Earwitness memory: distortions for voice pitch and speaking rate

In two experiments, memory distortions for voice pitch and speaking rate were examined. In both experiments, a significant distortion effect for voice pitch was observed, with listeners biased towards selecting voices lower in pitch than low‐pitch targets and selecting voices higher in pitch than high‐pitch targets. In contrast, for speaking rate there was little evidence for the production of memory distortions. The results are discussed in terms of transient surface properties of speech and how transience may be a factor in producing distortions. The results have implications for how errors arise during earwitness testimony for a suspect's voice. Copyright © 2009 John Wiley & Sons, Ltd.     

Earwitnesses: effects of accent,retention and telephone

An experiment was conducted to investigate the effects of accent, telephone and a relatively long retention interval (3 or 8 weeks) on speaker identification. Three‐hundred and sixty participants heard the target's voice and were asked to identify the target by means of a line‐up consisting of 6 voices. Half of the participants were given a target‐present line‐up and the other half a target‐absent line‐up. The results showed that 24% of participants correctly identified the target in the target‐present condition (hits), whereas 50% of participants incorrectly identified a person as the target in the target‐absent condition (false alarms). The speaker with the standard‐accented voice was more often correctly recognized than the speaker with the non‐standard‐accented voice. No difference was found between identification accuracy after one, three or eight weeks and between the telephone and non‐telephone conditions. It can be concluded that there is a relatively high probability that an innocent defendant is identified as the perpetrator, even in a procedurally correct voice line‐up (in this experiment 8%). Furthermore, reliability may be drastically reduced when the perpetrator has a strong accent, unfamiliar to the listener. On the other hand, reliability of a voice line‐up seems not to be affected by a presentation over the telephone, as well as by a retention interval of at least 8 weeks. Copyright © 2006 John Wiley & Sons, Ltd.     

A meta‐analysis of the effects of acute alcohol intoxication on witness recall

There is widespread belief in the legal system that alcohol impairs witness testimony. Nevertheless, most laboratory studies examining the effects of alcohol on witness testimony suggest that alcohol may affect the number of correct but not incorrect details recalled. However, it is difficult to draw conclusions because sample sizes, testing paradigms, and recall measures vary between individual studies. We conducted a meta‐analysis to address this issue. We found alcohol intoxication had a significant and moderate sized effect on the number of correct details recalled (g = 0.40). The effect of alcohol on the number of incorrect details recalled was not significant. Further, the effect of alcohol on the recall of correct details was significantly moderated by multiple factors like intoxication level, the retention interval length between encoding and recall, and the types of questions asked (i.e., free recall vs. cued recall). We discuss the applied implications of the results.     

Mechanism underlying the self-enhancement effect of voice attractiveness evaluation: self-positivity bias and familiarity effect

The aim of the present study was to determine whether the self-enhancement effect of voice attractiveness evaluation is due to general self-positivity bias and/or the familiarity effect. The participants were asked to rate the attractiveness of their own voice, a friend's voice and strangers' voices. In addition, a self-reference valence (SR-valence) task was adopted in the experiment. Significant self-enhancement effects in voice attractiveness ratings were demonstrated, regardless of whether the participants recognized their self-voice or not. However, the friend-enhancement effect was found in only those participants who successfully recognized their friend's voice. Moreover, a significant correlation was found between self-positivity bias in the SR-valence task and the self-enhancement effect (but not the friend-enhancement effect). Our findings suggest that both the familiarity effect and self-positivity bias account for the vocal self-enhancement effect, and the influence of self-positivity bias could be implicit. The present study thus provides empirical evidence to clarify the potential explanations for the self-enhancement of voice attractiveness assessment.     

Earwitnesses: effects of speech duration,retention interval and acoustic environment

An experiment was conducted to investigate the reliability of voice lineups. More specifically, the experiment was designed to look into the effects of retention interval (an immediate test or after a week), speech duration (30 or 70 s) and acoustic environment (indoors or indoors and outdoors) on speaker identification accuracy. In addition, the relation between confidence assessments of both participants and test assistant on the one hand and identification accuracy was explored. A total of 361 participants heard the target voice in one of four exposure conditions (short or long text and speech samples recorded only indoors or indoors and outdoors). Half the participants were tested immediately after exposure to the target voice and half 1 week later. The results show that the target was correctly identified in 42% of cases. In the target‐absent condition there were 51% false alarms. Acoustic environment did not affect identification accuracy. There was an interaction between speech duration and retention interval in the target‐absent condition. When listeners were tested after a week, they made fewer false identifications if the speech sample was long. No effects were found when participants were tested immediately. Only the confidence scores of the test assistant had predictive value. Taking the confidence score of the test assistant into account therefore increases the diagnostic value of the identity parade. Copyright © 2004 John Wiley & Sons, Ltd.     

