Earwitness Testimony: Never Mind the Variety,Hear the Length

Three aspects of voice recognition were investigated in the study reported here: memory for familiar voices, memory for the words spoken, and the relative effects of length and variation in a voice extract on long- and short-term memory. In Experiment 1, recognition memory for the briefly heard voice of a stranger was superior with longer extracts (p<0.01), but increasing vowel variety did not improve performance. This pattern was repeated for short-term memory (p<0.01) in Experiment 2. Scores for the above task correlated significantly (p<0.05) with scores for recognizing well-known voices. In a further test of well-known voice memory in Experiment 3, a weak and non-significant positive correlation (r=0.29) was found between memory for well-known voices and memory for a once-heard voice. Memory for the words spoken did not correlate significantly with memory for the unknown voice itself. The possibilities of a memory-for-voices general ability, and forensic applications of the findings are discussed. © 1997 by John Wiley & Sons, Ltd.     

Retrieval processing and episodic memory

The emergence of brain imaging has had a major impact on research into the cognitive and neural bases of human memory. An area in which this impact has been particularly strong is retrieval processing - the processes engaged when attempting to retrieve information during a memory test. Several different classes of retrieval process - such as 'mode', 'effort' and 'success' - have been invoked to account for findings from neuroimaging studies of episodic retrieval. In this article we discuss how these different kinds of process, along with a fourth kind associated with 'retrieval orientation', can be investigated in brain imaging experiments. We then review studies of retrieval processing, and assess how well their designs match up to our proposed criteria for dissociating the neural correlates of different classes of retrieval process. We conclude that few studies have used designs that permit these different kinds of process to be independently identified, and that presently there is little evidence to indicate which kinds of processing can be fractionated in terms of their neural correlates.     

Developmental dyslexics do not fit in boxes: Evidence from six new case studies

Abstract

Six subjects with a reading problem were tested on a variety of reading and other tasks including tests of phonological awareness and processing, short-term memory, visual analysis and synthesis, memory for faces and pictures, and matching of letters and shapes. The subjects demonstrated differences in their reading strategies, but these showed no relation to any differences in the patterns of deficit on non-reading tasks. Five of them showed severe problems on tasks involving phonological processing and short-term memory but the seventy of these was unrelated to reading strategy. There were some indications of visual weaknesses, but these were severe in only one subject who had a pronounced defect in memory for faces; there was no evidence that the visual weaknesses were consistently related to reading ability or strategy.

It is concluded that all the subjects in this sample (with one 'possible exception) had a deficit in phonological processing but adopted different strategies to cope with this when faced with the task of converting print to sound. Differences in strategy are likely to be affected by the relative efficiency of other cognitive processes, personality and introdctional factors.     

An event-related potential study of the revelation effect

Event-related potentials (ERPs) were recorded during a verbal recognition memory task in order to investigate whether changes in familiarity are part of the explanation for the revelation effect. For half of the test words, participants solved an anagram prior to making the old/new recognition judgment. A revelation effect was obtained: When test words were preceded by the anagram task, a higher probability of an old response was associated with the items than was otherwise the case. The ERPs recorded time-locked to the onset of the test words were separated according to old/new status andthe presence/absence of the anagram task. The ERP index of familiarity was of lower amplitude for both old and new items that were preceded by the anagram task. These findings are consistent with the view that part of the explanation for the revelation effect is a reduction in the familiarity of the critical test items.     

Separating item-related electrophysiological indices of retrieval effort and retrieval orientation

The relationship between two classes of retrieval process-retrieval orientation and retrieval effort-was investigated using electrophysiological (ERP) and behavioural measures. ERPs were recorded during retrieval phases of exclusion tasks in which participants focused on retrieval of either phonological or semantic associates that were generated in a prior study phase. Participants were separated into two groups on the basis of the relative accuracy of their memory judgments in the retrieval tasks (high vs. low relative difficulty) as a means of assessing retrieval effort. The critical contrasts were between the ERPs evoked by unstudied test items separated according to group and emphasis of the retrieval task (semantic vs. phonological). Reliable differences according to task were evident in the high relative difficulty group only. This finding is consistent with the view that, for this task pair at least, ERPs are sensitive to the processes set in train in pursuit of task relevant information (retrieval orientations) only when relative difficulty is high.     

Relations between life difficulties, measures of working memory operation, and examination performance in a student sample

This study investigated the hypothesis that the negative effect of life difficulties on examination performance in university students (Andrews & Wilding, 2004) can be explained by impairment of working memory efficiency. UK-based students were given an extensive interview covering recent life stressors, and carried out a task testing working memory span, in which they had to judge the truth of arithmetic expressions while retaining words. Students reporting one or more life difficulties in the preceding 12 months recalled significantly fewer words than those reporting no such difficulties, but showed no difference in processing time on the task. However, while the number of words recalled was unrelated to examination performance at the end of the year, students who took longer on the task did significantly less well in the examination. This relation was more marked in Science than in Arts students. A number of possible explanations for this pattern of results are considered, which need to be explored in further research. In particular it is suggested that the number of words retained in the working memory span task reflects current state, and is reduced by intrusive thoughts provoked by current life difficulties, while time on the task reflects more permanent efficiency of the processing system and, therefore, efficiency in study and examinations.     

Is attention impaired in ADHD?

Explanations of Attention Deficit Hyperactivity Disorder (ADHD) in terms of a weakness in Executive Function (EF) or related concepts, such as inhibition, are briefly reviewed. Some alternative views are considered, in particular a proposal by Manly and others that ADHD is a weakness primarily of sustained attention (plus control of attention), but not of selective attention, as measured by the Test of Everyday Attention in Children (TEA-Ch; Manly et al., 2001). The underlying structure of the TEA-Ch is analysed and it is concluded that the distinction between selective attention, sustained attention, and control of attention in this battery is not well-founded. Furthermore, evidence from studies by Wilding and others, from visual search tasks similar to those employed by Manly et al. to measure selective attention, demonstrates that, while unimpaired- and impaired-attention groups do not differ in speed of performance on such tasks (the measure employed in the TEA-Ch), they do differ reliably in accuracy. Available evidence from other visual search tasks comparing such groups is reviewed and found to be inconsistent. An attempt is made to resolve the inconsistencies and it is suggested that search tasks including demands that engage EF processes are more likely to demonstrate differences between these groups. It is concluded therefore that the most plausible explanation at present of impaired attention is in terms of weaknesses in EF. Suggestions for improving the precision and detail of this type of explanation are offered.     

The Relationship Between Measures of Cognitive Attention and Behavioral Ratings of Attention in Typically Developing Children

In the present study, we explored the relation between performance on cognitive measures of attention (selection, sustained, and control) and behavioral ratings of inattention and hyperactivity in a sample of typically developing children aged 3 to 7 years. We also examined the influence of chronological age and IQ on both task performance and behavior ratings. Four well-documented attention paradigms were employed, the Visearch (single-target search) task as a measure of selective attention, the Continuous Performance Test (CPT) as a measure of sustained attention, the Day-Night task as a measure of response inhibition, and the Visearch (dual-target search) task as a measure of inhibitory control. The Conners' Rating Scales (Cognitive/Inattention and Hyperactivity subscales) were used to allow for a finer tuned comparison of cognitive performance as related to inattentive behaviors versus hyperactive behaviors. Findings indicate that accuracy and speed in the Visearch dual search task were the most sensitive measures relating respectively to inattentive and hyperactive rated behaviors.