Children's working-memory processes: a response-timing analysis

Recall response durations were used to clarify processing in working-memory tasks. Experiment 1 examined children's performance in reading span, a task in which sentences were processed and the final word of each sentence was retained for subsequent recall. Experiment 2 examined the development of listening-, counting-, and digit-span task performance. Responses were much longer in the reading-and listening-span tasks than in the other span tasks, suggesting that participants in sentence-based span tasks take time to retrieve the semantic or linguistic structure as cues to recall of the sentence-final words. Response durations in working-memory tasks helped to predict academic skill and achievement, largely separate from the contributions of the memory spans themselves. Response durations thus are important in the interpretation of span task performance.     

Does the right hemisphere take over after damage to Broca's area? the Barlow case of 1877 and its history

In 1877 Thomas Barlow, a London physician, published a remarkable case of functional recovery of speech following brain damage. It involved a 10-year-old boy who had lost his speech, regained it, and lost it again before he died from a disorder that affected his heart and produced embolisms that subsequently affected other organs, including his brain. Examination of the boy's brain revealed two focal regions of softening; one that affected Broca's area and the left facial-motor area, and another, which occurred weeks later, in the homologous regions of the right hemisphere. Although Barlow was most concerned with motor deficits, others at the turn of the century began to cite this case as strong evidence that the corresponding region of the right hemisphere can take over speech functions for Broca's area on the left. Whether this case really provides good support for functional takeover or vicariation theory is critically evaluated in the light of contemporary research, including PET scan studies involving damage to Broca's speech region.     

Facilitation and disruption of lateralized syllable processing by unattended stimuli in the opposite visual field

The influence of lateralized unattended stimuli on the processing of attended stimuli in the opposite visual field can shed light on the nature of information that is transferred between hemispheres. On a cued bilateral task, participants tried to identify a syllable in the attended visual field, which elicits a left hemisphere (LH) advantage and different processing strategies by the two hemispheres. The same or a different syllable or a neutral stimulus appeared in the unattended field. Transmission of unattended syllable codes between hemispheres is symmetric, as revealed by equal interference for the two visual fields. The LH is more accurate than the RH in encoding unattended syllables, as indicated by facilitation in the left but not right visual field and a greater frequency of identifiable intrusions into the left than right field. However, asymmetric encoding strategies are different for attended and unattended syllables.     

The neural basis of autobiographical and semantic memory: new evidence from three PET studies

A novel, neuropsychologically informed paradigm (extended retrieval of events in response to a cue word) was used to investigate the neural basis of autobiographical and semantic memory. Contrasting retrieval of autobiographical memories with retrieval of semantic facts (ABM-SEM) in 24 subjects across three PET studies revealed bilateral involvement of the middle temporal gyrus (BA 21) and medial frontal cortex (BA 9/10). The opposite contrast, SEM-ABM, resulted in increased regional cerebral blood flow in left posterior temporal regions (BA 37) and left prefrontal cortex (BA 45/46). Laterality maps suggest that the bilateral pattern seen in our studies, but not often in other neuroimaging investigations, reflects the use of a task stressing retrieval of specific personal events. Further comparisons revealed that the activation in the right anterior temporal lobe during autobiographical recall was virtually identical to that seen during retrieval of information about famous people or events in contrast with retrieval of general semantic facts. These findings suggest that the retrieval of an autobiographical event requires participation from conceptual knowledge, and that this type of knowledge is bilaterally distributed in the temporal lobes.     

Effectiveness of the Hamilton Anxiety Rating Scale with Older Generalized Anxiety Disorder Patients

To expand the collection of instruments available for assessment of anxiety in the elderly, this report examined the original and revised Hamilton anxiety scales in a sample of 50 older adults diagnosed with Generalized Anxiety Disorder (GAD) and 93 normal community participants (ages 55–82). Although the revised anxiety scale had better discriminant validity (lower correlation with the revised Hamilton depression scale) than the original anxiety and depression scales, a considerable amount of shared variance still existed (41% shared variance, GAD sample alone; 17% control sample alone; 74% shared variance, both samples combined). Near-perfect group classification was possible using 7 items from the original anxiety scale and 10 items from the revised anxiety scale. Results are discussed in light of their implications for use of the Hamilton anxiety rating scale with older anxiety-disordered patients.     