Control of voice gender in pre‐pubertal children

Adult listeners are capable of identifying the gender of speakers as young as 4 years old from their voice. In the absence of a clear anatomical dimorphism in the dimensions of pre‐pubertal boys' and girls' vocal apparatus, the observed gender differences may reflect children's regulation of their vocal behaviour. A detailed acoustic analysis was conducted of the utterances of 34 6‐ to 9‐year‐old children, in their normal voices and also when asked explicitly to speak like a boy or a girl. Results showed statistically significant shifts in fundamental and formant frequency values towards those expected from the sex dimorphism in adult voices. Directions for future research on the role of vocal behaviours in pre‐pubertal children's expression of gender are considered.     

Co‐Witness Confidence,Conformity, and Eyewitness Memory: An Examination of Normative and Informational Social Influences

We explored conformity and co‐witness confidence in eyewitness memory. Confederates provided misleading information and confidence ratings during a cued recall test, and participants publicly provided answers to this test in turn. Participants performed memory tests with a confederate, then completed individual memory tests. Results indicated that confederates who answered questions prior to participants impacted their public and private memory reports for accurate information but only impacted public reports for misleading information. Participants' confidence in their performance in the presence of a confederate mirrored the confederate's confidence levels, suggesting a confidence conformity effect. Results are explained in terms of differential effects of informational and normative influence for accuracy and confidence in co‐witness memory reports. Copyright © 2012 John Wiley & Sons, Ltd.     

The Letter and the Witness: Agamben,Heidegger, and Derrida

In Remnants of Auschwitz, Agamben introduces a particular conception of bearing witness to overcome the problems contained in an account of language that depends on the voice or the letter. From his earlier work, it is clear that his critique of the voice and the letter is not only directed to ancient and medieval metaphysics, but also concerns Heidegger's account of the voice and Derrida's account of the letter and writing. Yet, if Agamben is correct in claiming that bearing witness offers an alternative to Heidegger's voice and Derrida's letter, it is remarkable – a fact unnoticed in the available literature – that Agamben does not discuss how these conceptions of the voice and the letter are intrinsically connected to the problem of testimony for Heidegger as well as Derrida. To show how this lack of attention to bearing witness in Heidegger and Derrida affects Agamben's critique, this article proceeds as follows. First, we interpret Agamben's critique of Heidegger's conception of the voice and Derrida's conception of writing in terms of the presuppositional constitution of metaphysics. Second, we describe Agamben's concept of the witness and indicate how it offers an alternative to this presuppositional constitution of metaphysics. Finally, we show which role bearing witness plays in Heidegger's voice and Derrida's letter, and how our analysis presents a more precise version of Agamben's critique.     

The “other-accent” effect in voice recognition

The current paper examines an “other-accent” effect when recognising voices. English and Scottish listeners were tested with English and Scottish voices using a sequential lineup method. The results suggested greater accuracy for own-accent voices than for other-accent voices under both target-present and target-absent conditions. Moreover, self-rated confidence in response to target-absent lineups suggested greater confidence for own-accent voices than other-accent voices. As predicted, the other-accent effect noted here emerged more strongly for English listeners than for Scottish listeners, and these results are discussed within an expertise framework alongside both other-race effects in face recognition, and other-accent effects in word recognition. Given these results, caution is advised in the treatment of earwitness evidence when recognising a voice of another accent.     

Witness Vetting: What Determines Detectives' Perceptions of Witness Credibility?

During the course of a criminal investigation witness vetting, a detective's process of determining the credibility and weight of witness information, can lead to errors in an investigation that can go virtually unchallenged. Witness confidence, opportunity to view, and type of information proffered were examined in relation to detective inferences about witness reliability, accuracy, and probable cause to arrest. Experiment 1 involved 39 sworn law enforcement officers, and experiment 2 involved 43 sworn law enforcement officers and 86 mock detectives. Participants viewed a digital recording depicting a witness describing a gas station robbery (Experiment 1) or a campus mugging (Experiment 2). Witness confidence and detectives' inferences about culprit information influenced the vetting process and lent credibility to a confident witness whose accuracy was objectively unknown. Furthermore, the evidence indicates that sworn law enforcement are comparable with untrained observers in their use of social inference cues (i.e. confidence) in determining witness credibility; however, social inference can be assuaged by the rational, rule‐governed, decision framework established for witness vetting. Social inference processes inherent in the detective‐witness dyad is influenced by legal procedures in vetting witness information. Copyright © 2013 John Wiley & Sons, Ltd.     

