showed that some of the distorted memories were blends of the original information and the post-event information. The implications of these findings are discussed.     

Postidentification feedback affects real eyewitnesses

Many studies of simulated eyewitness situations have shown that under certain laboratory conditions, people's confidence about their identifications predicts their accuracy, but that their reported confidence can be affected by telling them that they chose the suspect. In this study, eyewitnesses (n= 134) to real crimes took part in lineups at an identification suite in the United Kingdom and were asked questions about their memory both before and after they were told whether they had identified the suspect or a filler. Before the eyewitnesses were told whether they had identified the suspect or a filler, their responses to several questions reliably differentiated between those who identified the suspect and those who identified a filler. In addition, responses to the memory questions were affected by telling the eyewitnesses whether or not they had identified the suspect. These results show that postidentification feedback affects real eyewitnesses and highlight the importance of recording meta-memory variables before an eyewitness discovers whether he or she has identified the suspect.     

Forecasting “friends forever”: A longitudinal investigation of sustained closeness between best friends

Using data collected across 19 years, the chief goal of this study was to discover predictors of continued relational closeness between best friends. Participants were same‐sex and cross‐sex best friend pairs recruited from a small Midwestern college. In 1983, participants completed several tests and activities designed to assess facets of intimacy, with follow‐up studies in 1987 and 2002 measuring relational closeness. Regression analysis indicates that both manifest similarity and months of closeness in 1983 are associated with relational closeness in 2002. These results suggest that the investment of resources in the friendship and similarity between friends facilitate friendship longevity and that Kelley et al.’s (1983) conceptualization of closeness as related to interdependence is empirically robust.     

Co‐witness feedback in line‐ups

The aim of the current study was to establish whether feedback from a co‐witness concerning their choice of suspect could influence an individual witness' certainty and other testimony‐relevant judgements. Eighty‐two university students and members of the general public viewed a film of a staged mugging in pairs and then made an identification of who they thought was the suspect from a culprit‐absent line‐up (i.e. identification parade). The participants were then required to tell their partner whom they had identified and to fill out a questionnaire with testimony‐relevant questions (e.g. How good a view did you get of the person in the line‐up?). When the pairs of participants agreed on their choice of suspect, their scores on the testimony‐relevant questions tended to be higher than when the pairs did not agree. This shows that co‐witnesses can influence each others' memory reports when giving each other feedback after the identification process. The implications of these findings are discussed. Copyright © 2006 John Wiley & Sons, Ltd.     

Susceptibility to postidentification feedback is affected by source credibility

How much a person is affected by postidentification feedback is dependent on the credibility of the person giving the feedback. Seven hundred and ninety participants across three experiments viewed a crime video, made judgments from a line‐up, were provided with co‐witness and/or outcome feedback (from police officers [high credibility] or children [low credibility]), and answered testimony‐relevant questions (e.g. How good a view did you get of the person in the video?). The aim was to find out how high versus low credibility co‐witness feedback affects a witness' retrospective judgments (Experiment 1) as well as estimations of these co‐witnesses' judgments (Experiment 2). Experiment 1 showed that the feedback effect was only observed when the co‐witness responses were attributed to a high credibility source. Experiment 2 showed that high credibility co‐witnesses were estimated to score higher on the testimony‐relevant questions as compared to low credibility co‐witnesses. Experiment 3 showed that outcome feedback (e.g. ‘you identified the suspect’) produces stronger effects on testimony‐relevant questions than co‐witness feedback. The implications of these findings are that when postidentification feedback is present, it is important to determine the source of this feedback. Copyright © 2008 John Wiley & Sons, Ltd.     

When Eyewitnesses Talk

ABSTRACT— When two people witness an event, they often discuss it. Because memory is not perfect, sometimes this discussion includes errors. One person's errors can become part of another person's account, and this proliferation of error can lead to miscarriages of justice. In this article, we describe the social and cognitive processes involved. Research shows how people combine information about their own memory with other people's memories based on factors such as confidence, perceived expertise, and the social cost of disagreeing with other people. We describe the implications of this research for eyewitness testimony.     

Functions for traditional and multilevel approaches to signal detection theory

In the present article, functions written in the freeware R are presented that calculate several measures from traditional signal detection theory for each individual in a sample, along with summary statistics for the sample. Bias-corrected and accelerated bootstrap confidence intervals are also produced. Arguments are made for using an alternative approach—multilevel generalized linear models—and a function is presented for it. These functions are part of the R package sdtalt, which is available on the Comprehensive R Archive Network. Recent data from memory recognition studies are used to illustrate these functions.     

The co-witness misinformation effect: Memory blends or memory compliance?

For 30 years hundreds of researchers have shown participants videos and slide-sequences of events, presented the participants with misleading information, and found that this misinformation distorted their memories. The purpose of this study was to establish whether those misled participants are reporting a memory blend of the two sources of information or whether they are simply complying with the post-event information. A total of 92 participants were shown one of two versions of six different videos, which included some subtle differences. After having watched each video individually, participants were paired with someone who had seen the other version and they discussed the clips together. They then individually answered questions about the videos, and their responses showed that some of the distorted memories were blends of the original information and the post-event information. The implications of these findings are discussed.     

Examining mixed unknown distributions (mud)

A function, written in R, for testing whether the distribution of responses in one condition can be considered a combination of the distributions from two other conditions is described. The important aspect of this function is that it does not make any assumptions about the shape of the distributions. It is based o nthe Kolmogorov-Smirnov D statistic. The function also allows the user to test more specific and, hence, more statistically powerful hypotheses. One hypothesis, that the mixture does not capture the middle third of the distribution, is included as a built-in option, and code is provided so that other alternatives can easily be run. A power analysis reveals that the function is most likely to detect a difference between the combined conditions' distribution and the other distribution when the center of the other distribution is near the midpoint of the two original distributions. Critical p values are estimated for each set of distributions, using bootstrap methods. An example from human memory research, exploring the blending hypothesis of the misinformation effect, is used for illustrative purposes.