Neural Sources of Focused Attention in Visual Search

Hopf, Jens‐Max; Luck, Steven J.; Girelli, Massimo; Hagner, Tilman; Mangun, George R.; Scheich, Henning; Heinze, Hans Jochen

doi:10.1093/cercor/10.12.1233

Cited by 377 publications

(329 citation statements)

References 35 publications

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“…Whereas the N2pc can shift between locations every 100 ms in a certain type of visual search task (Woodman and Luck, 1999), SSVEPs have been estimated to increase in amplitude only after 600-800 ms relative to the onset of an attention-directing cue (Müller et al, 1998b). Furthermore, the neuronal generators of the components differ: whereas the N2pc has been localized to V4 and the lateral occipital complex (Hopf et al, 2000(Hopf et al, , 2006Praamstra and Oostenveld, 2003), associated with intermediate and higher levels of the visual processing pathway, SSVEPs have been localized to primary visual cortex, V1 (Di Russo et al, 2007), associated with very early visual processing. Ultimately, there is a difference in functional role: whereas the N2pc is thought to reflect the focusing of attention on an item (e.g., Luck, 2012), SSVEPs are thought to reflect a gain-control mechanism that enhances the discriminability of attended stimuli (e.g., Müller et al, 1998b).…”

Section: Discussionmentioning

confidence: 99%

Lateralized electrical brain activity reveals covert attention allocation during speaking

2017

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A B S T R A C TSpeakers usually begin to speak while only part of the utterance has been planned. Earlier work has shown that speech planning processes are reflected in speakers' eye movements as they describe visually presented objects. However, to-be-named objects can be processed to some extent before they have been fixated upon, presumably because attention can be allocated to objects covertly, without moving the eyes. The present study investigated whether EEG could track speakers' covert attention allocation as they produced short utterances to describe pairs of objects (e.g., "dog and chair"). The processing difficulty of each object was varied by presenting it in upright orientation (easy) or in upside down orientation (difficult). Background squares flickered at different frequencies in order to elicit steady-state visual evoked potentials (SSVEPs). The N2pc component, associated with the focusing of attention on an item, was detectable not only prior to speech onset, but also during speaking. The time course of the N2pc showed that attention shifted to each object in the order of mention prior to speech onset. Furthermore, greater processing difficulty increased the time speakers spent attending to each object. This demonstrates that the N2pc can track covert attention allocation in a naming task. In addition, an effect of processing difficulty at around 200-350 ms after stimulus onset revealed early attention allocation to the second to-be-named object. The flickering backgrounds elicited SSVEPs, but SSVEP amplitude was not influenced by processing difficulty. These results help complete the picture of the coordination of visual information uptake and motor output during speaking.

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Section: Discussionmentioning

confidence: 99%

Lateralized electrical brain activity reveals covert attention allocation during speaking

2017

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“…When a candidate target object in the left or right visual field is presented together with distractors, this object triggers an enhanced negativity at contralateral occipito-temporal electrodes (N2pc component; Luck & Hillyard, 1994;Eimer, 1996;Girelli & Luck, 1997). Similar to the target-selective modulations of neural responses described by Chelazzi et al (1998), the N2pc component typically emerges around 180 ms after stimulus onset, and is primarily generated in extrastriate ventral visual cortex (e.g., Hopf et al 2000). It is therefore likely that both measures are linked to the same underlying neural process.…”

Section: Object Selection and Focal Spatial Attentionmentioning

confidence: 99%

EPS Mid-Career Award 2014

Eimer

2015

Quarterly Journal of Experimental Psychology

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In visual search, observers try to find known target objects among distractors in visual scenes where the location of the targets is uncertain. This review article discusses the attentional processes that are active during search and their neural basis. Four successive phases of visual search are described. During the initial preparatory phase, a representation of the current search goal is activated. Once visual input has arrived, information about the presence of target-matching features is accumulated in parallel across the visual field (guidance). This information is then used to allocate spatial attention to particular objects (selection), before representations of selected objects are activated in visual working memory (recognition). These four phases of attentional control in visual search are characterized both at the cognitive level and at the neural implementation level. It will become clear that search is a continuous process that unfolds in real time. Selective attention in visual search is described as the gradual emergence of spatially specific and temporally sustained biases for representations of task-relevant visual objects in cortical maps.3

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“…Electrophysiological evidence based on source localisation with the N2pc component has suggested that shifts of attention initiate in parietal areas; attentional focusing ignites distributed extrastriate areas in the occipital and inferotemporal cortex [131]. Local amplification within modules, in combination with spreading of amplification to other modules amongst neurons coding for the same object, as suggested by the integrated object competition hypothesis, occurs at a relatively early stage.…”

Section: (I) From Visual Features To Proto-objectsmentioning

confidence: 99%

The interplay of attention and consciousness in visual search, attentional blink and working memory consolidation

Raffone

Srinivasan

Leeuwen

2014

Phil. Trans. R. Soc. B

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Despite the acknowledged relationship between consciousness and attention, theories of the two have mostly been developed separately. Moreover, these theories have independently attempted to explain phenomena in which both are likely to interact, such as the attentional blink (AB) and working memory (WM) consolidation. Here, we make an effort to bridge the gap between, on the one hand, a theory of consciousness based on the notion of global workspace (GW) and, on the other, a synthesis of theories of visual attention. We offer a theory of attention and consciousness (TAC) that provides a unified neurocognitive account of several phenomena associated with visual search, AB and WM consolidation. TAC assumes multiple processing stages between early visual representation and conscious access, and extends the dynamics of the global neuronal workspace model to a visual attentional workspace (VAW). The VAWis controlled by executive routers, higher-order representations of executive operations in the GW, without the need for explicit saliency or priority maps. TAC leads to newly proposed mechanisms for illusory conjunctions, AB, inattentional blindness and WM capacity, and suggests neural correlates of phenomenal consciousness. Finally, the theory reconciles the all-or-none and graded perspectives on conscious representation

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Neural Sources of Focused Attention in Visual Search

Cited by 377 publications

References 35 publications

Lateralized electrical brain activity reveals covert attention allocation during speaking

Lateralized electrical brain activity reveals covert attention allocation during speaking

EPS Mid-Career Award 2014

The interplay of attention and consciousness in visual search, attentional blink and working memory consolidation

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