Attention scaling modulates the effective capacity of visual sensory memory.

Visual sensory memory (VSM) has a high capacity, but its contents are fleeting. Recent evidence that the breadth of attention strongly influences the efficiency of visual processing suggests that it might also modulate the effective capacity of VSM. We manipulated the breadth of attention with different cue sizes and used the partial-report technique to estimate the capacity of VSM.

Tracking the will to attend: Cortical activity indexes self-generated, voluntary shifts of attention.

The neural substrates of volition have long tantalized philosophers and scientists. Over the past few decades, researchers have employed increasingly sophisticated technology to investigate this issue, but many studies have been limited considerably by their reliance on intrusive experimental procedures (e.g.

Attending to illusory differences in object size.

Focused visual attention can be shifted between objects and locations (attentional orienting) or expanded and contracted in spatial extent (attentional focusing). Although orienting and focusing both modulate visual processing, they have been shown to be distinct, independent modes of attentional control. Objects play a central role in visual attention, and it is known that high-level object representations guide attentional orienting.

Deconstructing spatial working memory and attention deficits in multiple sclerosis.

Objective: To investigate whether spatial working memory (WM) is impaired in multiple sclerosis (MS), and, if it is, to localize impairment to specific cognitive subprocess(es).

Method: In Experiment 1, MS and control participants performed computerized memory-span and visuomotor tasks. WM subprocesses were taxed by manipulating (1) the requirement to remember serial order, (2) delay duration, and (3) the presence of irrelevant stimuli during target presentation.

Tracking cognitive fluctuations with multivoxel pattern time course (MVPTC) analysis.

The posterior parietal cortex, including the medial superior parietal lobule (mSPL), becomes transiently more active during acts of cognitive control in a wide range of domains, including shifts of spatial and nonspatial visual attention, shifts between working memory representations, and shifts between categorization rules. Furthermore, spatial patterns of activity within mSPL, identified using multivoxel pattern analysis (MVPA), reliably distinguish between different acts of control. Here we describe a novel multivoxel pattern-based analysis that uses fluctuations in cognitive state over time to reveal inter-regional functional connectivity.

Configural representations in spatial working memory: modulation by perceptual segregation and voluntary attention.

In what form are multiple spatial locations represented in working memory? The present study revealed that people often maintain the configural properties (interitem relationships) of visuospatial stimuli even when this information is explicitly task-irrelevant. However, the results also indicated that the voluntary allocation of selective attention prior to stimulus presentation, as well as feature-based perceptual segregation of relevant from irrelevant stimuli, can eliminate the influence of stimulus configuration on location-change detection performance. In contrast, voluntary attention cued to the relevant target location following presentation of the stimulus array failed to attenuate these influences.

Binding serial order to representations in working memory: a spatial/verbal dissociation.

Verbal information is coded naturally as ordered representations in working memory (WM). However, this may not be true for spatial information. Accordingly, we used memory span tasks to test the hypothesis that serial order is more readily bound to verbal than to spatial representations.

Age differences in the neural representation of working memory revealed by multi-voxel pattern analysis.

Working memory function declines across the lifespan. Computational models of aging attribute such memory impairments to reduced distinctiveness between neural representations of different mental states in old age, a phenomenon termed dedifferentiation. These models predict that neural distinctiveness should be reduced uniformly across experimental conditions in older adults.

Age differences in prefontal recruitment during verbal working memory maintenance depend on memory load.

Positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) studies have revealed age-related under-activation, where older adults show less regional brain activation compared to younger adults, as well as age-related over-activation, where older adults show greater activation compared to younger adults. These differences have been found across multiple task domains, including verbal working memory (WM). Curiously, both under-activation and over-activation of dorsolateral prefrontal cortex (DLPFC) have been found for older adults in verbal WM tasks.

Strategic modulation of the fixation-offset effect: dissociable effects of target probability on prosaccades and antisaccades.

In several previous experiments examining the effects of participants' expectations on oculomotor performance, the manipulation of target probability has been confounded with factors such as target occurrence and saccade frequency. We report results from three experiments that manipulated target probability in isolation from systematic variations in such bottom-up factors. We present evidence for trial-by-trial, top-down modulation of the fixation-offset effect in prosaccade latency.