Magnocellular facilitation of flanked-letter identification disappears with strong flanker interference

Previously, we obtained evidence to suggest that the magnocellular system may reduce interference from flankers during flanked-letter identification. To understand this phenomenon better, we combined the data of our previous experiments, which all used the same flanking letter, and focused on the different target letters that were used. The new analysis showed that after an initial increase, magnocellular facilitation decreased and ultimately disappeared, as the target–flanker combination's level of interference increased. The initial increase was partly while the later decrease was fully replicated in two new experiments that focused on two different target letters while manipulating flanker identity. The outcome of a third new experiment studying the type of interference reduced suggested that although crowding contributed to total interference, it was insensitive to magnocellular mediation. Our results may be understood to reflect the involvement of the magnocellular system in an attentional-selection mechanism that is silenced by surround suppression.     

Three layers of working memory: Focus-switch costs and retrieval dynamics as revealed by the N-count task

Two experiments explored the process of switching items in and out of the focus of attention using a new paradigm, the N-count task (adapted from Garavan, 1998; N varied from 1 to 4). This task yielded a focus size of one, indicated by a substantial focus-switch cost for 2-count. Additionally, the focus-switch costs in response time increased with working memory load, indicating an effortful search process occurring at a speed of about 240 ms/item. Maintaining and switching to and from a passive load did not increase the focus-switch costs or decrease memory accuracy, indicating that there is no crosstalk between passive and active items. The results support a concentric theory of working memory: a small focus at its core, a surrounding area of (at least) three readily available items referred to as the outer store, and a still wider region of passive storage, possibly more long-term memory than working memory.     

A focused attention intervention for coping with ostracism

Ostracism—being excluded and ignored—thwarts satisfaction of four fundamental needs: belonging, self-esteem, control, and meaningful existence. The current study investigated whether training participants to focus their attention on the here-and-now (i.e., focused attention) reduces distress from an ostracism experience. Participants were first trained in either focused or unfocused attention, and then played Cyberball, an online ball-tossing game for which half the participants were included or ostracized. Participants reported their levels of need satisfaction during the game, and after a short delay. Whereas both training groups experienced the same degree of need-threat in the immediate measure, participants who were trained in focused attention showed more recovery for the delayed measure. We reason that focused attention would not reduce the distress during the ostracism experience, but it aided in recovery by preventing participants from reliving the ostracism experience after it concludes.     

The contributions of arousal and self-focused attention to avoidance in social anxiety

Abstract

Fear of blushing is a specific syndrome generally subsumed under the diagnostic category of social anxiety disorder (SAD). This study aims at gathering preliminary data about an intensive weekend intervention specifically designed for individuals with fear of blushing as the predominant complaint. Treatment consisted of a combination of attention training and behavioral therapy. Thirty-one blushing-fearful individuals meeting the criteria for SAD following the Diagnostic and Statistical Manual of Mental Disorders IV (DSM-IV) were treated in three groups. The study was conducted as an open trial. Full assessments were performed before treatment, six weeks after treatment, and at six-month follow-up. Only fear of blushing, the main outcome criterion, was assessed immediately before and after the treatment weekend. The intensive therapy program was well accepted. Fear of blushing and SAD were significantly reduced and reductions remained stable. At follow-up, nearly two-thirds of the participants achieved significant changes in fear of blushing. Despite the preliminary nature of this study, the condensed format of weekend therapy for treating fear of blushing calls for further investigation.     

Sustained attention can create an (illusory) experience of seeing dynamic change

Recent studies speculated that two types of change detection exist, one involving the experience of seeing dynamic change (change over brief interval), the other involving detecting a completed change (change over long interval), with only the former requiring sustained attention. To examine this supposition, a flicker change detection task was conducted in which the spatial location of objects was manipulated (shift, no-shift). In shift conditions, changed image display appeared in different locations than they did in the original display. The time interval separating images was manipulated (200 or 1000 ms). Results showed that a shift led to poor change detection only in the short interval condition. The performance decline by the image shift was not attenuated even when participants knew beforehand whether or not a shift would occur. Results indicate that sustained attention, which is sustained for a brief time, is related to the experience of seeing dynamic change.     

