75 research outputs found
Functional imaging reveals working memory and attention interact to produce the attentional blink
Get PDFCopyright @ 2012 Massachusetts Institute of Technology PressIf two centrally presented visual stimuli occur within approximately half a second of each other, the second target often fails to be reported correctly. This effect, called the attentional blink (AB; Raymond, J. E., Shapiro, K. L., & Arnell, K. M. Temporary suppression of visual processing in an RSVP task: An attentional blink? Journal of Experimental Psychology, Human Perception and Performance, 18, 849-860, 1992], has been attributed to a resource "bottleneck," likely arising as a failure of attention during encoding into or retrieval from visual working memory (WM). Here we present participants with a hybrid WM-AB study while they undergo fMRI to provide insight into the neural underpinnings of this bottleneck. Consistent with a WM-based bottleneck account, fronto-parietal brain areas exhibited a WM load-dependent modulation of neural responses during the AB task. These results are consistent with the view that WM and attention share a capacity-limited resource and provide insight into the neural structures that underlie resource allocation in tasks requiring joint use of WM and attention.This research was supported by a project grant (071944) from the Wellcome Trust to Kimron Shapiro
The cost of serially chaining two cognitive operations
Get PDFAs Turing (1936, Proceedings of the London Mathematical Society) noted, a fundamental process in human cognition is to effect chained sequential operations in which the second operation requires an input from the preceding one. Although a great deal is known about the costs associated with 'independent' (unrelated) operations, e. g., from the classic psychological refractory period paradigm, far less is known about those operations to which Turing referred. We present the results of two behavioural experiments, where participants were required to perform two speeded sequential tasks that were either chained or independent. Both experiments reveal the reaction time cost of chaining, over and above classical dual-task serial costs. Moreover, the chaining operation significantly altered the distribution of reaction times relative to the Independent condition in terms of an increased mean and variance. These results are discussed in terms of the cognitive architecture underlying the serial chaining of cognitive operations. © 2011 Springer-Verlag.Fil: Fan, Zhao. Huazhong Normal University; ChinaFil: Singh, Krish. Cardiff University; Reino UnidoFil: Muthukumaraswamy, Suresh. Cardiff University; Reino UnidoFil: Sigman, Mariano. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física. Laboratorio de Neurociencia Integrativa; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Dehaene, Stanislas. College de France; FranciaFil: Shapiro, Kimron. Bangor University; Reino Unid
Control of visuotemporal attention by inferior parietal and superior temporal cortex
No full textThe human cortical visual system is organized into two major pathways: a dorsal stream projecting to the superior parietal lobe (SPL), considered to be critical for visuospatial perception or on-line control of visually guided movements, and a ventral stream leading to the inferotemporal cortex, mediating object perception 1, 2 and 3. Between these structures lies a large region, consisting of the inferior parietal lobe (IPL) and superior temporal gyrus (STG), the function of which is controversial. Lesions here can lead to spatial neglect 4 and 5, a condition associated with abnormal visuospatial perception 6 and 7 as well as impaired visually guided movements 8 and 9, suggesting that the IPL+STG may have largely a “dorsal” role. Here, we use a nonspatial task [10] to examine the deployment of visuotemporal attention in focal lesion patients, with or without spatial neglect. We show that, regardless of the presence of neglect, damage to the IPL+STG leads to a more prolonged deployment of visuotemporal attention compared to lesions of the SPL. Our findings suggest that the human IPL+STG makes an important contribution to nonspatial perception, and this is consistent with a role that is neither strictly “dorsal” nor “ventral” [11]. We propose instead that the IPL+STG has a top-down control role, contributing to the functions of both dorsal and ventral visual system
Attentional limitations in processing sequentially presented vibrotactile targets
Get PDFIn seven experiments, participants experienced rapid, serially presented streams of vibrations and responded to specific targets in the streams. In visual (and sometimes auditory) streams presented in this manner, it is typical to find a deficit in reporting the second of two targets when both must be reported and the second appears within a short temporal interval of the first, but not when identical displays are presented but only the second target must be reported (e.g., the attentional blink, or AB). This conventional AB pattern was found in the last experiment, in which judgments were about target location. However in the first six experiments reported here, in which judgments were about frequency, intensity, duration, or location of targets, accuracy was dependent on target separation regardless of whether or not the first target was reported. This unconventional pattern could represent an AB if the first target was attended even when it was not reported. The evidence for this claim and an alternative possibility that location judgments are especially sensitive to attention manipulations are discusse
Spatiotemporal dynamics of attention in visual neglect: a case study
No full textPatients with visual neglect are often unaware of contralesional visual stimuli. Recent studies have demonstrated non-spatial as well as spatial deficits in allocating attention in neglect patients. We examined the spatiotemporal dynamics of directing attention in a patient with neglect for visual objects appearing in the left side of space by using a version of the attentional blink paradigm, presenting two visual stimuli in succession. The first target (T1) was presented at fixation. The location of the second target (T2) and time between the two targets was varied. When T2 appeared to the left, the patient required more time between targets to identify both accurately, compared to when T2 appeared at fixation or to the right. Our findings demonstrate a spatial and temporal gradient of attention. The results are discussed with respect to current models of visual processing in visual neglec
Fronto-medial theta coordinates posterior maintenance of working memory content
Get PDFHow does the human brain manage multiple bits of information to guide goal-directed behavior? Successful working memory (WM) functioning has consistently been linked to oscillatory power in the theta frequency band (4–8 Hz) over fronto-medial cortex (fronto-medial theta [FMT]). Specifically, FMT is thought to reflect the mechanism of an executive sub-system that coordinates maintenance of memory contents in posterior regions. However, direct evidence for the role of FMT in controlling specific WM content is lacking. Here, we collected high-density electroencephalography (EEG) data while participants engaged in WM-dependent tasks and then used multivariate decoding methods to examine WM content during the maintenance period. Engagement of WM was accompanied by a focal increase in FMT. Importantly, decoding of WM content was driven by posterior sites, which, in turn, showed increased functional theta coupling with fronto-medial channels. Finally, we observed a significant slowing of FMT frequency with increasing WM load, consistent with the hypothesized broadening of a theta “duty cycle” to accommodate additional WM items. Together, these findings demonstrate that frontal theta orchestrates posterior maintenance of WM content. Moreover, the observed frequency slowing elucidates the function of FMT oscillations by specifically supporting phase-coding accounts of WM
Multisensory Integration: How Sound Alters Sight
No full textSummaryWhat we hear can rapidly alter what we see. A new study provides evidence for a mechanism in which 10 Hz oscillations in the visual system define the time window for integrating auditory and visual information
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