Reversing the phonological similarity effect

The phonological similarity effect--poor retention of order for lists of similar-sounding items--is a benchmark finding in the short-term memory literature. In our first two experiments, we show that the effect actually reverses following relatively brief periods of distraction, yielding better order retention for similar than for dissimilar lists, provided that different items are used on every trial. In Experiment 3, the same items were used on every trial and similar lists produced poorer performance across all three retention intervals. The results are interpreted from a general discrimination framework: Items are viewed as occupying positions in a multidimensional space defined by list and within-list dimensions.     

The Dimensionality of Memory Strength Between Levels of Both Serial Position and Word Frequency Category

In recognition tasks where Signal Detection Theory (SDT) is applied, a suitable decision variable is required. This variable is typically assumed to be a global assessment of memory strength. A further assumption is that factors such as old-new, serial position (SP), and word frequency (WF) simply act to change the value of strength across levels within the factor. In terms of SDT, the decision variable is assumed to be uni-dimensional. Four experiments are reported that provide a direct empirical assessment of this assumption for SP and WF. Judgements of items (JOI), recency (JOR), and primacy (JOP) were measured for SP; and subjective frequency (JOF) was measured for WF. Multiple dimensions imply non-additive effects across factor levels and different retrieval processes or the influence of an extra process. A single dimension is consistent with an additive effect of factor levels and current theorizing. The data are in fairly good agreement with the uni-dimensional assumption across all four factors with the exception of JOR and JOP. These showed less uni-dimensionality for comparisons between beginning vs. end list items. The implications of this are discussed.     

The Sigmund Freud Museum Exhibit: The Price for a Bit of Good Luck

The Museum Exhibit on the life and works of Sigmund Freud and psychoanalysis opened at the Library of Congress in Washington, DC on October 15, 1998. The Exhibit includes both praise and critical commentary regarding Freud's many contributions. Original documents, artifacts and personal items from Freud collections are on display as well as film clips, photographs, and other recordings. Different periods in Freud's life are highlighted. After leaving Washington, DC, the Exhibit will travel to New York, Los Angeles, and on to Vienna.     

Book reviews

Classical Probability in the Enlightenment. LORRAINE DASTON, 1988. Princeton, Princeton University Press. xviii + 423 pp., US$19.95 (paperback). ISBN 0–691–08497–1, 0–691–00644‐X (paperback)

Following Form and Function: a Philosophical Archaeology of Life Science. STEPHEN T. ASMA, 1996. Evanston, IL, Northwestern University Press. xiii + 232 pp., price not available

Concepts and Methods in Evolutionary Biology. ROBERT N. BRANDON, 1996. Cambridge, Cambridge University Press. xiv+221 pp., $US59.95 (hardback), $Can 27.50 (paperback). ISBN 0–521–49545–9 (hardback), 0–521–49888–0 (paperback)

The Completeness of Scientific Theories: on the Derivation of Empirical Indicators within a Theoretical Framework: the Case of Physical Geometry. The University of Western Ontario Series in Philosophy of Science, Volume 53. MARTIN CARRIER, 1994. Dordrecht, Kluwer. xviii + 248 pp., price not available. ISBN 0–7923–24757 (hardback)

The Philosophy and History of Molecular Biology: New Perspectives. Boston Studies in the Philosophy of Science, Volume 183. SAHOTRA SARKAR (Ed.), 1996. Dordrecht, Kluwer. 264 pp., $US127. ISBN 0–7923–3947–9

Awareness: What it is, What it does. CHRIS NUNN, 1996. London and New York, Routledge. price not available. ISBN 0–415–13227–4