The cost in remembering of ruminating on negative memories

This study investigated retrieval mechanisms that may be involved in memory for distressing stimuli. Forty-one nonclinical participants watched a video clip depicting the immediate aftermath of a serious car accident. Following this, half of the participants were instructed to focus attention on the victims of the accident and to consider the negative sequelae of their injuries. The remaining participants were not given any instructions. Following the Victim Focus/Control period, all participants completed a cued-recall task assessing their memory of the video clip. Overall, victim-related details were better recalled than nonvictim related details. It is important to note that participants in the Victim Focus condition retrieved fewer peripheral details than participants in the Control condition. These results suggest that people focusing attention on distressing aspects of an event can experience a cost in remembering other aspects of the event. These findings may be interpreted in terms of enhanced recollection of central events or retrieval-induced forgetting mechanisms to explain patterns of diminished memory for aspects of distressing events.     

Rapid modulation of distributed brain activity by Transcranial Magnetic Stimulation of human motor cortex

This paper reviews the effects of single and repetitive transcranial magnetic stimuli (rTMS) delivered to one cortical area and measured across distributed brain regions using electrophysiological measures (e.g. motor thresholds, motor evoked potentials, paired-pulse stimulation), functional neuroimaging (including EEG, PET and fMRI) and behavioural measures. Discussion is restricted to changes in excitability in the primary motor cortex and behaviour during motor tasks following transcranial magnetic stimulation delivered to primary motor and premotor areas. Trains of rTMS have lasting effects on the excitability of intrinsic and corticofugal neurones, altering the responsiveness of local and remote sites. These effects lead to distributed changes in synaptic activity at rest, and during a range of motor tasks. It is possible to impair or improve performance following rTMS, but for most simple motor tasks performance is unaltered. Changes in distributed activity observed with functional imaging during motor behaviour may represent compensatory activity, enabling maintenance of performance; stimulation of additional cortical areas appears to impair performance. A detailed understanding of the distributed changes in excitability following rTMS may facilitate future attempts to modulate motor behaviour in the healthy brain and for therapeutic purposes.     

Tactile sensitivity in Asperger syndrome

People with autism and Asperger syndrome are anecdotally said to be hypersensitive to touch. In two experiments, we measured tactile thresholds and suprathreshold tactile sensitivity in a group of adults with Asperger syndrome. In the first experiment, tactile perceptual thresholds were measured. Two frequencies of vibrotactile stimulation were used: 30 and 200 Hz. The results demonstrated significantly lower tactile perceptual thresholds in the Asperger group at 200 Hz but not at 30 Hz, thus confirming tactile hypersensitivity but only for one class of stimulus. A second experiment investigated whether self-produced movement affected the perception of touch in a group of adults with Asperger syndrome. A suprathreshold tactile stimulus was produced either by the participant (self-produced condition) or by the experimenter (externally produced condition) and participants were asked to rate the perception of the tactile stimulation. The results demonstrated that, while both Asperger and control groups rated self-produced touch as less tickly than external touch, the Asperger group rated both types of tactile stimulus as significantly more tickly and intense than did the control group. This experiment confirms the finding of tactile hypersensitivity, but shows that the perceptual consequences of self-produced touch are attenuated in the normal way in people with Asperger syndrome. An abnormality in this process cannot therefore account for their tactile hypersensitivity.     

Effects of category diversity on learning,memory, and generalization

In this study, we examined the effect of within-category diversity on people's ability to learn perceptual categories, their inclination to generalize categories to novel items, and their ability to distinguish new items from old. After learning to distinguish a control category from an experimental category that was either clustered or diverse, participants performed a test of category generalization or old-new recognition. Diversity made learning more difficult, increased generalization to novel items outside the range of training items, and made it difficult to distinguish such novel items from familiar ones. Regression analyses using the generalized context model suggested that the results could be explained in terms of similarities between old and new items combined with a rescaling of the similarity space that varied according to the diversity of the training items. Participants who learned the diverse category were less sensitive to psychological distance than were the participants who learned a more clustered category.     

Social cognitive neuroscience: where are we heading?

Humans crave the company of others and suffer profoundly if temporarily isolated from society. Much of the brain must have evolved to deal with social communication and we are increasingly learning more about the neurophysiological basis of social cognition. Here, we explore some of the reasons why social cognitive neuroscience is captivating the interest of many researchers. We focus on its future, and what we believe are priority areas for further research.     

Redintegration and lexicality effects in children: Do they depend upon the demands of the memory task?

The effect of long-term knowledge upon performance in short-term memory tasks was examined for children from 5 to 10 years of age. The emergence of a lexicality effect, in which familiar words were recalled more accurately than unfamiliar words, was found to depend upon the nature of the memory task. Lexicality effects were interpreted as reflecting the use of redintegration, or reconstruction processes, in short-term memory. Redintegration increased with age for tasks requiring spoken item recall and decreased with age when position information but not naming was required. In a second experiment, redintegration was found in a recognition task when some of the foils rhymed with the target. Older children were able to profit from a rhyming foil, whereas younger children were confused by it, suggesting that the older children make use of sublexical phonological information in reconstructing the target. It was proposed that redintegrative processes in their mature form support the reconstruction of detailed phonological knowledge of words.     

Similarity as transformation

We propose that similarity is determined by the transformation distance between representations: entities which are perceived to be similar have representations which are readily transformed into one another, whereas transforming between dissimilar entities requires many transformations. We present three experiments that indicate that similarity is strongly influenced by transformation distance. These data present a challenge for featural or spatial accounts of similarity. Finally, we introduce a family of transformation-based accounts of similarity, called 'Representational Distortion', as a specific example of a transformational approach to similarity.     

Using auditory streaming to reduce disruption to serial memory by extraneous auditory warnings

Three experiments were conducted to examine the effects of extraneous speech warnings (i.e., low-priority warnings initiated during high-priority tasks) on cognitive performance and whether organizing the auditory warnings into streams can attenuate any disruption. Experiment 1 demonstrated that a variety of speech warnings can be separated into perceptually distinct streams by allocating them to discrete spatial locations. Experiment 2 showed that increasing the rate of presentation of the warnings to promote streaming decreased clarity ratings but increased perceived urgency ratings. Experiment 3 demonstrated that the disruption to serial memory for navigational information by extraneous speech warnings could be attenuated by streaming. Results are interpreted in light of previous research, and practical implications for auditory warning design are discussed.