The influence of lawyers' questions on witness accuracy,confidence, and reaction times and on mock jurors' interpretation of witness accuracy

Two studies demonstrate the influence of lawyers' complex questions on mock‐witness accuracy, confidence, and reaction times and on the interpretation of witness accuracy by mock jurors. In study one, 32 mock witnesses were shown a short film and then questioned either with lawyers' complex questions or simple alternatives. In Study 2, 20 mock jurors viewed video footage of the mock witnesses assigned to each of the two previous conditions and were asked to rate their confidence in the witnesses' answers. The findings of the two studies indicated that lawyers' use of confusing questions reduce not only accuracy but also speed of response and both witnesses' and jurors' ability to determine accuracy. The implication of these findings is straightforward, lawyers should ask simple questions wherever possible. Copyright © 2010 John Wiley & Sons, Ltd.     

The influence of acoustic similarity on serial recall of letter sequences

Acoustic similarity is known to impair short-term memory (STM) for letter sequences. The present series of experiments investigated the effects of acoustic similarity on long-term retention. In the first experiment, subjects were asked to learn one of two lists of 8 letters, the letters being either of high or low acoustic similarity. Lists were visually presented for three trials, with subjects responding after each trial. Then subjects participated in an immediate memory task for digits which lasted for 20 min. Finally, subjects tried to recall the list of letters they had learned previously. Lists having items of high acoustic similarity were more difficult to recall on the first trial, but were better recalled on the delayed retention test. In a second experiment, groups of subjects were again asked to learn one of two lists of 8 letters differing in acoustic similarity, using different orders of the letters used previously. The procedures were identical except that in two groups, a STM task for digits intervened between the presentation and test of the letters. This intervening task minimized the effects of STM and eliminated the differences in retention found previously. In a third experiment, better long-term retention for material having high acoustic similarity was also obtained when subjects used a backward recall procedure. In the last experiment 14 item lists were learned to a criterion of two correct trials, and retention was tested after each trial and at a delay of 20 min. and 23 hr. No effect of acoustic similarity was found and little retention loss occurred. These results suggest that reducing the STM component by introducing a STM control or by lengthening the list caused the effect of acoustic similarity to disappear.     

The effects of post ‐identification feedback and age on retrospective eyewitness memory

Two studies examined the effects of post‐identification feedback, age, and retention interval on participants' memories and beliefs about memories for a videotaped event, as captured by a store surveillance camera. After viewing the video, they were then asked to identify the suspect from a target‐absent photo line‐up. After making their identification, some participants were given information suggesting that their identification was correct, while others were given no information about the accuracy of their identification. In both experiments participants who received confirming feedback indicated they were more confident in their identification, paid more attention to the video, and that they were more willing to testify in court than those who received no feedback. The confidence inflation effects of post‐identification feedback did not vary with retention interval or age. These results are consistent with a position focusing on accessibility, which suggests that witnesses have little or no retrievable recollection of how sure they were at the time of their identification. Copyright © 2005 John Wiley & Sons, Ltd.     

A comparison of correlation, calibration, and diagnosticity as measures of the confidence-accuracy relationship in witness identification

The relationship between witness confidence and accuracy (CA) has traditionally been measured by the point-biserial correlation (rpb). Recently, 2 alternative indices for measuring the CA relation have been proposed, namely calibration and diagnosticity analyses (e.g., P. Juslin, N. Olsson, & A. Winman, 1996). In this study, the 3 measures were compared quantitatively using 52 independent data sets. The measures rpb and calibration were weakly correlated, whether computed across earwitness data sets, eyewitness data sets, or all data. Thus, when applied to the same data, these 2 measures sometimes yield different conclusions. A modest relation was observed between the rpb and the diagnosticity of confidence. Finally, calibration and degree of over- and underconfidence covaried with task difficulty, consistent with K. A. Deffenbachers' (1980) optimality hypothesis.     

