Assessing the Specificity and Accuracy of Accent Judgments by Lay Listeners.

Historically, there has been less research carried out on earwitness than eyewitness testimony. However, in some cases, earwitness evidence might play an important role in securing a conviction. This paper focuses on accent which is a central characteristic of voices in a forensic linguistic context. The paper focuses on two experiments (Experiment 1, n = 41; Experiment 2, n = 57) carried out with participants from a wide range of various locations around the United Kingdom to rate the accuracy and confidence in recognizing accents from voices from England, Scotland, Wales, Northern Ireland, and Ireland as well as looking at specificity of answers given and how this varies for these regions. Our findings show that accuracy is variable and that participants are more likely to be accurate when using vaguer descriptions (such as "Scottish") than being more specific. Furthermore, although participants lack the meta-linguistic ability to describe the features of accents, they are able to name particular words and pronunciations which helped them make their decision.

Evaluating earwitness identification procedures: adapting pre-parade instructions and parade procedure.

Voice identification parades can be unreliable, as earwitness responses are error-prone. In this paper we tested performance across serial and sequential procedures, and varied pre-parade instructions, with the aim of reducing errors. The participants heard a target voice and later attempted to identify it from a parade. In Experiment 1 they were either warned that the target may or may not be present (standard warning) or encouraged to consider responding "not present" because of the associated risk of a wrongful conviction (strong warning). Strong warnings prompted a conservative criterion shift, with participants less likely to make a positive identification regardless of whether the target was present. In contrast to previous findings, we found no statistically reliable difference in accuracy between serial and sequential parades. Experiment 2 ruled out a potential confound in Experiment 1. Taken together, our results suggest that adapting pre-parade instructions provides a simple way of reducing the risk of false identifications.

Voice parade procedures: optimising witness performance.

Unfamiliar voice identification is error-prone. Whilst the investigation of system variables may indicate ways of boosting earwitness performance, this is an under-researched area. Two experiments were conducted to investigate how methods of presenting voices during a parade affect accuracy and self-rated confidence. In each experiment participants listened to a target voice, and were later asked to identify that voice from a nine-person target present or target absent parade. In Experiment 1, accuracy did not vary across parades comprising 15 or 30 s sample durations. Overall, when the target was present, participants correctly identified the target voice with 39% accuracy. However, when the target was absent, participants correctly rejected the parade 6% of the time. There was no relationship between accuracy and confidence. In Experiment 2, performance with a serial procedure, in which participants responded after hearing all nine voices, was compared with a sequential procedure, in which participants made a decision after listening to each voice. Overall accuracy was higher with the sequential procedure. These results highlight the importance of system variable research in voice identification. Different methods of presenting voices have the potential to support higher levels of accuracy than the procedure currently recommended in England and Wales.

What underlies the neuropsychological pattern of irregular > regular past-tense verb production?

The disadvantage in producing the past tense of regular relative to irregular verbs shown by some patients with non-fluent aphasia has been alternatively attributed (a) to the failure of a specific rule-based morphological mechanism, or (b) to a more generalised phonological impairment that penalises regular verbs more than irregular owing to the on-average greater phonological complexity of regular past-tense forms. Guided by the second of these two accounts, the current study was designed to identify more specific aspects of phonological deficit that might be associated with the pattern of irregular > regular past-tense production. Non-fluent aphasic patients (N = 8) were tested on past-tense verb production tasks and assessed with regard to the impact of three main manipulations in other word-production tasks: (i) insertion of a delay between stimulus and response in repetition; (ii) presence/number of consonant clusters in a target word in repetition; (iii) position of stress within a bi-syllabic word in repetition and picture naming. The performance of all patients deteriorated in delayed repetition; but the patients with the largest discrepancy between regular and irregular past-tense production showed greater sensitivity to the other two manipulations. The phonological nature of the factors that correlated with verb-inflection performance emphasises the role of a phonological deficit in the observed pattern of irregular > regular.

The relationship between phonological and morphological deficits in Broca's aphasia: further evidence from errors in verb inflection.

A previous study of 10 patients with Broca's aphasia demonstrated that the advantage for producing the past tense of irregular over regular verbs exhibited by these patients was eliminated when the two sets of past-tense forms were matched for phonological complexity (Bird, Lambon Ralph, Seidenberg, McClelland, & Patterson, 2003). The interpretation given was that a generalised phonological impairment was central to the patients' language deficits, including their poor performance on regular past tense verbs. The current paper provides further evidence in favour of this hypothesis, on the basis of a detailed analysis of the errors produced by these same 10 patients in reading, repetition, and sentence completion for a large number of regular, irregular, and nonce verbs. The patients' predominant error types in all tasks and for all verb types were close and distant phonologically related responses. The balance between close and distant errors varied along three continua: the severity of the patient (more distant errors produced by the more severely impaired patients); the difficulty of the task (more distant errors in sentence completion>reading>repetition); the difficulty of the item (more distant errors for novel word forms than real verbs). A position analysis for these phonologically related errors revealed that vowels were most likely to be preserved and that consonant onsets and offsets were equally likely to be incorrect. Critically, the patients' errors exhibited a strong tendency to simplify the phonological form of the target. These results are consistent with the notion that the patients' relatively greater difficulty with regular past tenses reflects a phonological impairment that is sensitive to the complexity of spoken forms.