Masked partial priming of letter perception

In three experiments testing 178 subjects, letter targets were preceded by briefly presented, pattern-masked primes formed by deleting pixels in a larger or smaller version of the target stimulus. In Experiment 1A (alphabetic decision)and Experiment 1B (letter naming) a slight advantage was observed for global primes (alternate pixels deleted) compared with junction primes (midsegment information removed). This advantage was stronger at 50 ms prime exposures than at 30 ms exposures in the naming task. In Experiment 2 (letter naming), midsegment primes (with junction information removed) produced faster latencies than did junction primes. This result was replicated in a third experiment and was shown to be independent of target letter case and the relative size of prime and target stimuli. The same midsegment and junction primes did not facilitate performance compared to neutral primes in the alphabetic decision task. These results suggest that masked partial priming of letter naming can be usefully applied to the study of basic processes in letter perception.     

A new form of human spatial attention: Automated symbolic orienting

The control of human attention is typically conceptualized either in terms of exogenous automatic processes that are driven by external sensory stimulation or endogenous strategic processes that are driven by internal expectancies about events in the environment. However, this classic dichotomy has struggled to explain a wealth of new data demonstrating that behaviourally and biologically relevant visual stimuli, like arrow and eye direction, elicit shifts of spatial attention that on the one hand, appear exogenous, and on the other hand, endogenous. To address this issue, we used a double-cueing task that combined arrows with classic cues known to invoke either exogenous or endogenous orienting. Our data suggest that behaviourally relevant directional cues, like arrows, engage a new form of cortically mediated orienting—automated symbolic orienting—that operates independent of, and in parallel with, the two classic forms of exogenous and endogenous spatial attention.     

Visual target detection is impaired at event boundaries

Boundaries between meaningful events are key moments in comprehending human action. At these points, viewers may focus on the event's contents at the expense of other information. We tested whether visual detection was impaired at those moments perceivers judged to be boundaries between events. Short animated football clips were used as stimulus material, and event boundaries were imposed by having the ball change possession. In a first experiment, we found that possession changes were perceived to be event boundaries. In a second experiment, participants were asked to keep track of 4 of 10 players and to watch for 120 ms probes appearing either at an event boundary or a nonboundary. Probe detection was less accurate at event boundaries. This result suggests that the segmentation of ongoing activity into events corresponds with the regulation of attention over time.     

The role of prior exposure in the capture of attention by items in working memory

The Biased Competition Model (BCM) suggests both top-down and bottom-up biases operate on selective attention (e.g., Desimone & Duncan, 1995). It has been suggested that top-down control signals may arise from working memory. In support, Downing (2000) found faster responses to probes presented in the location of stimuli held vs. not held in working memory. Soto, Heinke, Humphreys, and Blanco (2005) showed the involuntary nature of this effect and that shared features between stimuli were sufficient to attract attention. Here we show that stimuli held in working memory had an influence on the deployment of attentional resources even when: (1) It was detrimental to the task, (2) there was equal prior exposure, and (3) there was no bottom-up priming. These results provide further support for involuntary top-down guidance of attention from working memory and the basic tenets of the BCM, but further discredit the notion that bottom-up priming is necessary for the effect to occur.     

Look who's talking? Sound changes gaze behaviour in a dynamic social scene

Humans often look at other people in natural scenes, and previous research has shown that these looks follow the conversation and that they are sensitive to sound in audiovisual speech perception. In the present experiment, participants viewed video clips of four people involved in a discussion. By removing the sound, we asked whether auditory information would affect when speakers were fixated, how fixations between different observers were synchronized, and whether the eyes or mouth were looked at most often. The results showed that sound changed the timing of looks—by alerting observers to changes in conversation and attracting attention to the speaker. Clips with sound also led to greater attentional synchrony, with more observers fixating the same regions at the same time. However, looks towards the eyes of the people continued to dominate and were unaffected by removing the sound. These findings provide a rich example of multimodal social attention.