Voice identification of an abductor

A total of 288 male and 288 female undergraduate students heard a taped voice of a mock abductor for a total of 18 seconds, 36 seconds, 120 seconds, or 6 minutes. One-third of all subjects heard the voice for one massed trial, one-third for two equal periods separated by a 5-minute inter-trial interval, and the remainder for three equal periods separated by 5-minute intervals. Voice identification and confidence of response were tested immediately after observation, or 24 hours later, or 1 week later. Hit rates were significantly greater with longer voice-sample durations, and were superior with two distributed exposures to the suspect's voice in contrast to one massed exposure or three distributed exposures. However, the false alarm rate in the suspect-present line-up differed significantly as a function of voice- sample durations and retention intervals, and voice-sample durations and frequency of distributed exposures. False alarms in the suspect-absent line-up were consistently high (overall M = .58) and exceeded the overall hit rate (M = .40). Confidence of response was negatively correlated with suspect identification in the 18-second voice-sample condition, but was positively correlated with voice-sample durations of 120 seconds and 6 minutes.     

Judicial decision making: order of evidence presentation and availability of background information

An experiment was conducted to investigate both the effect of the order of presentation of defence and prosecution evidence and the prior availability of background information on assessment of guilt. Subjects were required to judge the defendant's probability of guilt either after each witness statement (step-by-step) or after having read all witness statements (end-of-sequence). In the step-by-step mode, an order effect was observed with later evidence exerting a greater impact on the subjects' judgment. This recency effect probably occurred because subjects used an anchoring-and-adjustment process: each new piece of evidence was averaged with an anchor judgment reflecting the overall assessment of previous items. In the end-of-sequence mode, on the other hand, the order effect depended on the background condition: if background information was provided a recency effect occurred, but if no background information was available a primacy effect was evident. This result might be explained by assuming that subjects tried to integrate witness information into a coherent cognitive pattern. As the judgment is memory-based in the end-of-sequence condition, recent information will be more available than earlier items. However, when no background information was presented, the first evidence items had to be processed at a more semantic, deeper level, resulting in a primacy effect that apparently outweighed the recency effect. © 1998 John Wiley & Sons, Ltd.     

Typicality effects on memory for voice: Implications for earwitness testimony

The effects of voice typicality on voice recognition were examined. In an incidental task, participants were presented with consonant‐vowel‐consonant stimuli (with varying vowels) spoken by voices rated as high‐typical or low‐typical. One week later, they were brought back for a surprise voice recognition test where the target voice was presented along with low‐typical and high‐typical voice distracters. The results indicated that voice misidentifications occur, with many errors due to confusions of high‐typical voice targets with high‐typical target voices. The results show that voice typicality affects voice recognition accuracy and is an important factor to be considered in real‐life earwitness testimony situations. Copyright © 2009 John Wiley & Sons, Ltd.     

Post‐identification feedback effects: Investigators and evaluators

We investigated the effects of post‐identification feedback and viewing conditions on beliefs and interviewing tactics of participant‐investigators, crime reports of participant‐witnesses and participant‐evaluators' credibility judgments of the witnesses. Study 1 participants assumed the roles of witness and investigator (N = 167 pairs). Witnesses' view of a simulated crime video was manipulated by distance from viewing monitor: 2 or 9 ft. Participants made a line‐up identification and received either positive feedback or no feedback. Significant effects for witnesses and investigators were associated with viewing condition and post‐identification feedback. Interviews between investigator‐witness pairs were videotaped. Investigators asked more positive, leading questions when they were led to believe that the witness had identified the suspect. In Study 2 evaluators (N = 302) viewed the witness‐investigator interviews. Viewing condition had no effect on judgments of witness credibility but positive post‐identification feedback led evaluators to judge witnesses as more credible than witnesses who received no feedback. Copyright © 2010 John Wiley & Sons, Ltd.     

Intuitive extrapolation of a growth function

Abstract.— Subjects were instructed to extrapolate curvilinear functions with time (trial) as the dependent variable. Two power functions were used in the experiment and they were each presented either numerically or graphically as plots. During each trial (representing one year) the subjects were asked to predict the year when a certain value of the dependent variable or event would be reached, plus a 90% confidence interval around this prediction. The results showed that the more curvilinear of the two functions was the more difficult to use for predictions of a future event but that there were no significant differences between predictions involving numerical and graphical presentations. Initially, the subjects gave too wide confidence intervals around their predictions, but as they received more information the estimated confidence intervals became too narrow in relation to their performance.